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Voluntary Product Standard PS 1-19
Structural Plywood
December 2019
U.S. Department of Commerce
Wilbur L. Ross, Jr., Secretary
National Institute of Standards and Technology
Walter Copan, NIST Director and Undersecretary of Commerce for
Standards and Technology
Certain commercial entities, equipment, or materials may be identified in this
document in order to describe an experimental procedure or concept adequately.
Such identification is not intended to imply recommendation or endorsement by the
National Institute of Standards and Technology, nor is it intended to imply that the
entities, materials, or equipment are necessarily the best available for the purpose.
Additional information concerning the development and use of this standard can
obtained by contacting the Standards Coordination Office, National Institute of
Standards and Technology, 100 Bureau Drive, MS 2100, Gaithersburg, MD 20899-
2100 or visiting Standards.Gov.
DEPARTMENT OF COMMERCE (DOC) VOLUNTARY PRODUCT STANDARDS
DOC Voluntary Product Standards are developed under procedures published by the Department of
Commerce in Title 15 Code of Federal Regulations Part 10, Procedures for the Development of Voluntary
Product Standards. The purpose of these standards is to establish nationally recognized requirements for
products and to provide all concerned interests with a basis for common understanding of the
characteristics of the products. The National Institute of Standards and Technology (NIST) administers the
Voluntary Product Standards program on a reimbursable basis.
ROLE OF NIST
The role of NIST in the establishment of a DOC Voluntary Product Standard is to act as an unbiased
coordinator in the development of the standard, provide editorial assistance in the preparation of the
standard, supply such assistance and review as is required to assure the technical soundness of the
standard, and seek satisfactory adjustment of valid points of disagreement. NIST also determines
compliance with the criteria of the Department’s procedures and publishes the standard as a public
document.
Producers, distributors, users, consumers, and other interested groups contribute to the establishment of
Voluntary Product Standards. These groups initiate and participate in the development of the standards,
provide technical or other counsel as appropriate, promote the use of and support for the standards, and
assist in keeping them current with respect to advancing technology and marketing practices.
USE OF VOLUNTARY PRODUCT STANDARDS
The use of DOC Voluntary Product Standards is voluntary. NIST has no regulatory power in the
enforcement of their provisions; however, since the standards represent a consensus of interested groups,
their provisions are likely to become established as trade customs.
The benefits derived from a DOC Voluntary Product Standard are in direct proportion to their general
recognition and actual use. Producers and distributors whose products meet the requirements of a DOC
Voluntary Product Standard may refer to the standard in advertising and on labels to promote greater public
understanding for confidence in their products. At times, purchasers may order products conforming to the
requirements of a DOC Voluntary Product Standard.
Abstract
These standard covers performance requirements, adhesive bond performance, grades, panel construction
and workmanship, dimensions and tolerances, marking, and moisture content of structural plywood. The
standard classifies structural plywood by bond classification, span rating, performance category, and grade.
It provides test methods, a glossary of trade terms and definitions, and a quality certification program
whereby agencies inspect, sample, and test products for conformance to this standard. Information
regarding industry practices for reinspection, history of the standard, labeling, and formaldehyde attributes
are provided in nonmandatory appendices.
Keywords
Adhesive bond classification; certification; construction sheathing; dimensions and tolerances; marking;
moisture content; performance requirements; span rating; performance category; structural plywood; test
methods; voluntary standard.
i
Table of Contents

1. SCOPE…………………………………………………………………………………………………………………… 1
2. TERMINOLOGY………………………………………………………………………………………………………. 1
   3 REFERENCE PUBLICATIONS ………………………………………………………………………………… 8
3. PLYWOOD CLASSIFICATION………………………………………………………………………………….. 9
   4.1 General …………………………………………………………………………………………………………… 9
   4.2 Bond classification ……………………………………………………………………………………………. 9
   4.3 Grade……………………………………………………………………………………………………………… 9
4. REQUIREMENTS…………………………………………………………………………………………………….. 9
   5.1 General …………………………………………………………………………………………………………… 9
   5.2 Wood species ………………………………………………………………………………………………….. 9
   5.3 Synthetic repairs …………………………………………………………………………………………….. 11
   5.4 Grade desription of veneers …………………………………………………………………………….. 11
   5.5 Veneers and layers…………………………………………………………………………………………. 17
   5.6 Panel grades………………………………………………………………………………………………….. 18
   5.7 Adhesive bond requirements for a panel or a lot…………………………………………………. 22
   5.8 Panel constructions and workmanship ………………………………………………………………. 24
   5.9 Scarf and finger jointed panels …………………………………………………………………………. 36
   5.10 Dimensional tolerances and squareness of panels……………………………………………… 39
   5.11 Moisture content …………………………………………………………………………………………….. 39
   5.12 Loading or packing …………………………………………………………………………………………. 39
5. SPECIMEN PREPARATION AND TESTING…………………………………………………………….. 39
   6.1 Bond classification ………………………………………………………………………………………….. 39
   6.2 Structural performance ……………………………………………………………………………………. 44
   7 GRADEMARKING AND CERTIFICATION………………………………………………………………… 48
   7.1 Certification……………………………………………………………………………………………………. 48
   7.2 Qualified inspection and testing agency …………………………………………………………….. 48
   7.3 Panel marking………………………………………………………………………………………………… 49
   7.4 Voiding marks ………………………………………………………………………………………………… 49
   8 EFFECTIVE DATE…………………………………………………………………………………………………. 50
   9 STANDING COMMITTEE……………………………………………………………………………………….. 50
   ii
   APPENDIX
   A Species Grouping (mandatory) ……………………………………………………………………………….. 51
   B Reinspection Practices (nonmandatory) …………………………………………………………………… 54
   C General Information and Comments on Current Edition (nonmandatory) ……………………… 56
   D Recommend thickness labels (nonmandatory)………………………………………………………….. 58
   E Labeling Guidelines Based on the Uniform Packaging and Labeling Regulations of NIST
   Handbook 130 and Handbook 133 (nonmandatory)…………………………………………………… 60
   F Formaldehyde (nonmandatory)……………………………………………………………………………….. 61
   1
   VOLUNTARY PRODUCT STANDARD PS 1-19
   STRUCTURAL PLYWOOD
   Effective December 1, 2019
   (This Standard, which was initiated by APA – The Engineered Wood Association [formerly the
   American Plywood Association], has been developed under the Procedures for the
   Development of Voluntary Product Standards of the U.S. Department of Commerce as a
   revision of PS 1-09, Structural Plywood.)
6. SCOPE
   1.1 This Voluntary Product Standard establishes requirements for the principal types and
   grades of structural plywood and provides a basis for common understanding among producers,
   distributors, and users of the product.
   1.2 This Standard covers the wood species, veneer grading, adhesive bonds, panel
   construction and workmanship, dimensions and tolerances, marking, moisture content, and
   packaging of structural plywood intended for construction and industrial uses.
   1.3 Included in this Standard are test methods to determine compliance and a glossary of trade
   terms and definitions. A quality certification program is provided whereby qualified testing
   agencies inspect, sample, and test products identified as complying with this Standard.
   Information on species grouping is provided in Appendix A. Information on reinspecting
   practices is provided in Appendix B. Information on the maintenance, history, and current
   edition of the Standard is provided in Appendix C. Recommended thickness labeling is provided
   in Appendix D. Information on labeling regulations from NIST Handbook 130 and NIST
   Handbook 133 are provided in Appendix E. Information on formaldehyde emissions is provided
   in Appendix F.
   1.4 This Voluntary Product Standard incorporates the International System of Units (SI) as well
   as U.S. customary units of measurement. In conversion of U.S. customary units where exact
   placement is not an issue, such as nail spacing, approximate conversions to SI units are made
   to yield more easily recognizable numbers. In critical matters, such as panel thickness, more
   precise conversions to SI units are made. For nominal U.S. customary units, actual dimensions
   in SI units are given. The values given in SI units are the standard. The values in parentheses
   are for information only.
   1.5 Advisory notes in this Standard and Appendices B through F are informational and shall not
   be considered mandatory.
7. TERMINOLOGY
   2.1 Back
   Back of a plywood panel — The side of a panel that is of lower veneer quality on any panel
   whose outer plies (front and back) are of different veneer grades.
   Back ply of a plywood panel — The outer veneer on the back side of a panel.
   2
   2.2 Bond classifications
   Plywood is rated as Exposure 1 or Exterior bond classification. (See Sections 2.20 and 2.21.)
   2.3 Borer holes
   Voids made by wood-boring insects, such as grubs or worms.
   2.4 Broken grain
   A separation on veneer surface between annual rings, such as leafing or shelling.
   2.5 Butt joint
   A straight joint in which the interface is perpendicular to the panel face. An end butt joint is
   perpendicular to the grain.
   2.6 Centers
   Inner layers whose grain direction runs parallel to that of the outer plies. Some centers consist
   of parallel laminated plies.
   2.7 Center gap
   See Section 2.16.
   2.8 Characteristics, growth
   Discolorations, pitch streaks and knots that naturally occur in wood.
   2.9 Characteristics, open
   Irregularities such as splits, open joints, knotholes, loose knots, or wane.
   2.10 Check
   A lengthwise separation of wood fibers, usually extending across the rings of annual growth,
   caused chiefly by strains produced in seasoning.
   2.11 Class I, II
   Term used to identify different classifications of concrete form panels. (See Section 5.6.4.)
   2.12 Construction (panel construction)
   Term referring to detailed manner in which veneers are assembled and/or thickness of veneer
   used, e.g., “4-ply 3-layer construction,” “2.5 mm (1/10 in) face and back,” etc.
   2.13 Core
   See Section 2.15.
   2.14 Critical Section
   A rectangular area measuring 305 mm (12 in) along the grain by full panel width that contains a
   knot or knothole requiring additional consideration. (See Sections 5.4.4.3, 5.4.6.2 and 5.4.6.3)
   2.15 Crossband
   Inner, or core, plies whose grain direction runs perpendicular to that of the outer plies. Some
   crossbands consist of parallel laminated plies.
   2.16 Crossband gap and center gap
   An open joint extending through or partially through a panel, which results when crossband or
   center veneers are not tightly butted.
   3
   2.17 Delamination
   A visible separation between plies that normally receive adhesive at their interface and are
   firmly contacted in the pressing operation. Wood characteristics such as checking, leafing,
   splitting and broken grain are not to be construed as delamination.
   2.17.1 Knotholes, pitch pockets, splits and gaps
   For purpose of evaluation of delamination, areas coinciding with open knotholes, pitch pockets,
   splits, gaps, and other voids or characteristics permitted in the panel grade are not considered
   in evaluating ply separation.
   2.17.2 Delamination of Exposure 1 Panels
   In evaluating Exposure 1 panels, delamination in any bond line is not to exceed 19.4 cm2 (3 in2
   )
   except where directly attributable to characteristics permitted in the grade as follows:
   Delamination associated with:
   (a) Knots and knotholes — Not to exceed the size of the knot or knothole plus a
   surrounding band not wider than 19.1 mm (3/4 in).
   (b) All other forms of permissible characteristics — Not to exceed the size of the
   characteristic.
   2.17.3 Delamination of Exterior Panels
   For purposes of evaluation of Exterior panels for ply separation, the area coinciding with the
   grade characteristics noted in Section 2.17.1 is considered, and a panel is considered
   delaminated if visible ply separation at a single bond line in such area exceeds 19.4 cm2 (3 in2
   ).
   2.18 Depression
   A minor disruption of the panel surface with a smooth boundary.
   2.19 Edge splits
   Wedge-shaped openings in the inner plies caused by splitting of the veneer before pressing.
   2.20 Exposure 1
   Bond classification for panels suitable for uses not permanently exposed to the weather. Panels
   classified as Exposure 1 are intended to resist the effects of moisture on structural performance
   as may occur during construction, or other conditions of similar severity.
   2.21 Exterior
   Bond classification for panels suitable for repeated wetting and redrying or long-term exposure
   to weather or other conditions of similar severity.
   2.22 Face
   Face of the plywood panel — The side of a panel that is of higher veneer quality on any panel
   whose outer plies (front and back) are of different veneer grades; either side of a panel where
   the grading rules draw no distinction between outer plies.
   Face ply of a panel — The outer veneer on the face of a panel.
   4
   2.23 Finger joint
   Term indicating the method by which panels or sections of panels have been joined to create
   longer lengths or widths by means of a well-bonded series of sloped scarf cuts resembling
   fingers.
   2.24 Group
   Term used to classify species or panels covered by this Standard. Species covered by this
   Standard are classified as Groups 1, 2, 3, 4, and 5. See Table 1 and Appendix A for listing of
   species in individual groups. Section 5.8.7 provides procedures for grouping of panels with
   species not listed in Table 1.
   2.25 Heartwood
   Nonactive core of a log generally distinguishable from the outer portion (sapwood) by its darker
   color.
   2.26 Indent
   A disruption of the panel surface with sharp or distinct edges.
   2.27 Inner plies
   Plies other than face or back plies in a panel construction. Sub-face, sub-back, crossband and
   center are classed as inner plies.
   2.28 Jointed inner plies
   Crossband and center veneers with edges machine-squared to permit tightest possible layup.
   2.29 Knot
   Natural characteristic of wood that occurs where a branch base is embedded in the trunk of a
   tree. Generally the size of a knot is distinguishable by (1) a difference in color of limb wood and
   surrounding trunk wood; (2) an abrupt change in growth ring width between knot and bordering
   trunk wood; and (3) a diameter of circular or oval shape described by points where checks on
   the face of a knot that extend radially from its center to its side experience an abrupt change in
   direction.
   2.30 Knotholes
   Voids produced by the dropping of knots from the wood in which they were originally embedded.
   2.31 Lap
   A condition where the veneers in the same ply are so placed that one piece overlaps the other.
   2.32 Layer
   A single veneer ply or two or more plies laminated with grain direction parallel. Two or more
   plies laminated with grain direction parallel is a “parallel laminated layer.”
   2.33 Lot
   Any number of panels considered as a single group for evaluating conformance to this
   Standard.
   2.34 Major panel axis
   The direction parallel to the grain of the face and back plies.
   5
   2.35 Mill specification
   A manufacturing specification based on product evaluation to be used for quality assurance
   purposes by the manufacturer and the qualified testing agency as defined in Section 7.2. (See
   Sections 5.8.6.5. and 5.8.7.3.)
   2.36 Moisture content
   The weight of the water in wood expressed as a percent of the weight of the oven-dry wood.
   (See Section 6.1.4.)
   2.37 Moisture resistant adhesive
   Adhesive capable of bonding plywood in a manner to satisfy the bond classification
   requirements of this Standard.
   2.38 Panel thickness
   Designated thickness subject to tolerances specified in this Standard. See Section 5.10.2 for
   thickness tolerances. See Section 2.40 for definition of Performance Category.
   2.39 Patches
   Inserts of sound wood or synthetic material in veneers or panels for replacing characteristics
   (open or growth). “Boat” patches are oval-shaped with sides tapering in each direction to a
   point or to a small rounded end. “Compound Boat” patches have multiple rounded or pointed
   ends. “Router” patches have parallel sides and rounded ends. “Sled” patches are rectangular
   with feathered ends.
   2.40 Performance Category
   A panel designation related to the panel thickness range that is linked to the nominal panel
   thickness designations used in the International Building Code (IBC) and International
   Residential Code (IRC). For purposes of labeling, as defined in Section 7.3, abbreviations PERF
   CAT, CAT or Category are permitted.
   ADVISORY NOTE: The IRC and IBC specify a minimum 3/8 Performance Category for wall
   sheathing.
   2.41 Performance testing
   Tests that evaluate panel attributes typically required in the end-use applications as defined in
   this Standard.
   2.42 Pitch pocket
   A well-defined opening between rings of annual growth, usually containing, or which has
   contained, pitch, either solid or liquid.
   2.43 Pitch streak
   A localized accumulation of resin in coniferous woods which permeates the cells forming resin
   soaks, patches, or streaks.
   2.44 Plugs
   Sound wood of various shapes, including among others, circular and dog-bone, for replacing
   portions of veneers. Also, synthetic plugs used to fill openings and provide a smooth, level,
   durable surface. Plugs usually are held in veneer by friction until veneers are bonded into
   plywood.
   6
   2.45 Plugged inner plies (also referred to as solid inner plies.)
   Refers to C Plugged crossband and centers and additional limitations, as given in Section 5.8.1.
   2.46 Ply
   A single veneer lamina in a bonded plywood panel. (See also 2.32.)
   2.47 Plywood
   Plywood is a panel built up of sheets of veneer called plies, united under pressure by a bonding
   agent to create a panel with an adhesive bond between plies as strong as or stronger than, the
   wood. Plywood is constructed of an odd number of layers with grain of adjacent layers
   perpendicular. Layers consist of a single ply or two or more plies laminated with parallel grain
   direction. Outer layers and all odd-numbered layers generally have the grain direction oriented
   parallel to the long dimension of the panel. The layers with alternating grain direction equalize
   strains, reduce splitting, and minimize dimensional change and warping of the panel.
   2.48 Plywood classification
   Plywood is classified by bond classification and grade. (See Section 4.)
   2.49 Prescriptive specification
   A specification based upon manufacturing parameters that define the approved product.
   2.50 Reference value
   The numerical value established for the mill specification for a given mechanical or physical
   property.
   2.51 Repair
   Any patch plug or shim.
   2.52 Rough grain
   Grain characteristics which prevent sanding to a smooth surface.
   2.53 Sapwood
   The living wood of lighter color occurring in the outer portion of a log. Sometimes referred to as
   “sap.”
   2.54 Scarfed joint
   A term indicating the method by which panels or veneer, or sections of panels or veneer, have
   been joined to create longer lengths or widths by means of a well-bonded, sloped cut.
   2.55 Shim
   A long, narrow repair of wood or suitable synthetic not more than 4.8 mm (3/16 in) wide.
   2.56 Shop-cutting panel
   Panel which has been rejected as not conforming to a standard grade because of deficiencies,
   other than adhesive bond quality, which prevent it from meeting the requirements of this
   Standard. Blistered panels are not permitted within the category of “shop-cutting panel.”
   Localized delamination occurring as a result of a deficiency is permitted. Shop-cutting panels
   are suitable for cut-up use where cutting eliminates the deficiency in the portion of the panel
   salvaged. The salvageable area shall be at least 85% of the area of the panel. Such a panel
   must be identified with a separate mark as specified in Section 7.4.
   7
   2.57 Sized for Spacing
   An optional panel mark indicating that the panel manufacturer has sized the panel to allow for
   industry recommended panel installation spacing.
   2.58 Span rating
   An index number, based on customary inch units, that identifies the recommended maximum
   center-to-center support spacing, or “on-center” (o.c.) spacing, for the specified end use under
   normal use conditions. Spans are defined for end uses such as roof, subfloor, and single floor.
   As a matter of convention, spans are typically specified by a single index number for single floor
   (Floor 24 o.c.), while roof and subfloor are often combined in a fractional format. For example, a
   span rating of 32/16 designates a roof span of 32 inches and a subfloor span of 16 inches. As a
   matter of convention, a span rating of 20 is designated for spans of 19.2 inch.
   2.59 Split
   Lengthwise separation of wood fibers completely through the veneer, caused chiefly by the
   manufacturing process or handling.
   2.60 Sub-face (sub-back)
   The ply adjacent to the exposed face (or back) of a parallel laminated outer layer.
   2.61 Touch-sanding
   A sizing operation consisting of a light surface sanding to thickness dimension in a sander.
   Sander skips to any degree are admissible.
   2.62 Veneer
   Thin sheets of wood of which plywood is made. Also referred to as “plies” in the bonded panel.
   2.63 Wane
   Thin to open areas in veneer sheets that result from outer log surface irregularities. Some wane
   areas contain bark inclusions. For grading, wane is classed as an open characteristic.
   2.64 White pocket
   A form of fungal decay (Fomes pini) that attacks most conifers but has never been known to
   develop in wood in service. In plywood manufacture, routine drying of veneer effectively
   removes any possibility of the fungus surviving. Also known as white speck.
   2.64.1 Light white pocket
   Advanced beyond incipient or stain stage to a point where pockets are present and plainly
   visible, mostly small and filled with white cellulose; generally distributed with no heavy
   concentrations; pockets for the most part separate and distinct; few to no holes through the
   veneer.
   2.64.2 Heavy white pocket
   Contains a great number of pockets, in dense concentrations, running together and at times
   appearing continuous; holes extend through the veneer but wood between pockets appears
   firm. At any cross section extending across the width of the affected area, sufficient wood fiber
   shall be present to develop not less than 40% of the strength of clear veneer. Brown cubicle
   and similar forms of decay which have caused the wood to crumble are prohibited.
   8
   2.65 Wood failure (percent)
   The area of wood fiber remaining at the bond line following completion of the specified shear
   test. Determination is by means of visual examination and expressed as a percent of the test
   area.
   2.66 Working Face
   A face and/or back of a plywood panel that has an overlay system that meets a defined MDO or
   HDO grade (see section 5.6.7).
8. REFERENCE PUBLICATIONS 1
   ASTM E661-03 (2015) Test Method for Performance of Wood and Wood-Based Floor and Roof
   Sheathing Under Concentrated Static and Impact Loads.
   ASTM D2555-17 Test Methods for Establishing Clear Wood Strength Values.
   ASTM D2718-18 Test Method for Structural Panels in Planar Shear (Rolling Shear).
   ASTM D2719-13 Test Methods for Structural Panels in Shear Through-the-Thickness.
   ASTM D2915-17 Standard Practice for Evaluating Allowable Properties for Grades of Structural
   Lumber.
   ASTM D3043-17 Methods of Testing Structural Panels in Flexure.
   ASTM D5266-13 Standard Practice for Estimating the Percentage of Wood Failure in Adhesive
   Bonded Joints.
   ASTM D906-98 (2017) Standard Test Method for Strength Properties of Adhesives in Plywood
   Type Construction in Shear by Tension Loading.
   International Building Code® (IBC). International Code Council. Country Club Hills, IL.
   International Residential Code® for One- and Two-Family Dwellings (IRC). International Code
   Council. Country Club Hills, IL.
   PS 2-18 Performance Standard for Wood Structural Panels.
   ISO/IEC 17020 Conformity Assessment – Requirements for the Operation of Various Types of
   Bodies Performing Inspection.
   ISO/IEC 17025 General Requirements for the Competence of Testing and Calibration
   Laboratories.
   ISO/IEC 17065 Conformity Assessment – Requirements for bodies certifying products,
   processes and services.
   1 Copies of the ASTM publications are available from ASTM International, 100 Barr Harbor Drive, PO Box
   C700, West Conshohocken, PA 19428-2959, www.astm.org.
   9
9. PLYWOOD CLASSIFICATION
   4.1 General
   The plywood covered by this Standard is classified by bond classification and by grade.
   4.2 Bond classification
   The plywood covered by this Standard is classified as either Exposure 1 or Exterior. Each
   classification is a function of veneer grade and adhesive performance. The bond classification is
   related to the moisture resistance of the adhesive bond under intended end-use conditions and
   does not relate to the physical (erosion, ultraviolet, etc.) or biological (mold, fungal decay,
   insect, etc.) resistance of the panel.
   4.2.1 Exposure 1 plywood
   Adhesive performance requirements for Exposure 1 plywood are provided in Section 5.7.1.
   4.2.2 Exterior plywood
   Adhesive performance requirements for Exterior plywood are provided in Section 5.7.2.
   4.3 Grade
   Within each bond classification, there are a number of panel grades based on the grade of the
   veneers and the panel construction. (See Table 2 for Exposure 1 grades and Table 3 for
   Exterior grades.)
10. REQUIREMENTS
    5.1 General
    All plywood panels represented as conforming to this Standard shall meet or exceed all
    applicable requirements set forth herein. Test methods are given in Section 6. All terms shall
    be as defined in Section 2. Requirements for trademarking and certification shall be as
    provided in Section 7.
    5.2 Wood species
    5.2.1 Species groups
    For the purpose of this Standard, species shall be any softwood or hardwood species or trade
    groups listed in Table 1 and other species meeting the requirements of Sections 5.2.3 or 5.2.4.
    For species grouping purposes, species listed in Table 1 but grown in a different geographic
    region shall be evaluated in accordance with Appendix A. For inclusion in Table 1, unlisted
    species shall be evaluated in accordance with Appendix A.
    5.2.1.1 Species segregation
    Species which cannot be distinguished in veneer form from similar species shall be classed as
    the largest numbered species group applicable (Group 4 is larger numbered than Group 1)
    unless the manufacturer provides valid evidence to the qualified inspection and testing agency
    that the species are properly segregated. Such segregation shall be in the form of separation
    prior to peeling, mechanical testing for performance capability, or other means approved by the
    qualified inspection and testing agency.
    5.2.2 Species for faces and backs
    Unless evaluated in accordance with Section 5.2.4, the species of face and back plies shall be
    from any group listed in Table 1. When a face or back is made of more than one piece, the
    entire ply shall be of the same species. When outer layers consist of two or more plies, the
    10
    outer or exposed plies are classified as faces (face plies) or backs (back plies) and the
    unexposed plies (sub-faces and sub-backs) are classified as inner plies, in terms of species
    requirements as provided in Section 5.2.3. Requirements for identification of all panels are
    given in Section 7.3.
    TABLE 1. CLASSIFICATION OF SPECIES(a)
    Group 1 Group 2 Group 3 Group 4 Group 5
    North American Species – Applicable to trees grown in North America
    Beech, American Cedar, Port Orford Pine Alder, Red Aspen Basswood
    Birch Cypress Pond Birch, Paper Bigtooth Poplar, Balsam
    Sweet Douglas-fir (b) Red Cedar, Alaska Quaking
    Yellow Fir Virginia Fir, Subalpine Cedar
    Douglas-fir (b) Balsam Western White Hemlock, Eastern Incense
    Larch, Western California Red Spruce Maple, Bigleaf Western Red
    Maple, Sugar Grand Black Pine Cottonwood
    Pine, Southern Noble Red Jack Eastern
    Loblolly Pacific Silver Sitka Lodgepole Black (W. Poplar)
    Longleaf White Sweetgum Ponderosa Pine
    Shortleaf Hemlock, Western Tamarack Spruce Eastern White
    Slash Maple, Black Yellow Poplar Redwood Sugar
    Tanoak Spruce
    Engelmann
    White
    Non North American Species
    Apitong(c)(d) Lauan Mengkulang(c) Cativo
    Kapur(c) Almon Meranti, Red(c)(e)
    Keruing(c)(d) Bagtikan Mersawa(c)
    Pine Mayapis
    Caribbean Red Lauan
    Ocote Tangile
    White Lauan
    (a) Table 1 species classified in accordance with ASTM D 2555 as discussed in Appendix A. The species groupings are only
    valid for species grown in the regions referenced in Appendix A. (See Section 5.2.1.)
    (b) Douglas-fir from trees grown in the states of Washington, Oregon, California, Idaho, Montana, Wyoming, and the
    Canadian Provinces of Alberta and British Columbia shall be classed as Group 1 Douglas-fir. Douglas-fir from trees
    grown in the states of Nevada, Utah, Colorado, Arizona and New Mexico shall be classed as Group 2 Douglas-fir. (c) Each of these names represents a trade group of woods consisting of a number of closely related species.
    (d) Species from the genus Dipterocarpus marketed collectively: Apitong if originating in the Philippines, Keruing if
    originating in Malaysia or Indonesia.
    (e) Red Meranti shall be limited to species having a specific gravity of 0.41 or more based on green volume and oven dry
    weight.
    5.2.3 Species for inner plies
    5.2.3.1 Inner ply species group
    Unless otherwise permitted in Section 5.2.3.2 or 5.2.4, inner plies of Groups 1, 2, 3 or 4 panels
    shall be of any species listed in Groups 1, 2, 3 or 4 in Table 1. Inner plies of Group 5 panels are
    permitted to be any species listed in Table 1.
    5.2.3.2 Inner ply specific gravity
    Inner plies of all panels shall also be permitted to be of any softwood species or any hardwood
    species having a published average specific gravity value of 0.41 or more based on green
    volume and oven dry weight. The U.S. Forest Products Laboratory shall be considered as final
    evaluator of published specific gravity data.
    11
    5.2.4 Species classified by testing
    Species not listed in Table 1 or otherwise not covered by the provisions of Section 5.2 shall be
    qualified for use by panel performance testing in accordance with Section 5.8.6 for span-rated
    panels or with Section 5.8.7 for other panels except concrete form, Marine and Structural I
    grades. For panel marking purposes, re-classification of Group designation for species listed in
    Table 1 by panel performance testing in accordance with Section 5.8.7 is permitted.
    5.3 Synthetic repairs
    5.3.1 Synthetic fillers
    Use of synthetic fillers shall be limited to the repair of minor characteristics as specified.
    Synthetic fillers shall be approved by the qualified testing and inspection agency.
    5.3.2 Synthetic shims, patches, and plugs
    These repairs shall completely fill kerfs or voids; shall present a smooth, level surface; and shall
    not crack, shrink, or lose their bond. Performance of synthetic shims, patches, and plugs under
    normal conditions of service shall be comparable to that of wood repairs. The equivalency shall
    be established by the qualified testing and inspection agency.
    5.4 Grade description of veneers
    All veneers in the finished plywood panel shall conform to one of the grade requirements listed
    in Sections 5.4.1 through 5.4.6. Unless otherwise stated, these requirements apply to 1220 mm
    by 2440 mm (48 x 96 in) panels and are proportionate for other sizes. Grade N is the highest
    classification. For grading purposes, depressions (see Section 2.18) shall be considered as
    rough grain.
    5.4.1 Grade N veneer (intended for natural finish)
    5.4.1.1 General
    Grade N veneer shall be smoothly cut 100% heartwood or 100% sapwood, free from knots,
    knotholes, pitch pockets, open splits, other open characteristics, and stain. The veneer shall
    consist of not more than two pieces in 1220 mm (48 in) widths and not more than three pieces
    in wider panels, and shall be well matched for color and grain. When sanding is required (see
    Tables 2 and 3) panels shall be sanded and shall permit no sander skips.
    Synthetic fillers shall be permitted to fill:
    (a) Small cracks or checks not more than 0.8 mm (1/32 in) wide.
    (b) Small splits or openings up to 1.6 mm (1/16 in) wide if not exceeding 50.8 mm
    (2 in) in length.
    (c) Small chipped areas or openings not more than 3.2 mm wide by 6.4 mm long
    (1/8 inch x 1/4 inch).
    5.4.1.2 Growth characteristics
    Where pitch streaks occur, each shall average not more than 9.5 mm (3/8 in) in width and shall
    blend with the color of the wood.
    5.4.1.3 Repairs
    Repairs shall be of wood, neatly made, and parallel to grain. They shall be limited to a total of
    six in number and be well matched for color and grain.
    12
    Patches shall be limited to three “router” patches not exceeding 25.4 mm (1 in) in width and
    88.9 mm (3-1/2 in) in length. There shall be no overlapping.
    Shims shall not exceed 4.8 mm (3/16 in) in width or 305 mm (12 in) in length and shall occur
    only at the ends of the panel.
    5.4.2 Grade A veneer (suitable for painting)
    5.4.2.1 General
    Grade A veneer shall be firm, smoothly cut, and free of knots, pitch pockets, open splits, and
    other open characteristics and well joined when of more than one piece. When sanding is
    required (see Tables 2 and 3) panels shall be sanded and shall permit no sander skips.
    Synthetic fillers shall only be used to fill:
    (a) In Exterior panels: small cracks or checks not more than 0.8 mm (1/32 in) wide;
    small splits or openings up to 1.6 mm (1/16 in) wide, if not exceeding 50.8 mm
    (2 in) in length; small chipped areas or openings not more than 3.2 mm (1/8 in)
    wide by 6.4 mm (1/4 in) long.
    (b) In Exposure 1 panels: small cracks or checks not more than 4.8 mm (3/16 in)
    wide; openings or depressions up to 12.7 mm (1/2 in) wide by 50.8 mm (2 in)
    long or equivalent area.
    5.4.2.2 Growth characteristics
    Where pitch streaks occur, each shall average not more than 9.5 mm (3/8 in) in width and shall
    blend with the color of the wood. Sapwood and discolorations to any degree shall be permitted.
    5.4.2.3 Repairs
    Repairs shall be of wood or synthetic patching material, neatly made, parallel to grain and
    limited to a total of 18 in number, excluding shims.
    5.4.2.4 Patches
    Patches, when of wood, shall be “boat,” “compound boat,” “router,” or “sled” type. The radius of
    ends of boat patches and compound boat patches shall not exceed 9.5 mm (3/8 in).
    A single wood patch shall be no larger than 57.2 mm x 114 mm (2-1/4 in x 4-1/2 in).
    Multiple wood repairs shall consist of not more than two patches, neither of which shall exceed
    178 mm (7 in) in length if either is wider than 25.4 mm (1 in), except that one multiple repair
    consisting of three die-cut veneer patches shall be permitted.
    For a multiple repair consisting of three patches across the width of the panel, the repaired area
    shall not exceed a width and length of 152 mm x 114 mm (6 in x 4-1/2 in)
    For a multiple repair consisting of three patches along the length of the panel, the repaired area
    shall not exceed a width and length of 57.2 mm x 267 mm (2-1/4 in x 10-1/2 in)
    Synthetic repairs are limited to the same repair areas as wood patches and shall be counted as
    one, two or three patches depending on the area repaired.
    13
    The repair of a split having a width not greater than 31.8 mm (1-1/4 in) and any length shall be
    considered one patch.
    Shims shall not be used over or around patches or as multiple repairs.
    5.4.3 Grade B veneer
    5.4.3.1 General
    Grade B veneer shall be solid and free from open characteristics and broken grain, except as
    permitted in Sections 5.4.3.1 through 5.4.3.4. Slightly rough grain shall be permitted.
    Minor sanding and patching characteristics, including sander skips, shall not exceed 5% of
    panel area. See Tables 2 and 3 for sanding requirements.
    Synthetic fillers shall only be used to fill:
    (a) In Exterior panels: small splits or openings up to 1.6 mm (1/16 in) wide if not
    exceeding 50.8 mm (2 in) in length; small chipped areas or openings not more
    than 3.2 mm wide by 6.4 mm long (1/8 in x 1/4 in).
    (b) In Exposure 1 panels: small cracks or checks not more than 4.8 mm (3/16 in)
    wide; openings or depressions up to 12.7 mm wide by 50.8 mm long (1/2 in x
    2 in) or equivalent area.
    5.4.3.2 Growth characteristics
    Knots shall not exceed 25.4 mm (1 in) measured across the grain and shall be both sound and
    tight.
    Where pitch streaks occur, they shall average not more than 25.4 mm (1 in) in width.
    Discolorations to any degree shall be permitted.
    5.4.3.3 Open characteristics
    Splits shall not be wider than 0.8 mm (1/32 in).
    Vertical borer holes shall not exceed 1.6 mm (1/16 in) in diameter and shall not exceed an
    average of one per 929 cm2 (1 ft2
    ) in number.
    Horizontal or surface worm and borer holes shall be limited to 1.6 mm (1/16 in) across,
    25.4 mm (1 in) in length, and limited to 12 in number.
    5.4.3.4 Repairs
    Repairs shall be of wood or synthetic patching material and neatly made.
    Wood veneer repairs shall be die cut. Wood panel repairs shall be “router” or “sled” type.
    Wood repairs shall not exceed 76.2 mm (3 in) in width where occurring in multiple repairs, or
    102 mm (4 in) in width where occurring singly.
    Synthetic veneer repairs shall not exceed 102 mm (4 in) in width.
    14
    Synthetic panel repairs shall not exceed 57.2 mm (2-1/4 in) in width by any length, except that
    repaired areas not exceeding 152 mm in width by 114 mm in length (6 in x 4-1/2 in) shall be
    allowed.
    Shims shall be permitted without limit.
    5.4.4 Grade C veneer
    5.4.4.1 General
    Sanding characteristics shall not impair the strength or serviceability of the panel. See Tables 2
    and 3 for sanding requirements.
    5.4.4.2 Growth characteristics
    Knots shall be tight and not more than 38.1 mm (1-1/2 in) across the grain.
    Discolorations to any degree shall be permitted.
    5.4.4.3 Open characteristics
    Any number of knotholes up to 25.4 mm (1 in) shall be permitted. However, an occasional
    knothole more than 25.4 mm (1 in) but not more than 38.1 mm (1-1/2 in) measured across the
    grain shall be permitted subject to the following provision:
    (a) Determine the Critical Section containing the knothole. (See Section 2.14.)
    (b) Determine the aggregate width of all knots and knotholes occurring wholly within
    the Critical Section. Other open characteristics and growth characteristics are
    not included in this aggregate.
    (c) The knothole is permitted if the aggregate width of all knots and knotholes in the
    Critical Section does not exceed 152 mm (6 in) in a 1220 mm (48 in) wide panel
    and proportionately for other panel widths.
    Splits measured at a point 203 mm (8 in) from the end of the panel shall not exceed 12.7 mm
    (1/2 in) in width by 1/2 panel length or 9.5 mm (3/8 in) in width by any panel length, provided
    separation at one end does not exceed 1.6 mm (1/16 in) where split runs full panel length;
    however, the maximum width within 203 mm (8 in) of the end of the panel (open end of split)
    shall not exceed the maximum width of knotholes permitted within the grade.
    Splits on panel faces and backs shall not exceed 6.4 mm (1/4 in) where located within
    25.4 mm (1 in) of parallel panel edge.
    Voids due to missing wood on panel faces and backs not otherwise specified above shall not
    exceed the maximum width of knotholes permitted in the grade and the length of such voids
    shall not exceed 152 mm (6 in).
    Wane not exceeding 203 mm (8 in) in length and the width permitted for open characteristics
    shall be allowed, providing that where wane occurs at edges of veneer sheets, panel ply
    separation due to wane shall not exceed the limit equivalent to that permitted for short and
    narrow inner plies in Section 5.8.3 for sanded panels, or Section 5.8.4 for unsanded or touchsanded panels.
    15
    5.4.4.4 Repairs
    Repairs shall be wood or synthetic patching material, neatly made.
    Wood veneer repairs shall be die cut. Wood panel repairs shall be “router” or “sled” type.
    Wood repairs shall not exceed 76.2 mm (3 in) in width where occurring in multiple repairs, or
    102 mm (4 in) in width where occurring singly.
    Synthetic veneer repairs shall not exceed 102 mm (4 in) in width.
    Synthetic panel repairs shall not exceed 57.2 mm (2-1/4 in) in width.
    Shims shall be permitted without limit.
    5.4.5 Grade C plugged veneer
    Knotholes, worm and borer holes, and other open characteristics not larger than 6.4 mm (1/4 in)
    by 12.7 mm (1/2 in); sound and tight knots up to 38.1 mm (1-1/2 in) measured across the grain;
    splits up to 3.2 mm (1/8 in) wide; broken grain; pitch pockets, if solid and tight; plugs; patches
    and shims shall be permitted. Synthetic repairs in veneer shall not exceed 102 mm (4 in) in
    width. Synthetic panel repairs shall not exceed 57.2 mm (2-1/4 in) in width by any length,
    except that repaired areas not exceeding 152 mm (6 in) in width by 114 mm (4-1/2 in) in length
    shall be allowed. See Tables 2 and 3 for sanding requirements. Where grades having C
    Plugged face veneer are identified as fully sanded, sanding characteristics shall be the same as
    admitted under B grade. Sander skips to any degree shall be admissible in touch-sanded C
    Plugged veneer.
    5.4.6 Grade D veneer
    5.4.6.1 General
    Except as otherwise required in Sections 5.4.6.2 through 5.4.6.4, any number of plugs, patches,
    shims, worm or borer holes, sanding characteristics, and other characteristics shall be
    permitted, provided they do not seriously impair the strength or serviceability of the panels.
    5.4.6.2 Growth characteristics
    Tight knots in inner plies shall be permitted.
    In D grade faces or backs, any number of tight knots not larger than 63.5 mm (2-1/2 in) across
    the grain shall be permitted. However, an occasional tight knot larger than 63.5 mm (2-1/2 in)
    but not larger than 76.2 mm (3 in) measured across the grain, shall be permitted subject to the
    following provision:
    (a) Determine the Critical Section containing the knot. (See Section 2.14.)
    (b) Determine the aggregate width of all knots and knotholes occurring wholly within
    the Critical Section. Other open characteristics and growth characteristics are
    not included in this aggregate.
    (c) The knot is permitted if the aggregate width of all knots and knotholes in the
    Critical Section does not exceed 254 mm (10 in) in a 1220 mm (48 in) wide panel
    and proportionately for other panel widths.
    16
    5.4.6.3 Open characteristics
    Any number of knotholes up to 63.5 mm (2-1/2 in) across the grain shall be permitted. However,
    an occasional knothole larger than 63.5 mm (2-1/2 in) but not larger than 76.2 mm (3 in)
    measured across the grain shall be permitted subject to the following provision:
    (a) Determine the Critical Section containing the knothole. (See Section 2.14)
    (b) Determine the aggregate width of all knots and knotholes occurring wholly within
    the Critical Section. Other open characteristics and growth characteristics are
    not included in this aggregate.
    (c) The knothole is permitted if the aggregate width of all knots and knotholes in the
    Critical Section does not exceed 254 mm (10 in) in a 1220 mm (48 in) wide panel
    and proportionately for other panel widths.
    Knotholes in sanded panels shall not exceed 63.5 mm (2-1/2 in) across the grain in veneer
    thicker than 3.2 mm (1/8 in).
    Knotholes shall not exceed 88.9 mm (3-1/2 in) across the grain in veneers at least two plies
    removed from the face or back plies of C-D, D-D and C-D Plugged grades having five or more
    plies.
    Splits measured at a point 203 mm (8 in) from the end of the panel shall not exceed
    25.4 mm (1 in) in width, tapering to not more than 1.6 mm (1/16 in) where split runs full panel
    length; however, the maximum width within 203 mm (8 in) of the end of the panel (open end of
    split) shall not exceed the maximum width of knotholes permitted within the grade.
    Splits on panel faces and backs shall not exceed 6.4 mm (1/4 in) in width where located within
    25.4 mm (1 in) of parallel panel edge.
    Voids due to missing wood on panel backs not otherwise specified in Section 5.4.6.3 shall not
    exceed the maximum width of knotholes permitted in the grade and the length of such voids
    shall not exceed 152 mm (6 in).
    Wane not exceeding 203 mm (8 in) in length and the width permitted for open characteristics is
    allowed, providing that where occurring at edges of veneer sheets, panel ply separation due to
    wane shall not exceed the limit equivalent to that permitted for short and narrow inner plies in
    Section 5.8.3 for sanded panels, or Section 5.8.4 for unsanded or touch-sanded panels.
    5.4.6.4 White pocket
    Any area 610 mm (24 in) wide across the grain and 305 mm (12 in) long, in which light or heavy
    white pocket occurs, shall contain not more than three of the following characteristics, in any
    combination:
    (a) A 152 mm (6 in) width of heavy white pocket.
    (b) A 305 mm (12 in) width of light white pocket.
    17
    (c) One knot or knothole, 38.1 mm (1-1/2 in) to 63.5 mm (2-1/2 in), or two knots or
    knotholes, 25.4 mm (1 in) to 38.1 mm (1-1/2 in). Knots or knotholes less than
    25.4 mm (1 in) shall not be considered. Sizes of any knot or knothole shall be
    measured across the grain. Any repair in a white pocket area shall be
    considered for grading purposes as a knothole.
    5.5 Veneers and layers
    5.5.1 Veneer thickness
    Except as provided for in the following paragraphs, veneer shall be 2.5 mm (1/10 in) or thicker in
    panels with Performance Category of 3/8 rough (unsanded) thickness or over; 2.1 mm (1/12 in)
    or thicker in panels with Performance Category of less than 3/8 rough (unsanded) thickness. In
    no case shall veneers used in face or back layers be thicker than 6.4 mm (1/4 in), or veneers
    used in inner layers be thicker than 7.9 mm (5/16 in).
    Veneer of 2.1 mm (1/12 in) shall be permitted as crossbands in 5-ply, 5-layer panels with
    Performance Category of 15/32 and 1/2 and in parallel-laminated layers as provided for in
    5.5.2.
    Veneer of 1.6 mm (1/16 in) shall be permitted for any ply in 5-ply Exterior type panels with
    Performance Category of less than 15/32; as the center only in other 5-ply panels; and in a
    parallel laminated layer as provided for in Section 5.5.2.
    Face and back veneers shall be a minimum thickness of 3.2 mm (1/8 in) for panels with
    Performance Category of 19/32 5/8, 3, 4, and 5-ply, 3-layer panels of C-D, C-D Plugged, C-C,
    C-C Plugged and Underlayment grades.
    Further limitations on panel layup are provided in Section 5.8, Panel Constructions and
    Workmanship.
    The average veneer thickness shall conform to the limitations given in this Standard within a
    tolerance of ± 5% of the specified nominal thickness measured dry before layup.
    In lieu of veneer thickness requirements above, panels qualifying under workmanship provisions
    of Section 5.8 and performance testing in accordance with Section 5.8.6 or 5.8.7 shall be
    permitted.
    5.5.2 Parallel laminated layers
    Parallel-laminated outer layers shall only be used in C-C, C-D, D-D and Structural I C-C and
    C-D grades. Such layers shall consist of veneers 2.5 mm (1/10 in) or thicker in any combination
    not exceeding 6.4 mm (1/4 in) total layer thickness. The face and back plies or exposed plies of
    outer layers shall conform to the species group and grade requirements for faces and backs,
    respectively, of the panel grade. The unexposed plies of outer layers, or sub-face and sub-back
    plies, shall conform to the species group and grade requirements for inner plies of the panel
    grade as specified in Tables 2 and 3 and Section 5.6.5. The maximum split or gap in sub-faces
    and sub-backs shall be 6.4 mm (1/4 in) under the faces of Structural I C-C and C-D panels;
    12.7 mm (1/2 in) under the faces of C-C, C-D and D-D grades, and 12.7 mm (1/2 in) under D
    backs.
    18
    Parallel-laminated inner layers in any grade shall consist of veneers 1.6 mm (1/16 in) or thicker
    in any thickness combination not exceeding 11.1 mm (7/16 in) total layer thickness. Individual
    plies in such layers shall conform to the species group and grade requirements for inner plies of
    the panel grade.
    In lieu of veneer thickness requirements above, panels qualifying under workmanship provisions
    of Section 5.8 and performance testing in accordance with Section 5.8.6 or Section 5.8.7 shall
    be permitted.
    TABLE 2. EXPOSURE 1 PLYWOOD GRADES (PERMITS D GRADE VENEER)
    Minimum Veneer Quality
    Panel Grade Designations Face Back Inner Plies Surface
    N-N N N C Sanded 2 sides
    N-A N A C Sanded 2 sides
    N-B N B C Sanded 2 sides
    N-D N D D Sanded 2 sides
    A-A A A D Sanded 2 sides
    A-B A B D Sanded 2 sides
    A-D A D D Sanded 2 sides
    B-B B B D Sanded 2 sides
    B-D B D D Sanded 2 sides
    Underlayment(a) C Plugged D C & D Touch-sanded
    C-D Plugged C Plugged D D Touch-sanded
    Structural I C-D See 5.6.5 Unsanded(b)
    Structural I C-D Plugged, Underlayment See 5.6.5 Touch-sanded
    C-D C D D Unsanded(b)
    D-D(c) D D D Unsanded(b)
    (a) See Section 5.6.3 and Table 5 for special limitations.
    (b) See Section 5.8.4 for requirements.
    (c) Applicable only to panels qualified through performance testing per Section 5.8.6 (plus Section 6.2.2.3 of PS 2-
    18) or PS 2-18.
    5.5.3 Scarfed veneers
    Scarfed veneers shall be permitted for any face, back, or inner ply except as provided in
    Section 5.9. Scarfed joints shall not have a slope steeper than 1 to 8. Veneer in the scarf area
    shall not contain characteristics which reduce its effective cross section by more than 20%.
    Veneer scarfed joints shall be bonded with a moisture resistant adhesive.
    5.6 Panel grades
    The standard combination of the veneers described in Section 5.4 assembled into the various
    panel grades shall be as provided in Tables 2 and 3, with the additional requirements provided
    in Sections 5.6.1 through 5.6.7. The grain direction of the outer layers shall be either parallel or
    perpendicular to the long dimension of the panel.
    19
    TABLE 3. EXTERIOR PLYWOOD GRADES(a) (DOES NOT PERMIT D GRADE VENEER)
    Minimum Veneer Quality
    Panel Grade Designations Face Back Inner
    Plies
    Surface
    Marine (A-A, A-B, B-B, HDO, MDO) See 5.6.1 See regular grades
    Special Exterior (A-A, A-B, B-B, HDO, MDO) See 5.6.6 See regular grades
    A-A A A C Sanded 2 sides
    A-B A B C Sanded 2 sides
    A-C A C C Sanded 2 sides
    B-B (concrete form) B B C See 5.6.4
    B-C (concrete form) B C C See 5.6.4
    B-B B B C Sanded 2 sides
    B-C B C C Sanded 2 sides
    C-C Plugged(b) C Plugged C C Touch-sanded
    C-C C C C Unsanded(c)
    HDO-Industrial A-A, B-B, B-C C (d)
    HDO-Concrete Form(e) A-A, B-B, B-C C
    MDO-General B-B, B-C C
    MDO-Concrete Form(e) B-B, B-C C
    Special Overlays C C C — (a) Available also in Structural I classification as provided in Section 5.6.5.
    (b) See Section 5.6.3 and Table 5 for special limitations.
    (c) See Section 5.8.4 for requirements.
    (d) C Plugged for HDO-Industrial when intended for sign applications
    (e) For more clarification on concrete form grades, see Section 5.6.4.
    5.6.1 Marine
    Marine grades shall meet the requirements of Exterior plywood and shall be of one of the
    following grades: A-A, A-B, B-B, High Density Overlay, or Medium Density Overlay, all as
    modified in Sections 5.6.1.1 through 5.6.1.3.
    5.6.1.1 Species
    Only Group 1 Douglas-fir and Western Larch veneers shall be used.
    5.6.1.2 Veneers
    Grade A faces shall be limited to a total of nine single wood repairs in a 1220 mm by 2440 mm
    (48 x 96 in) sheet, or to a proportionate number in any other size as manufactured.
    All inner plies shall be B grade or better and shall be full length and width.
    All wood repairs shall be bonded with an adhesive meeting the Exterior performance
    requirements of Section 5.7.2 and, in addition, shall be set in the panel using a technique
    involving both heat and pressure.
    When the inner plies consist of two or more pieces of veneer, the edges shall be straight and
    square, and shall not overlap.
    5.6.1.3 Crossband gaps and edge splits
    Neither edge of a panel shall have any crossband gap or edge split in excess of 3.2 mm (1/8 in)
    wide. Crossband gaps and edge splits per 2440 mm (96 in) of crossband ply shall not exceed
    four in number. End splits and gaps on either end of a panel shall not exceed 3.2 mm (1/8 in) in
    aggregate width.
    There shall be no filling of crossband gaps and edge splits.
    20
    5.6.2 Decorative panels
    Specialty panels with decorative face and veneer treatments which, except for the special face
    treatment, meet all of the requirements of this Standard, including veneer qualities, adhesive
    bond performance and workmanship, shall be considered as conforming to this Standard. All
    grades in Tables 2 and 3 shall be permitted to be manufactured as decorative grades.
    An occasional butt joint used for decorative effect in veneer shall have a maximum width of
    152 mm (6 inches) and shall be limited to one panel face. Where butt joints occur, the
    aggregate width of all knots and knotholes and two-thirds the aggregate width of all repairs,
    including butt joints, shall not exceed 152 mm (6 in) in any area 305 mm (12 in) along the grain
    by 1220 mm (48 in) wide or proportionately for other widths.
    5.6.3 Underlayment
    Underlayment is plywood produced with touch sanded faces to the following requirements.
    5.6.3.1 Exposure 1 Underlayment.
    Face veneer shall be C-plugged grade 2.5 mm (1/10 in) or thicker before sanding. The veneer
    immediately adjacent to the face ply shall be C grade or better with no open characteristics over
    25.4 mm (1 in) across the grain; except that veneer immediately adjacent to the face ply shall be
    permitted to be D grade with open characteristics up to 63.5 mm (2-1/2 in) across the grain
    provided the face veneer is of Group 1 or 2 species of 4.2 mm (1/6 in) minimum thickness
    before sanding. Also see Table 5 requirements.
    5.6.3.2 Exterior Underlayment (C-C plugged or better).
    Face veneer shall be C-plugged grade or better 2.5 mm (1/10 in) or thicker before sanding. The
    veneer immediately adjacent to the face ply shall be C grade or better with no open
    characteristics over 25.4 mm (1 in) across the grain except that veneer immediately adjacent to
    the face ply shall be permitted to be C grade with open characteristics up to 38.1 mm (1-1/2 in)
    across the grain, provided the face veneer is of Group 1 or 2 species of 4.2 mm (1/6 in)
    minimum thickness before sanding. Also see Table 5 requirements.
    5.6.4 Concrete form panels
    Face veneers shall not be less than B grade and back veneers shall not be less than C grade.
    The face and back veneers shall be of the same species group. The face and back veneers
    shall be designated in the trademark. Inner plies shall be not less than “C” grade. This grade of
    plywood is produced in two classes, and panels of each class shall be identified accordingly.
    Non-overlaid panels shall be sanded two sides and have a mill-applied release agent unless
    otherwise agreed upon between buyer and seller. For non-overlaid panels, Western Larch shall
    be excluded from use in the face plies of concrete form plywood due to the excessive wood
    sugars that prohibit proper curing of concrete. Species shall be further limited as follows and
    are applicable also to High Density Overlaid Exterior and Medium Density Overlaid Exterior
    concrete form panels:
    (a) Class I — Faces of Group 1 species, crossband of Group 1 or Group 2 species,
    and centers of Group 1, 2, 3, or 4 species.
    (b) Class II — Faces of Group 1 or Group 2 species, and crossband and centers of
    Group 1, 2, 3, or 4 species; or, faces of Group 3 species of 3.2 mm (1/8 in)
    minimum thickness before sanding, crossband of Group 1, 2, or 3 species, and
    centers of Group 1, 2, 3, or 4 species.
    21
    5.6.5 Structural I panels
    These panels are especially designed for engineered applications such as structural
    components where design properties, including tension, compression, shear, cross-panel
    flexural properties and nail bearing are of significant importance. Structural I shall be produced
    as C-D, C-D Plugged, Underlayment or any Exterior grade (see Table 3). Structural I panels
    shall meet all other requirements in this Standard for the applicable types and grades and the
    additional requirements below:
    (a) All face, back and inner plies shall be Group 1 species as listed in Table 1
    (b) Special limitations applying to Structural I (C-D, C-D Plugged, Underlayment)
    grade panels are:
    • In D grade veneers, white pocket in any area larger than the size of the
    largest knothole, pitch pocket or split specifically permitted in D grade shall
    not be permitted in any ply
    • Sound tight knots in D grade shall not exceed 63.5 mm (2-1/2 in) measured
    across the grain, except as provided in Table 5
    • Plugs, including multiple repairs, shall not exceed 102 mm (4 in) in width.
    5.6.6 Special Exterior
    An Exterior panel that is produced from any species covered by this Standard. Except in regard
    to species, it shall meet all of the requirements for Marine panels (see Section 5.6.1) and be
    produced in one of the following grades: A-A, A-B, B-B, High Density Overlay, or Medium
    Density Overlay.
    5.6.7 Overlays
    For overlaid plywood, the grade designation for face and back, as given in Table 3, refers to the
    veneer directly beneath the overlay. All overlaid plywood shall be overlaid on two sides unless
    identified as having one working face as specified in section 7.3.c. When only one side is
    overlaid (or when a backer sheet is applied), the back shall be C or better. The surface of
    overlaid plywood shall be smooth, or uniformly textured, although some evidence of underlying
    grain shall be permitted.
    5.6.7.1 High Density Overlay – Concrete Form
    HDO Concrete Form plywood shall be manufactured with thermosetting phenolic resin
    impregnated cellulose-fiber sheet or sheets bonded to the working face. The overlay layer shall
    consist of a sheet or sheets, containing not less than 52% phenolic resin content, based on the
    volatile-free weight of fiber and resin. The thickness of resin-impregnated materials for each
    working face shall be not less than 0.30 mm (0.012 in) thick before pressing and shall weigh not
    less than 290 g per m2 (60 pounds per 1000 ft2
    ) in the ready-to-use condition. When the overlay
    layer is composed of MDO cushion sheet and HDO cap sheet (or sheets), the MDO sheet shall
    be not less than 34% phenolic resin content based on the volatile-free weight of resin and fiber,
    exclusive of bond line.
    5.6.7.2 High Density Overlay – Industrial
    HDO Industrial plywood is typically used for highway signs or industrial applications. HDOIndustrial plywood shall be manufactured with thermosetting phenolic resin impregnated
    cellulose-fiber sheet or sheets bonded to the working face. The overlay layer shall consist of a
    sheet or sheets, containing not less than 45% phenolic resin content based on the volatile-free
    weight of fiber and resin. The thickness of resin-impregnated materials for each working face
    22
    shall be not less than 0.30 mm (0.012 in) thick before pressing and shall weigh not less than
    290 g per m2 (60 pounds per 1000 ft2
    ) in the ready-to-use condition. When the overlay layer is
    composed of MDO cushion sheet and HDO cap sheet (or sheets), the MDO sheet shall be not
    less than 34% resin content based on the volatile-free weight of resin and fiber, exclusive of
    bond line.
    5.6.7.3 Medium Density Overlay – Concrete Form
    MDO Concrete Form plywood shall be manufactured with thermosetting phenolic resin
    impregnated cellulose-fiber sheet or sheets bonded to the working face. The overlay layer shall
    consist of a sheet or sheets, containing not less than 34% phenolic resin content based on the
    volatile-free weight of fiber and resin, but exclusive of bond line. The thickness of resinimpregnated materials for each working face shall be not less than 0.30 mm (0.012 in) thick
    after pressing and shall weigh not less than 280 g per m2 (58 pounds per 1000 ft2
    ) including both
    resin and fiber, but exclusive of bond line. Unless otherwise agreed upon between buyer and
    seller, MDO Concrete Form plywood shall be treated with a release agent.
    5.6.7.4 Medium Density Overlay – General
    MDO General plywood shall be manufactured with thermosetting phenolic resin impregnated
    cellulose-fiber sheet or sheets bonded to the working face. The overlay layer shall consist of a
    sheet or sheets, containing not less than 27% phenolic resin content based on the volatile-free
    weight of fiber and resin, but exclusive of bond line. The thickness of resin-impregnated
    materials for each working face shall be not less than 0.30 mm (0.012 in) thick after pressing
    and shall weigh not less than 280 g per m2 (58 pounds per 1000 ft2
    ) including both resin and
    fiber, but exclusive of bond line. The resin-treated facing on the finished product shall be
    suitable for painting.
    5.6.7.5 Special overlays
    These are surfacing materials having resin systems, resin-treated fiber materials, or special
    characteristics that do not fit the particular description of High Density or Medium Density
    overlays as given in Sections 5.6.7.1, 5.6.7.2, 5.6.7.3, or 5.6.7.4. Special Overlays shall meet
    the adhesive bond requirements for overlaid plywood. (See 5.7.2.2.) Although designed for a
    wide variety of uses, this overlaid plywood shall be Exterior, including the base panel, bond of
    overlay to the panel, and the overlay itself. Panels shall be identified as “Special Overlay.”
    5.7 Adhesive bond requirements for a panel or a lot
    The adhesive bond shall meet the requirements below.
    5.7.1 Exposure 1
    A panel shall be considered as meeting Exposure 1 adhesive bond requirements of this
    Standard if the test specimens taken from a panel average 80% wood failure or greater when
    tested in accordance with Section 6.1.3. For qualification purposes, specimens from at least 20
    panels shall be sampled.
    Lots represented by test panels shall be considered as meeting the requirements of this
    Standard if the requirements of (a) and (b) are met:
    (a) The average wood failure of all test specimens, regardless of the number of
    panels tested, shall be not less than 80%,
    (b) And:
    23
11. When at least 10 panels are tested, at least 90% of the panels
    represented by the test pieces shall have 60% wood failure or better, and
12. When at least 20 panels are tested, at least 95% of the panels
    represented by the test pieces shall have 30% wood failure or better.
13. When fewer than 10 panels are tested, all panels represented by the test
    pieces shall have 60% wood failure or better.
    The requirements of Section 5.7.1 are applicable separately and independently to the results
    obtained from the vacuum-pressure test (Section 6.1.3.2) and the boiling test (Section 6.1.3.3).
    Specimens cut through localized characteristics permitted in the grade shall be discarded. Test
    specimens showing delamination in excess of 3.2 mm (1/8 in) deep and 25.4 mm (1 in) long
    shall be rated as zero (0)% wood failure.
    5.7.1.1 Heat performance
    Panels shall meet the heat performance requirements for Exterior adhesives. (See Section
    5.7.2.1.)
    5.7.2 Exterior
    When tested in accordance with Section 6.1.3, Exterior plywood shall be considered as meeting
    the adhesive bond requirements of this Standard if the test specimens taken from a panel
    average 85% wood failure or greater. For qualification purposes, specimens from at least 20
    panels shall be sampled.
    Lots represented by test panels shall be considered as meeting the requirements of this
    Standard if the minimum requirements of (a) and (b) are met:
    (a) The average wood failure of all test specimens, regardless of the number of
    panels tested, shall be not less than 85%,
    (b) And:
14. When at least 4 panels are tested, at least 75% of the panels represented
    by the test pieces shall have 80% wood failure or better; and
15. When at least 10 panels are tested, at least 90% of the panels
    represented by the test pieces shall have 60% wood failure or better; and
16. When at least 20 panels are tested, at least 95% of the panels
    represented by the test pieces shall have 30% wood failure or better.
17. When fewer than 4 panels are tested, all panels represented by the test
    pieces shall have 80% wood failure or better.
    The requirements of Section 5.7.2 are applicable separately and independently to the results
    obtained from the vacuum-pressure test (Section 6.1.3.2) and the boiling test (Section 6.1.3.3).
    Specimens cut through localized characteristics permitted in the grade shall be discarded. Test
    specimens showing delamination in excess of 3.2 mm (1/8 in) deep and 25.4 mm (1 in) long
    shall be rated as zero (0)% wood failure.
    24
    5.7.2.1 Heat performance
    Exterior plywood shall be considered as meeting the requirements of this section if there is no
    delamination in any specimen, except when occurring at a localized characteristic permitted in
    the grade when tested in accordance with Section 6.1.3.4. When testing overlaid plywood,
    blisters or bubbles in the surface caused by combustion shall not be considered as
    delamination.
    5.7.2.2 Overlaid plywood
    The bond between veneers of overlaid plywood as well as the bond between the overlay and
    the base panel shall meet the wood failure requirements described in Section 5.7.2 for Exterior
    plywood. In evaluating specimens for separation of the resin-treated face from the plywood,
    fiber failure shall be considered the same as wood failure.
    5.8 Panel constructions and workmanship
    Constructions for all panels shall conform to the minimum number of plies and layers as set
    forth in Table 4. The proportion of wood with grain perpendicular to panel face grain shall be
    not less than 33% nor more than 70% of the total panel thickness. The combined thickness of
    inner layers in panels having 4 or more plies shall be not less than 45% of the total panel
    thickness. For application of these requirements, the panel thickness shall be the actual
    finished panel thickness and the veneer thickness shall be the dry veneer thickness before
    layup.
    The grain of all layers shall be perpendicular to the grain of adjacent layers and to the ends or
    edges of the panel. The entire area of each contacting surface of the adjacent plies, including
    repairs, shall be bonded with an adhesive in a manner to assure compliance with the
    performance requirements for its type as set forth in the test described in Section 6.
    For the purpose of veneer repairing or edge joining, strings, ribbons, or tapes up to 9.5 mm
    (3/8 in) maximum width can occur in a bond line and shall be considered as allowable localized
    characteristics in the evaluation of bond line test specimens. Wider strings, ribbons, or tapes
    shall not be used for veneer repairing or joining unless they are pre-qualified to show bonding
    equal to the required bonding for the panel. Bond line test specimens cut to include the strings,
    ribbons, or tapes wider than 9.5 mm (3/8 in) shall not be discarded because of the presence of
    these materials.
    Veneer strips shall not be joined by string stitching.
    Rough or unsanded plywood shall be permitted to have paper tape on either face or back, or
    both; except that, in C-C Exterior, no tape used for veneer splicing shall be permitted.
    Shims or strips of veneer shall not be used to repair panel edge voids. However, filling of
    permissible edge voids with synthetic fillers neatly applied shall be allowed, except as prohibited
    in Marine grades. (See Section 5.6.1.) Staples or pins of metal or synthetic material shall be
    prohibited.
    Where face or back plies consist of more than one piece of edge joined veneer, gaps between
    adjacent pieces shall be graded as splits.
    End butt joints shall only be used under the following conditions:
    (a) Decorative grades as provided in Section 5.6.2.
    25
    (b) Butt joints having a total aggregate width not exceeding the width of the panel
    shall occur in the center ply of 5-ply, 5-layer panels. The butt joints shall be
    perpendicular to the grain of the panel face and back plies. The use of buttjointed centers shall be allowed in Exposure 1 sanded grades in panels with
    Performance Category up to and including 1/2, and in D-D, C-D and C-D
    Plugged panels with Performance Category up to and including 3/4 . End butt
    joints shall not be used in Structural I panels. Panels with butt joints in center
    plies shall be marked “butt-jointed center” as specified in Section 7.3.
    Plywood shall be free from blisters, laps and other characteristics, except as expressly
    permitted in Section 5.8 and its subsections. Panels shall have no continuous holes or through
    openings from face to back.
    5.8.1 Crossband gaps and center gaps
    Crossband gaps or center gaps, except as noted for plugged crossband and jointed crossband,
    shall not exceed 25.4 mm (1 in) in width for a depth of 203 mm (8 in) measured from panel
    edge. The average of all gaps occurring in a panel shall not exceed 12.7 mm (1/2 in). Where
    inner layers are thicker than 6.4 mm (1/4 in), gaps in the laminated plies shall be offset
    25.4 mm (1 in) if over 6.4 mm (1/4 in) wide.
    Where plugged inner plies are specified, inner plies shall be of C Plugged veneer, and gaps
    between adjacent pieces of inner plies shall not exceed 12.7 mm (1/2 in).
    Where jointed inner plies are specified, gaps between pieces of inner plies shall not exceed
    9.5 mm (3/8 in), and the average of all gaps occurring in a panel shall not exceed 4.8 mm
    (3/16 in).
    26
    TABLE 4. PANEL CONSTRUCTIONS (MINIMUM NUMBER OF PLIES AND LAYERS)
    Panel Grades
    Finished Panel
    Performance Category Range
    Minimum
    Number
    of Plies
    Minimum
    Number
    of Layers
    Exterior
    Marine
    Special Exterior (See 5.6.6 )
    B-B Concrete form
    B-C Concrete form
    HDO Industrial A-A, B-B, B-C
    HDO Concrete Form A-A, B-B, B-C
    MDO Concrete Form B-B, B-C
    Through 3/8
    Over 3/8 , through 3/4
    Over 3/4
    3
    5
    7
    3
    5
    7
    Exposure 1
    N-N, N-A, N-B, N-D, A-A, A-B,
    A-D, B-B, B-D
    Structural I (C-D, C-D Plugged
    and Underlayment)
    Exterior
    A-A, A-B, A-C, B-B, B-C
    Structural I (C-C and
    C-C Plugged) (See 5.6.5)
    MDO General B-B, B-C
    Special Overlays
    Through 3/8
    Over 3/8 , through 1/2
    Over 1/2 , through 7/8
    Over 7/8
    3
    4
    5
    6
    3
    3
    5
    5
    Exposure 1
    Underlayment
    Exterior
    C-C Plugged
    Through 1/2
    Over 1/2 , through 3/4
    Over 3/4
    3
    4
    5
    3
    3
    5
    Exposure 1
    C-D
    C-D Plugged
    D-D
    Exterior
    C-C
    Through 5/8
    Over 5/8 , through 3/4
    Over 3/4
    3
    4
    5
    3
    3
    5
    5.8.2 Veneer requirements
    The veneers used in each ply of each panel and the completed panel shall conform with the
    applicable veneer grade and with the construction and workmanship requirements given herein.
    Additionally, in recognition of the requirements of selected end uses, the type and frequency of
    specific characteristics shall be further limited for grades in Table 5.
    27
    TABLE 5. CHARACTERISTICS PROHIBITED OR RESTRICTED IN CERTAIN PANEL GRADES
    Panel Grade
    Designation Description and Number of Characteristics Per Panel
    N-N, N-A No crossband laps adjacent to faces and backs
    N-B No crossband laps adjacent to N faces
    No more than 2 crossband laps adjacent to B grade side (Section 5.8.3)
    Laps are limited to 4.8 mm (3/16 in)
    N-D No crossband laps adjacent to faces
    No more than a total of 2 of any combination of the following:
    — Knothole in D veneer over 63.5 mm (2-1/2 in) but not over 76.2 mm (3 in)
    — Split in D veneer over 12.7 mm (1/2 in) but not over 25.4 mm (1 in)
    — Crossband lap adjacent to backs
    Underlayment
    and C-C
    Plugged
    No knotholes in veneer adjacent to face over 25.4 mm (1 in) across the grain where C grade is required per
    Tables 2 and 3
    No knotholes in veneer adjacent to face over 63.5 mm (2-1/2 in) where D grade is permitted or over 38.1 mm
    (1-1/2 in) where C grade is permitted per 5.6.3
    No laps adjacent to face
    Structural I C-D No splits in faces over 6.4 mm (1/4 in)
    No splits in backs over 12.7 mm (1/2 in)
    No more than a total of 2 of any combination of the following:
    — Knothole in C veneer over 25.4 mm (1 in) but not over 38.1 mm (1-1/2 in)
    — Knot in D backs over 63.5 mm (2-1/2 in) but not over 76.2 mm (3 in)
    — Knothole in D veneer over 63.5 mm (2-1/2 in) but not over 76.2 mm (3 in)
    — Crossband lap adjacent to faces (See Section 5.8.4)
    — Crossband lap adjacent to backs (See Section 5.8.4)
    Structural I C-D
    Plugged
    No splits in backs over 12.7 mm (1/2 in)
    No more than a total of 2 of any combination of the following:
    — Knot in D backs over 63.5 mm (2-1/2 in) but not over 76.2 mm (3 in)
    — Knothole in D veneer over 63.5 mm (2-1/2 in) but not over 76.2 mm (3 in)
    — Crossband lap adjacent to faces (See Section 5.8.4)
    — Crossband lap adjacent to backs (See Section 5.8.4)
    Structural I
    Underlayment
    No knotholes in core veneer next to face over 25.4 mm (1 in)
    No crossband laps adjacent to faces
    No splits in backs over 12.7 mm (1/2 in)
    No more than a total of 2 of any combination of the following:
    — Knot in D backs over 63.5 mm (2-1/2 in) but not over 76.2 mm (3 in)
    — Knothole in D veneer over 63.5 mm (2-1/2 in) but not over 76.2 mm (3 in)
    — Crossband lap adjacent to backs (See Sections 5.8.3, 5.8.4)
    5.8.3 Sanded panels
    Unless otherwise specified, sanded plywood shall be sanded on two sides. Sanding
    characteristics for N, A, B, and C Plugged faces shall be as given in Section 5.4. Exposed N, A,
    and B veneer surfaces of panels shall have the bark or tight surface out. Plies directly under the
    surface of overlaid panels are not considered exposed veneers. Faces and backs of panels
    shall be full width and full length; except that C grade and D grade backs shall be permitted to
    be narrow on one edge or short on one end only, but by not more than 3.2 mm (1/8 in) for half
    the panel length or width. Inner plies shall be full width and length; except that panels other
    than Marine shall be permitted to have one edge or end void not exceeding 3.2 mm (1/8 in) in
    depth and 203 mm (8 in) in length per panel. Except as otherwise specified in Table 5 for
    specific panel grade designations, crossband veneers not exceeding 3.2 mm (1/8 in) in
    thickness shall be permitted to be lapped but by not more than 4.8 mm (3/16 in) when adjacent
    to faces, or 12.7 mm (1/2 in) when adjacent to backs, and provided such laps create no
    adjacent visible openings. Sanding characteristics resulting from crossband laps shall not be
    permitted in panel faces.
    28
    5.8.4 Unsanded and touch-sanded panels
    Grade C or D veneers shall be permitted to be lapped by not more than 12.7 mm (1/2 in)
    provided such laps shall create no adjacent visible opening. Additional limitations on laps
    adjacent to panel faces and backs are included in Table 5. All plies of C-D and D-D panels shall
    be full length and full width except that no more than half the length of one edge nor half the
    width of one end shall be permitted to contain short or narrow plies, provided:
    (a) Such plies shall not be short or narrow by more than 4.8 mm (3/16 in) except that
    crossbands shall be permitted to be short by 12.7 mm (1/2 in) and centers shall
    be permitted to be narrow by 12.7 mm (1/2 in) provided they taper to within
    4.8 mm (3/16 in) or less of the panel edge in 203 mm (8 in).
    (b) When short or narrow by more than 4.8 mm (3/16 in), the aggregate area in the
    plane of the plies of such edge characteristics shall not exceed 39 cm2 (6 in2
    ) in
    the entire panel.
    (c) Such edge characteristics shall not occur in more than one ply at any panel cross
    section.
    In grades other than C-D and D-D, backs shall be permitted to be narrow on one edge or short
    on one end only, but by not more than 3.2 mm (1/8 in) for half the panel length or width; inner
    plies shall be full width and length except that one edge or end void not exceeding 3.2 mm
    (1/8 in) in depth and 203 mm (8 in) in length per panel, shall be acceptable.
    Panels manufactured as C-C, C-D, D-D, Structural I C-C and Structural I C-D shall not be
    surface textured. Panels manufactured as C-C, C-D, D-D, Structural I C-C and Structural I C-D
    that are sanded or touch-sanded shall meet all applicable requirements for C-C, C-D or D-D and
    the finished face and back veneers after sanding shall each have a minimum net thickness
    equal to 90% of the applicable thickness in Table 6 or in the mill specification. (See Section
    5.8.7.3.)
    For touch sanded panels, indents (see Section 2.26) shall be considered as an open
    characteristic.
    29
    TABLE 6. SPAN RATINGS FOR SHEATHING AND SINGLE-FLOOR PANELS BASED ON PRESCRIPTIVE
    SPECIFICATIONS (FOR SPECIAL PLY-LAYER AND SPECIES REQUIREMENTS APPLICABLE TO STRUCTURAL I
    PANELS, SEE SECTION 5.6.5 AND TABLE 4. FOR CROSSBAND AND TOTAL INNER PLY THICKNESS PROPORTION
    REQUIREMENTS, SEE SECTION 5.8.)
    Minimum Face & Back Veneer Thickness
    Before Pressing, for Species Group(b)
    Span
    Rating
    (a) Panel
    Performance Category
    Minimum
    Number
    of PliesLayers 1 2 3 4
    Inner Ply
    Species
    Group
    Sheathing Panels (C-D, C-C)
    12/0 5/16 3-3 2.1 mm (1/12 in) 2.1 mm (1/12 in) 2.1 mm (1/12 in) 2.1 mm (1/12 in) 1, 2, 3 or 4
    16/0 5/16
    11/32
    3-3
    3-3
    2.1 mm (1/12 in)
    2.1 mm (1/12 in)
    2.1 mm (1/12 in)
    2.1 mm (1/12 in)
    2.1 mm (1/12 in)
    2.1 mm (1/12 in)
    (c)
    2.1 mm (1/12 in)
    1, 2, 3 or 4
    1, 2, 3 or 4
    20/0(e) 5/16
    11/32
    3/8
    3-3
    3-3
    3-3
    2.1 mm (1/12 in)
    2.1 mm (1/12 in)
    2.5 mm(1/10 in)
    (c)
    2.1 mm (1/12 in)
    2.5 mm (1/10 in)
    (c)
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    (c)
    (c)
    2.5 mm (1/10 in)
    1, 2, 3 or 4
    1, 2, 3 or 4
    1, 2, 3 or 4
    24/0 3/8
    13/32
    1/2
    3-3
    3-3
    3-3
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    (c)
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    (c)
    (c)
    2.5 mm (1/10 in)
    (c)
    (c)
    2.5 mm (1/10 in)
    1, 2, 3 or 4
    1, 2, 3 or 4
    1, 2, 3 or 4
    32/16 1/2
    17/32
    5/8
    3-3
    3-3
    3-3
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    (d)
    4.2 mm (1/6 in)
    2.5 mm (1/10 in)
    (d)
    (c)
    4.2 mm (1/6 in)
    (d)
    (c)
    (c)
    (d)
    1, 2, 3 or 4
    1, 2, 3 or 4
    1, 2, 3 or 4
    40/20(e) 5/8
    21/32
    3/4
    25/32
    3-3
    3-3
    4-3
    4-3
    (d)
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    4.2 mm (1/6 in)
    3.2 mm (1/8 in)
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    (c)
    4.2 mm (1/6 in)
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    (c)
    (c)
    3.2 mm (1/8 in)
    2.5 mm (1/10 in)
    1, 2, 3 or 4
    1, 2, 3 or 4
    1, 2, 3 or 4
    1, 2, 3 or 4
    48/24 3/4
    25/32
    7/8
    29/32
    4-3
    4-3
    5-5
    5-5
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    4.2 mm (1/6 in)
    3.2 mm (1/8 in)
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    (c)
    4.2 mm (1/6 in)
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    (c)
    (c)
    (c)
    3.2 mm (1/8 in)
    1, 2, 3 or 4
    1, 2, 3 or 4
    1, 2, 3 or 4
    1, 2, 3 or 4
    Single-Floor Panels (UNDERLAYMENT, C-C Plugged)
    16 o.c. 1/2
    19/32
    5/8
    3-3
    4-3
    4-3
    2.5 mm (1/10 in)
    (d)
    (d)
    (c)
    (d)
    (d)
    (c)
    (d)
    (d)
    (c)
    4.2 mm (1/6 in)
    (d)
    1, 2, 3 or 4
    1, 2, 3 or 4
    1, 2, 3 or 4
    20 o.c.(e) 19/32
    5/8
    23/32
    3/4
    4-3
    4-3
    4-3
    4-3
    (d)
    (d)
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    4.2 mm (1/6 in)
    3.2 mm (1/8 in)
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    (c)
    4.2 mm (1/6 in)
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    (c)
    (c)
    3.2 mm (1/8 in)
    2.5 mm (1/10 in)
    1, 2, 3 or 4
    1, 2, 3 or 4
    1, 2, 3 or 4
    1, 2, 3 or 4
    24 o.c. 23/32
    3/4
    7/8
    4-3
    4-3
    5-5
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    2.5 mm (1/10 in)
    4.2 mm (1/6 in)
    3.2 mm (1/8 in)
    2.5 mm (1/10 in)
    4.8 mm (3/16 in)
    4.2 mm (1/6 in)
    2.5 mm (1/10 in)
    (c)
    (c)
    3.2 mm (1/8 in)
    1, 2, 3 or 4
    1, 2, 3 or 4
    1, 2, 3 or 4
    48 o.c. 1-1/8
    1-1/8
    1-1/8
    1-1/8
    7-5
    7-5
    7-7
    7-7
    3.2 mm (1/8 in)
    3.6 mm (1/7 in)
    2.5 mm (1/10 in)
    3.2 mm (1/8 in)
    4.2 mm (1/6 in)
    4.2 mm (1/6 in)
    4.2 mm (1/6 in)
    4.2 mm (1/6 in)
    (c)
    (c)
    4.8 mm (3/16 in)
    4.8 mm (3/16 in)
    (c)
    (c)
    (c)
    (c)
    1 or 2
    1, 2 or 3
    1
    1, 2 or 3
    (a) See Section 5.8.5 for description.
    (b) Intermixing between species groups and/or thicknesses in the faces and backs of panels is permitted. Use the lowest applicable span rating
    to identify the panel. Also see Section 5.5.1.
    (c) Not permitted.
    (d) A minimum of 3.2 mm (1/8 in) for 3, 4 and 5-ply 3-layer panels per 5.5.1. A minimum of 2.5 mm (1/10 in) for 5-ply 5-layer panels.
    (e) The “20”span designation is intended for spans of 19.2 inch.
    5.8.5 Span ratings for panels
    Grade-trademarking of C-C, C-D, D-D, Structural I C-C, Structural I C-D, and of C-C Plugged
    and Underlayment to be used as combination subfloor-underlayment (single floor) shall include
    a “span rating.” The numbers are presented as a fraction in the marking of sheathing grades of
    plywood, and as a single number for C-C Plugged and Underlayment. They describe the
    maximum spans in inches under normal use conditions and are in accordance with commonly
    accepted criteria. Panels for which there is no span rating shall be identified by largest species
    group number of the face and back, or by the span rating of the next thinner comparable panel.
    30
    For sheathing, the left-hand number shall refer to spacing of roof framing, and the right-hand
    number shall relate to spacing of the floor framing. The single number for Underlayment and
    C-C Plugged refers to spacing of the floor framing in single floor applications. Actual maximum
    spans are established by local building codes.
    When used as single floor, panels shall also meet the grade requirements of Section 5.6.3.
    The span rating number is related to species and thickness of the panel face and back veneers,
    and panel Performance Category. It shall be established by either procedure (a) or (b):
    (a) By specification as detailed in Table 6, or
    (b) By performance testing to satisfy the strength, stiffness and bond criteria as
    detailed in Section 5.8.6. Such performance testing shall be performed by a
    qualified testing agency, as described in Section 7.2.
    5.8.6 Performance testing qualification requirements for span-rated panels
    5.8.6.1 General
    Acceptance of performance tested plywood under this Standard is based upon testing of panel
    strength, stiffness and bond performance. Panels selected for testing shall be of near minimum
    grade and near minimum thickness. Panel average thickness shall be established in
    accordance with Section 5.10.2. All provisions of veneer grade and panel workmanship are
    applicable.
    5.8.6.2 Performance testing
    Panels qualified by performance testing shall satisfy the criteria called for in Section 5.8.6 when
    tested in accordance with Sections 5.8.6.3 and 5.8.6.4.
    5.8.6.3 Structural performance
    Concentrated loads
    Test a maximum of 20 specimens taken from at least 10 panels. Ten specimens (taken from at
    least five panels) for each test exposure condition shall be evaluated for both concentrated
    static and impact loads according to Section 6.2.1. Requirements are found in Table 7. If
    additional tests are needed, they shall also consist of 10 specimens, and the results of the two
    10-specimen sets shall be combined. Only one additional test set is allowed. If the combined
    results meet or exceed the minimum passing rate, the sample passes.
    Deflection – The initial test set consists of 10 specimens.
    The average deflection shall not be greater than the appropriate requirement in Table 7.
    • If no more than one value is above the requirement, the sample passes.
    • If two or three values are above the requirement, test an additional set.
    • If four or more values are above the requirement, the sample fails.
    • If ten additional specimens are tested, the combined passing rate shall be at least 85%.
    31
    Ultimate load – The initial test set consists of 10 specimens.
    The average load shall not be less than the appropriate requirement in Table 7.
    • If all of the values meet or exceed the requirement, the sample passes.
    • If one of the values is below the requirement, test an additional set.
    • If two or more values are below the requirement, the sample fails.
    • If ten additional specimens are tested, the combined passing rate shall be at least 95%.
    Uniform loads
    Test a maximum of 20 specimens taken from at least 10 panels. Ten specimens (taken from at
    least five panels) for each test exposure condition shall be evaluated for uniform load capacity
    according to Section 6.2.2. Test requirements are found in Table 8. If additional tests are
    needed, they shall also consist of 10 specimens, and the results of the two 10-specimen sets
    shall be combined. Only one additional test set is allowed. If the combined results meet or
    exceed the minimum passing rate, the sample passes.
    Deflection – The average deflection shall not be greater than that specified. The initial test
    consists of 10 specimens.
    • If the average value is below the requirement, the sample passes.
    • If the average value is above the requirement, test an additional set.
    • If the average value based on combined results is above the requirement, the sample
    fails.
    Ultimate load – The initial test consists of 10 specimens. The average load shall not be less
    than the appropriate requirement in Table 8.
    • If all of the values meet or exceed the requirement, the sample passes.
    • If one of the values is below the requirement, test an additional set.
    • If two or more values are below the requirement, the sample fails.
    • If ten additional specimens are tested, the combined passing rate shall be at least 95%.
    32
    TABLE 7. CONCENTRATED STATIC AND IMPACT TEST PERFORMANCE CRITERIA
    FOR PANELS TESTED ACCORDING TO SECTION 6.2.1 (SEE SECTION 5.8.6.3
    FOR PASS/FAIL CRITERIA)
    Performance Criteria
    Ultimate Load
    End Use – Span
    Rating
    Test Exposure
    Conditions(a)
    Static Following Impact(b)
    Deflection
    Under 0.89 kN (200 lbf) Load
    kN lbf kN lbf mm in
    Roof – 16 Dry
    Wet 1.78 400 1.33 300 11.1(c)(d) 0.438(c)(d)
    Roof – 20(f) Dry
    Wet 1.78 400 1.33 300 11.9(c)(d) 0.469(c)(d)
    Roof – 24 Dry
    Wet 1.78 400 1.33 300 12.7(c)(d) 0.500(c)(d)
    Roof – 32 Dry
    Wet 1.78 400 1.33 300 12.7(c)(d) 0.500(c)(d)
    Roof – 40 Dry
    Wet 1.78 400 1.33 300 12.7(c)(d) 0.500(c)(d)
    Roof – 48 Dry
    Wet 1.78 400 1.33 300 12.7(c)(d) 0.500(c)(d)
    Roof – 54 Dry
    Wet 1.78 400 1.33 300 12.7(c)(d) 0.500(c)(d)
    Roof – 60 Dry
    Wet 1.78 400 1.33 300 12.7(c)(d) 0.500(c)(d)
    Subfloor – 16 Dry
    Wet/Redry 1.78 400 1.78 400 4.8(c) 0.188(c)
    Subfloor – 20(f) Dry
    Wet/Redry 1.78 400 1.78 400 5.6(c) 0.219(c)
    Subfloor – 24 Dry
    Wet/Redry 1.78 400 1.78 400 6.4(c) 0.250(c)
    Subfloor – 32 Dry
    Wet/Redry 2.45 550 1.78 400 5.3(c) 0.207(c)
    Subfloor – 48 Dry
    Wet/Redry 2.45 550 1.78 400 8.0(c) 0.313(c)
    Single Floor – 16 Dry
    Wet/Redry 2.45 550 1.78 400 2.0(e) 0.078(e)
    Single Floor –
    20(f)
    Dry
    Wet/Redry 2.45 550 1.78 400 2.4(e) 0.094(e)
    Single Floor – 24 Dry
    Wet/Redry 2.45 550 1.78 400 2.7(e) 0.108(e)
    Single Floor – 32 Dry
    Wet/Redry 3.11 700 1.78 400 2.2(e) 0.088(e)
    Single Floor – 48 Dry
    Wet/Redry 3.11 700 1.78 400 3.4(e) 0.133(e)
    (a) Wet/redry shall be exposure to three days of continuous wetting, followed by testing dry. Wet
    conditioning shall be exposure to three days of continuous wetting, then tested wet. Dry shall be within
    +/- 3% of the as-shipped moisture content.
    (b) Impact shall be 102 N•m (75 lbf•ft) for span ratings up to 24, 122 N•m (90 lbf•ft) for 32, 163 N•m
    (120 lbf•ft) for 40, and 203 N•m (150 lbf•ft) for 48 and greater.
    (c) Criteria apply under static concentrated load. They do not apply following impact.
    (d) Deflection after wet conditioning not applicable.
    (e) Criteria apply under static concentrated load and following impact.
    (f) The “20” span designation is intended for spans of 19.2 inch.
    33
    TABLE 8. UNIFORM LOAD PERFORMANCE CRITERIA FOR PANELS TESTED
    ACCORDING TO SECTION 6.2.2
    (SEE SECTION 5.8.6.3 FOR PASS/FAIL CRITERIA)
    Performance Criteria(b)
    Ultimate
    Uniform Load
    End Use –
    Span Rating
    Test Exposure
    Conditions(a) Average Deflection Under Load kPa lbf/ft2
    Roof – 16 Dry 1.7 mm at 1.68 kPa (0.067 in at 35 lbf/ft2) 7.2 150
    Roof – 20 (c) Dry 2.0 mm at 1.68 kPa (0.080 in at 35 lbf/ft2) 7.2 150
    Roof – 24 Dry 2.5 mm at 1.68 kPa (0.100 in at 35 lbf/ft2) 7.2 150
    Roof – 32 Dry 3.4 mm at 1.68 kPa (0.133 in at 35 lbf/ft2) 7.2 150
    Roof – 40 Dry 4.2 mm at 1.68 kPa (0.167 in at 35 lbf/ft2) 7.2 150
    Roof – 48 Dry 5.1 mm at 1.68 kPa (0.200 in at 35 lbf/ft2) 7.2 150
    Roof – 54 Dry 5.7 mm at 1.68 kPa (0.225 in at 35 lbf/ft2) 7.2 150
    Roof – 60 Dry 6.4 mm at 1.68 kPa (0.250 in at 35 lbf/ft2) 7.2 150
    Subfloor – 16 Dry
    Wet/Redry
    1.1 mm at 4.79 kPa (0.044 in at 100 lbf/ft2) 15.8 330
    Subfloor – 20(d) Dry
    Wet/Redry
    1.3 mm at 4.79 kPa (0.053 in at 100 lbf/ft2) 15.8 330
    Subfloor – 24 Dry
    Wet/Redry
    1.7 mm at 4.79 kPa (0.067 in at 100 lbf/ft2) 15.8 330
    Subfloor – 32 Dry
    Wet/Redry
    2.2 mm at 4.79 kPa (0.088 in at 100 lbf/ft2) 15.8 330
    Subfloor – 48 Dry
    Wet/Redry
    3.4 mm at 3.83 kPa (0.133 in at 80 lbf/ft2) 10.8 225
    Single Floor – 16 Dry
    Wet/Redry
    1.1 mm at 4.79 kPa (0.044 in at 100 lbf/ft2) 15.8 330
    Single Floor – 20(c) Dry
    Wet/Redry
    1.3 mm at 4.79 kPa (0.053 in at 100 lbf/ft2) 15.8 330
    Single Floor – 24 Dry
    Wet/Redry
    1.7 mm at 4.79 kPa (0.067 in at 100 lbf/ft2) 15.8 330
    Single Floor – 32 Dry
    Wet/Redry
    2.2 mm at 4.79 kPa (0.088 in at 100 lbf/ft2) 15.8 330
    Single Floor – 48 Dry
    Wet/Redry
    3.4 mm at 3.83 kPa (0.133 in at 80 lbf/ft2) 10.8 225
    (a)Wet/Redry shall be exposure to three days of continuous wetting, followed by testing dry. Dry shall be within 3% of
    the as shipped moisture content.
    (b)The panel strength axis shall be across supports, unless otherwise specified.
    (c)The “20” span designation is intended for spans of 19.2 inch.
    5.8.6.4 Bond performance
    Panels shall be classed as “Exposure 1” or “Exterior”.
    Exposure 1 — Panels rated as “Exposure 1” shall be so identified and shall satisfy the bond
    requirements as specified in Section 5.7.1.
    Exterior — Panels rated as “Exterior”’ shall be so identified and shall satisfy the bond
    requirements specified in Section 5.7.2.
    34
    5.8.6.5 Product evaluation
    Mill specification — Upon conformance with the appropriate requirements of Sections 5.8.6.3
    and 5.8.6.4, a manufacturing specification unique to the product and mill shall be written based
    on product evaluation. This specification shall be used for quality assurance purposes by the
    manufacturer and the qualified testing agency, according to Section 5.8.7.3. Product evaluation
    will be accomplished on the same lot supplied by the manufacturer for qualification testing.
    Reference values shall be established during product evaluation or from applicable performance
    requirements in this Standard. The mill specification shall contain the following information:
    Panel construction — Panels shall be defined as to veneer species and construction.
    Thickness — The reference value shall be the average panel thickness less 1.932 standard
    deviations (the 95% lower tolerance limit at 75% confidence) for twenty panels as sampled
    under Section 5.8.6.1.
    Mechanical properties
    Bending stiffness — Twenty tests (specimens taken from at least ten panels) shall be
    evaluated for bending stiffness both along and across the major panel axis according to the
    procedures of Section 6.2.3. The reference value for each panel direction shall be the lower
    value of a 90% confidence interval established on the mean.
    Bending strength — Ten tests (specimens taken from ten different panels) shall be tested for
    maximum bending moment both along and across the major panel axis according to the
    procedures of Section 6.2.3. The reference values for each panel direction will be the minimum
    observed value, or the sample mean less 1.8 times the sample standard deviation, whichever is
    the higher value.
    5.8.7 Performance testing qualification requirements for other than span-rated panels
    5.8.7.1 General
    Panels using species as provided in Section 5.2.4 shall be qualified for use under this Standard
    based upon testing of panel strength and stiffness in accordance with Section 5.8.7.2. Results
    of testing shall establish a Group classification for use as required in Section 7.3 (a). Group
    classification established by panel testing shall be determined by the largest Group number
    obtained from all performance tests.
    5.8.7.2 Performance testing
    Bending stiffness — A minimum of twenty tests (specimens taken from at least ten panels)
    shall be evaluated for bending stiffness both along and across the major panel axis according to
    the procedures of Section 6.2.3. At least 90% of specimens tested along the major axis shall
    meet the minimum stiffness value along the major axis given in Table 9 for the Performance
    Category tested.
    35
    TABLE 9. SPECIES GROUP CLASSIFICATION TEST CRITERIA FOR OTHER
    THAN SPAN-RATED PANELS
    Shear Through Stress Along (Parallel to Face)
    Performance
    Category Group
    Thickness
    Strength Bending Stiffness Bending Strength
    Planar Shear
    Strength
    kN/m (lbf/in) kN•m2/m (lbf•in2/ft) kN•m/m (lbf•in/ft) kN/m (lbf/ft)
    1/4 1 21.0 (120) 0.15 ( 16 000) 0.087 ( 235) 3.7 ( 255)
    2 15.8 ( 90) 0.12 ( 13 000) 0.063 ( 170) 3.7 ( 255)
    3 15.8 ( 90) 0.10 ( 10 500) 0.063 ( 170) 3.7 ( 255)
    4 14.5 ( 83) 0.08 ( 8 800) 0.057 ( 155) 3.7 ( 255)
    11/32 1 22.8 (130) 0.35 ( 37 500) 0.137 ( 370) 5.1 ( 350)
    2 16.6 ( 95) 0.30 ( 31 500) 0.100 ( 270) 5.1 ( 350)
    3 16.6 ( 95) 0.24 ( 25 000) 0.100 ( 270) 5.1 ( 350)
    4 15.6 ( 89) 0.20 ( 21 000) 0.093 ( 250) 5.1 ( 350)
    3/8 1 22.8 (130) 0.50 ( 53 500) 0.183 ( 495) 5.8 ( 395)
    2 17.0 ( 97) 0.42 ( 44 500) 0.133 ( 360) 5.8 ( 395)
    3 17.0 ( 97) 0.33 ( 35 500) 0.133 ( 360) 5.8 ( 395)
    4 15.8 ( 90) 0.28 ( 29 500) 0.124 ( 335) 5.8 ( 395)
    15/32 1 33.3 (190) 1.22 (130 000) 0.313 ( 845) 7.7 ( 525)
    2 24.5 (140) 1.04 (110 000) 0.228 ( 615) 7.7 ( 525)
    3 24.5 (140) 0.82 ( 87 000) 0.228 ( 615) 7.7 ( 525)
    4 22.8 (130) 0.68 ( 72 500) 0.211 ( 570) 7.7 ( 525)
    1/2 1 34.1 (195) 1.41 (150 000) 0.347 ( 935) 8.3 ( 570)
    2 25.4 (145) 1.18 (125 000) 0.252 ( 680) 8.3 ( 570)
    3 25.4 (145) 0.94 (100 000) 0.252 ( 680) 8.3 ( 570)
    4 23.6 (135) 0.80 ( 84 500) 0.234 ( 630) 8.3 ( 570)
    19/32 1 43.8 (250) 2.17 (230 000) 0.463 (1250) 10.1 ( 695)
    2 32.4 (185) 1.79 (190 000) 0.335 ( 905) 10.1 ( 695)
    3 32.4 (185) 1.41 (150 000) 0.335 ( 905) 10.1 ( 695)
    4 29.8 (170) 1.18 (125 000) 0.311 ( 840) 10.1 ( 695)
    5/8 1 43.8 (250) 2.40 (255 000) 0.500 (1350) 10.8 ( 740)
    2 32.4 (185) 2.02 (215 000) 0.361 ( 975) 10.8 ( 740)
    3 32.4 (185) 1.60 (170 000) 0.361 ( 975) 10.8 ( 740)
    4 29.8 (170) 1.32 (140 000) 0.335 ( 905) 10.8 ( 740)
    23/32 1 44.7 (255) 3.34 (355 000) 0.575 (1550) 12.2 ( 835)
    2 33.3 (190) 2.78 (295 000) 0.408 (1100) 12.2 ( 835)
    3 33.3 (190) 2.21 (235 000) 0.408 (1100) 12.2 ( 835)
    4 30.6 (175) 1.84 (195 000) 0.389 (1050) 12.2 ( 835)
    3/4 1 45.5 (260) 3.67 (390 000) 0.612 (1650) 12.6 ( 860)
    2 33.3 (190) 3.06 (325 000) 0.445 (1200) 12.6 ( 860)
    3 33.3 (190) 2.45 (260 000) 0.445 (1200) 12.6 ( 860)
    4 30.6 (175) 2.02 (215 000) 0.408 (1100) 12.6 ( 860)
    7/8 1 46.4 (265) 5.18 (550 000) 0.760 (2050) 14.6 (1000)
    2 34.1 (195) 4.33 (460 000) 0.556 (1500) 14.6 (1000)
    3 34.1 (195) 3.44 (365 000) 0.556 (1500) 14.6 (1000)
    4 32.4 (185) 2.87 (305 000) 0.500 (1350) 14.6 (1000)
    1 1 65.7 (375) 7.91 (840 000) 0.982 (2650) 16.8 (1150)
    2 48.2 (275) 6.59 (700 000) 0.704 (1900) 16.8 (1150)
    3 48.2 (275) 5.27 (560 000) 0.704 (1900) 16.8 (1150)
    4 44.7 (255) 4.38 (465 000) 0.649 (1750) 16.8 (1150)
    1-1/8 1 66.5 (380) 10.36 (1 100 000) 1.205 (3250) 18.3 (1250)
    2 49.0 (280) 8.52 (905 000) 0.871 (2350) 18.3 (1250)
    3 49.0 (280) 6.83 (725 000) 0.871 (2350) 18.3 (1250)
    4 45.5 (260) 5.70 (605 000) 0.816 (2200) 18.3 (1250)
    36
    Bending strength — A minimum of ten tests (specimens taken from ten different panels) shall
    be tested for bending strength both along and across the major panel axis according to the
    procedures of Section 6.2.3. At least 95% of the specimens tested along the major axis
    direction shall meet the value given in Table 9 for the Performance Category tested.
    Planar shear strength — A minimum of ten tests (specimens taken from ten different panels)
    shall be tested for planar shear strength along the major panel axis according to the procedures
    of Section 6.2.4. At least 95% of the tests shall meet the planar shear strength value along the
    major axis given in Table 9 for the Performance Category tested.
    Shear-through-the-thickness strength — A minimum of ten tests (specimens taken from ten
    different panels) shall be tested for shear strength through the thickness according to the
    procedures of Section 6.2.5. At least 95% of tests shall meet the shear-through-the-thickness
    strength value given in Table 9 for the Performance Category tested.
    5.8.7.3 Mill specification
    Upon conformance with the requirements of Section 5.8.7.2, a manufacturing specification
    unique to the product and mill shall be written. This specification shall be used for quality
    assurance purposes by the manufacturer and the qualified testing agency defined in
    Section 7.2. The manufacturing specification shall define veneer species and panel
    construction and shall include the following reference values:
    Thickness — The reference value shall be the average panel thickness less 1.932 standard
    deviations (the 95% lower tolerance limit at 75% confidence) for twenty panels tested under
    Section 5.8.7.2.
    Mechanical Properties
    Bending stiffness — The reference values for each panel direction shall be the lower value of
    a 90% confidence interval (see ASTM D 2915) established on the mean for each panel
    direction.
    Bending strength — The reference values for each panel direction shall be the minimum
    observed value, or the sample mean less 1.8 times the sample standard deviation, whichever is
    the higher value for each panel direction.
    Planar shear strength — The reference value shall be the minimum observed value, or the
    sample mean less 1.8 times the sample standard deviation whichever is the higher value
    Shear-through-the-thickness strength — The reference value shall be the minimum observed
    value, or the sample mean less 1.8 times the sample standard deviation, whichever is the
    higher value.
    As an alternative to the mechanical properties, the performance tests of Section 5.8.7.2 may
    also be used for quality assurance purposes.
    5.9 Scarf and finger jointed panels
    Neither panels with N faces, nor the faces of such panels, unless longer than 3 m (10 ft), shall
    be scarf or finger jointed unless otherwise agreed to by buyer and seller. Panels of other
    grades shall be permitted to be scarf or finger jointed unless otherwise agreed to by buyer and
    seller, and panels longer than 3.7 m (12 ft) are necessarily scarf or finger-jointed. Plain scarfed
    joints and the scarfed portion of finger-joints shall not have a slope greater than 1 to 8. All plies
    37
    with grain perpendicular to the finger joint shall be included in the scarfed portions of the joint,
    except that such plies shall be permitted to include up to 0.8 mm (1/32 in) of vertical shoulder in
    the scarf (see Figure 1). Joints shall be bonded with a moisture resistant adhesive and shall
    meet the test requirements set forth in Sections 5.9.1, 5.9.2, and 5.9.3 as applicable. In
    addition, the adhesive shall not show creep or flow characteristics greater than unjointed wood
    when subject to load under any conditions of temperature and moisture.
    Figure 1. Finger joints – Location of scarfed portion of joints.
    5.9.1 Strength requirements for scarf and finger jointed panels
    If the average ultimate stress of the three test specimens of any one panel is less than
    27.6 MPa (4000 psi) for panels of Group 1 species, or less than 19.3 MPa (2800 psi) for panels
    of Group 2 or Group 3 species, or less than 16.5 MPa (2400 psi) for panels of Group 4 species,
    or less than 13.8 MPa (2000 psi) for panels of Group 5 species, when tested in accordance with
    Section 6.1.5.1, then that panel shall fail. The jointed panels represented by a sampling of ten
    panels shall be acceptable if not more than one of the panels fails and the average ultimate
    stress of the failing panel is at least 80% of that specified for the applicable species group. If
    the average ultimate stress of the failing panel is at least 75% of that specified for the applicable
    species group, another series of ten panels shall be tested. If none of the panels in this series
    fails, the jointed panels shall be accepted; otherwise they shall be rejected.
    38
    5.9.2 Scarf joint bond performance for Exposure 1 and Exterior plywood
    Panels shall be tested in accordance with Section 6.1.5.2. The material represented by the
    sampling shall be evaluated in accordance with Sections 5.7.1, and 5.7.2, as applicable.
    5.9.3 Finger joint bond performance for Exposure 1 and Exterior plywood
    Panels shall be tested in accordance with Section 6.1.5.3. The joints shall meet all of the
    following minimum conditions:
    (a) The average wood failure rating of all specimens from each panel when tested in
    accordance with Section 6.1.5.3 shall be not less than 85%.
    (b) No single specimen from a panel (average of face and back bond lines) shall rate
    less than 60% wood failure.
    (c) No single face or back bond line in any specimen shall rate less than 30% wood
    failure.
    5.10 Dimensional tolerances and squareness of panels
    Panel measurements shall be based on a moisture content of 9%.
    5.10.1 Size tolerances
    A length and a width measurement shall be made at a location 50 to 75 mm (2 to 3 in) from the
    panel edge. A tolerance of plus zero (0) mm, minus 1.6 mm (1/16 in) shall be allowed on the
    manufacturer’s stated length and/or width.
    ADVISORY NOTE: For tongue and grooved and ship-lapped panels, the width and squareness
    measurements should be made on the net panel face.
    5.10.2 Performance Category and thickness tolerances
    Panel thickness shall be measured with a micrometer having 19.1 mm (3/4 in) (minus 0, plus
    1.3 mm [0.050 in]) diameter anvils. Measurements shall be taken at an applied anvil pressure of
    not less than 34 kPa (5 psi) or more than 69 kPa (10 psi). The location of the measurements
    shall be representative of panel thickness mid-length,+/- 50 mm (2 in) along each edge of the
    panel and the average of the four measurements shall be taken as the thickness of that panel.
    If a measurement point contains a permissible grade characteristic that affects panel thickness,
    then the measurement point shall be shifted from that point.
    The panel thickness shall conform to Table 10.
    39
    TABLE 10. PLYWOOD THICKNESS REQUIREMENTS
    Thickness Requirements for
    Unsanded, Touch Sanded and
    Overlaid Grades1
    Thickness Requirements for
    Sanded Grades2
    PERFORMANCE
    CATEGORY3
    Minimum
    Thickness, mm
    (in)
    Maximum
    Thickness, mm
    (in)
    Minimum
    Thickness, mm
    (in)
    Maximum
    Thickness, mm
    (in)
    1/4 PERF CAT 5.56 (0.219) 7.14 (0.281) 5.95 (0.234) 6.75 (0.266)
    11/32 PERF CAT 7.94 (0.313) 9.53 (0.375) 8.33 (0.328) 9.13 (0.359)
    3/8 PERF CAT 8.73 (0.344) 10.32 (0.406) 9.13 (0.359) 9.92 (0.391)
    7/16 PERF CAT 10.32 (0.406) 11.91 (0.469) 10.72 (0.422) 11.51 (0.453)
    15/32 PERF CAT 11.11 (0.438) 12.70 (0.500) 11.51 (0.453) 12.30 (0.484)
    1/2 PERF CAT 11.91 (0.469) 13.49 (0.531) 12.30 (0.484) 13.10 (0.516)
    9/16 PERF CAT 13.49 (0.531) 15.08 (0.594) 13.89 (0.547) 14.68 (0.578)
    19/32 PERF CAT 14.29 (0.563) 15.88 (0.625) 14.68 (0.578) 15.48 (0.609)
    5/8 PERF CAT 15.08 (0.594) 16.67 (0.656) 15.48 (0.609) 16.27 (0.641)
    23/32 PERF CAT 17.46 (0.688) 19.05 (0.750) 17.86 (0.703) 18.65 (0.734)
    3/4 PERF CAT 18.26 (0.719) 19.84 (0.781) 18.65 (0.734) 19.45 (0.766)
    13/16 PERF CAT 19.84 (0.781) 21.43 (0.844) 20.02 (0.788) 21.26 (0.837)
    7/8 PERF CAT 21.11 (0.831) 23.34 (0.916) 21.56 (0.849) 22.89 (0.901)
    1 PERF CAT 24.13 (0.950) 26.67 (1.050) 24.64 (0.970) 26.16 (1.030)
    1-1/8 PERF CAT 27.15 (1.069) 30.00 (1.181) 27.72 (1.091) 29.43 (1.159)
    1-1/4 PERF CAT 30.16 (1.188) 33.34 (1.313) 30.80 (1.213) 32.70 (1.288) 1Thickness requirements for unsanded, touch sanded, and overlaid panels are based on a tolerance of ± 0.8 mm
    (1/32 in) for panels with Performance Categories of 13/16 and less and ± 5% for panels with Performance Categories
    greater than13/16 unless a closer tolerance is determined through qualification testing.
    2Thickness requirements for sanded panels is based on a tolerance of ± 0.4 mm (1/64 in) for panels with
    Performance Categories of 3/4 and less and ± 3.0% for panels with Performance Categories greater than 3/4 unless
    a closer tolerance is determined through qualification testing.
    3 For labeling purposes, abbreviation of “Performance Category” by PERF CAT, CAT or Category is permitted.
    Performance Categories for other panel thicknesses are permitted.
    5.10.3 Squareness and straightness
    Squareness and straightness – Panels shall be square within 1.3 mm per lineal meter of the
    longest edge (1/64 in per lineal foot) measured along the diagonals. All panels shall be
    manufactured so that a straight line drawn from one corner to the adjacent corner is within
    1.6 mm (1/16 in) of the panel edge.
    5.11 Moisture content
    Moisture content of panels at time of shipment shall not exceed 18% when tested in accordance
    with Section 6.1.4.
    5.12 Loading or packing
    The plywood shall be securely loaded or packaged to ensure delivery to destination in a clean
    and serviceable condition.
18. SPECIMEN PREPARATION AND TESTING
    6.1 Bond classification
    6.1.1 General
    The tests set forth in this section shall be used to determine the adhesive bond quality of
    plywood produced under this Standard.
    40
    6.1.2 Specimen preparation (see appendix B for sampling for reinspection)
    Testing shall follow the principles of ASTM D906 and procedures herein. One test piece shall be
    cut from each panel selected. Unless otherwise specified by the qualified testing agency, 10
    test specimens shall be cut as described in Section 6.1.3.1 for panels bonded with moistureresistant adhesive. Of the 10 specimens cut from each test piece for panels bonded with
    moisture resistant adhesive, 5 shall be for the vacuum-pressure test and 5 shall be for the boil
    test. In addition, from each panel selected, a specimen 140 mm by 203 mm (5-1/2 x 8 in) shall
    be cut and tested as described in Section 6.1.3.4.
    6.1.3 Tests for Exposure 1 and Exterior plywood
    6.1.3.1 Preparation of test specimens
    Test specimens taken as described in Section 6.1.2 shall be cut 82.6 mm long by 25.4 mm wide
    (3-1/4 in x 1 in), and kerfed one-third of the length of the specimen from each end, as illustrated
    in Figure 2 to provide a 25.4 mm (1 in) square test area in the center. Specimens shall be
    oriented so that the grain direction of the ply under test runs at a 90° angle to the length of the
    specimen. Kerfing shall extend two-thirds of the way through the ply under test, and shall not
    penetrate the next bond line. For overlaid plywood, the additional 10 specimens for testing of
    bond between veneers shall be cut as described in this section for Exterior specimens except
    that they shall be cut 25.4 mm (1 in) wide and 76.2 mm (3 in) long, and kerfed just through the
    overlay 25.4 mm (1 in) from the end, on each overlay face.
    Figure 2. Shear test specimens.
    If the number of plies exceeds three, the cuts shall be made so as to test any two of the joints,
    but the additional plies need not be stripped except as demanded by the limitations of the width
    of the retaining jaws on the testing device. When required to accommodate thicker plywood,
    special jaws shall be constructed. If the number of plies exceeds three, the choice of joints to
    be tested shall be left to the discretion of the qualified inspection and testing agency, but at least
    one-half of the tests shall include the innermost joints.
    6.1.3.2 Vacuum-pressure test
    The test specimen shall be placed in a pressure vessel and submerged in cold tap water. A
    vacuum of 83.5 kPa to 98.5 kPa or 24.7 inches to 29.0 inches of mercury shall be drawn and
    maintained for 30 minutes, followed immediately with application of 450 kPa to 480 kPa (65 psi
    to 70 psi) of pressure for 30 minutes duration. Specimens shall then be removed from the
    vessel and tested
    41
    while wet by tension loading to failure in a shear testing machine operated at a maximum head
    travel of 762 mm (30 in) per minute. The jaws of the machine shall securely grip the specimens
    so there is no slippage. The percentage of wood failure of the specimens shall be determined in
    a dry condition in accordance with ASTM D5266 and evaluated as described in Sections 5.7.1
    and 5.7.2.
    The bond between veneers in overlaid plywood shall be tested in an identical manner and
    evaluated as described in Section 5.7.2. Specimens for testing the bond between the overlay
    and the base panel shall be subjected to the same test cycle just described. The bond between
    the overlay and the base panel shall be tested by inserting a sharp, thin blade of adequate
    stiffness into the corner of the 25.4 mm (1 in) test area at the overlay-veneer interface, taking
    care not to cut into the overlay, and attempting to peel the overlay off. Reinsertion of the blade
    several times shall be permitted if necessary, to remove the overlay from the 6.5 cm2
    (1 in2
    )
    area. The percentage of wood and/or fiber failure shall then be estimated with specimens in a
    dry condition in accordance with ASTM D5266 and evaluated as described in Section 5.7.2.
    The value for each specimen shall be the average of the test areas on each face.
    6.1.3.3 Boiling test
    Test specimens shall be boiled in water for 4 hours and then dried for 20 hours at a temperature
    of 63 ± 3° C (145 ± 5° F) with sufficient air circulation to lower moisture content of the
    specimens to a maximum of 8%. The specimens shall be boiled again for a period of 4 hours,
    cooled in water, and tested while wet by tension loading to failure in a shear testing machine
    operated at a maximum head travel of 762 mm (30 in) per minute. Jaws of the machine shall
    securely grip the specimens so there is no slippage. The percentage of wood failure of the
    specimens shall be determined with specimens in a dry condition in accordance with ASTM
    D5266 and evaluated as described in Sections 5.7.1 and 5.7.2.
    The bond between veneers in overlaid plywood shall be tested in an identical manner and
    evaluated as described in Section 5.7.2. Specimens to test the bond between the overlay and
    the base panels shall be subjected to the same test cycle described in the previous paragraph.
    The bond between the overlay and the base panel shall be tested by inserting a sharp, thin
    blade of adequate stiffness into the corner of the 25.4 mm (1 in) test area at the overlay-veneer
    interface, taking care not to cut into the overlay, and attempting to peel the overlay off.
    Reinsertion of the blade several times shall be permitted if necessary, to remove the overlay
    from the 6.5 cm2
    (1 in2
    ) area. The percentage of wood and/or fiber failure shall then be
    estimated with specimens in a dry condition in accordance with ASTM D5266 and evaluated as
    described in Section 5.7.2. The value for each specimen shall be the average of the test areas
    on each face.
    6.1.3.4 Heat performance test
    A specimen cut as described in Section 6.1.2 shall be placed on a stand as illustrated in
    Figure 3. A specimen shall then be subjected to an 800° C to 900° C (1472° F to 1652° F)
    flame from a Bunsen-type burner for a period of 10 minutes, or until a brown charred area
    appears on the back side, whichever occurs first. The burner shall be equipped with a wing top
    to envelop the entire width of the specimen in flame. The top of the burner shall be 25.4 mm (1
    in) from the specimen face and the flame 38.1 mm (1-1/2 in) high. The flame shall impinge on
    the face of the specimen 50.8 mm (2 in) from the bottom end. After the test, the sample shall be
    removed from the stand and the bond lines examined for delamination by separating the
    charred plies with a sharp, chisel-like instrument. Specimens shall be evaluated in accordance
    with the requirements of Section 5.7.2.1.
    42
    Figure 3. Apparatus for heat durability test.
    6.1.4 Test for determination of moisture content (oven-drying method)
    The moisture content of the plywood shall be determined as follows: A small test specimen
    shall be cut from each sample panel; the test specimen shall measure not less than 58 cm2
    (9 in2
    ) in area and shall weigh not less than 20 grams (approximately 3/4 ounce). All loose
    splinters shall be removed from the specimen. The specimen shall be immediately weighed on
    a scale that is accurate to ±0.5%, and the weight shall be recorded as the “original” weight. The
    specimen shall then be dried in an oven at 100° C to 105° C (212° F to 221° F) until constant
    weight is attained. After drying, the specimen shall be reweighed immediately, and this weight
    shall be recorded as the “oven-dry” weight. The moisture content shall be calculated as follows:
    100 Moisture content (%) (Oven dry weight)
    (Original weight) – (Oven dry weight)
    × =
    6.1.5 Scarf and finger-joint tests
    6.1.5.1 Scarf and finger-joint strength
    Three test specimens shall be cut at random along each joint from each panel selected. Type,
    grade and species of the panels shall be recorded. The specimens shall be cut so as to include
    the joint and shall be prepared as illustrated in Figure 4.
    43
    Figure 4. Tension specimen for scarf jointed panels.
    Insofar as possible, the joint test area shall contain no localized natural characteristics permitted
    within the grade. At the joint, the maximum thickness and width of plies parallel with the load
    shall be recorded. Each specimen shall then be placed in the tension grips of a testing machine
    and loaded continuously at a rate of cross-head travel of from 0.8 mm to 1.0 mm (0.030 in to
    0.040 in) per minute until failure, and the ultimate load shall be recorded. The ultimate stress in
    MPa (psi) shall be computed using the ultimate load and area of those plies whose grain is
    parallel with direction of load. Moisture content of the specimens at the time of testing shall not
    exceed 16%.
    6.1.5.2 Scarf joint bond performance of Exterior and Exposure 1 plywood
    Ten test specimens shall be cut at random along each joint from each panel selected according
    to Section 6.1.2. The specimens shall be prepared following the general procedure described in
    Section 6.1.3.1 and shall be cut so that the joint runs through the test specimens as shown in
    Figure 5.
    Figure 5. Specimen preparation.
    Five specimens shall be subjected to the vacuum-pressure test described in Section 6.1.3.2,
    and five to the boiling test of Section 6.1.3.3. The panels shall be evaluated as described in
    Sections 5.7.1 and 5.7.2.
    6.1.5.3 Finger-joint bond performance of Exterior and Exposure 1
    Ten specimens shall be cut at random along the finger joint from each panel selected according
    to Section 6.1.2. These specimens shall be cut so as to include the joint and shall be prepared
    as illustrated in Figure 6.
    44
    Figure 6. Cleavage test, typical test specimen.
    Five of the specimens shall be subjected to the vacuum-pressure test of Section 6.1.3.2 and five
    to the boiling test of Section 6.1.3.3.
    Upon completion of the applicable moisture cycle(s), a wedge or chisel (see Figure 7) shall be
    inserted in locations shown in Figure 6 in such a manner as to pry apart the scarfed portions of
    the joint without directly contacting the bonded area. Test specimens shall be dried and percent
    wood failure in the test area estimated and applied separately for both the boil and vacuumpressure treatments. The panels shall be evaluated as described in Section 5.9.3.
    Figure 7. Wedge or chisel used for cleavage test.
    6.2 Structural performance
    6.2.1 Tests for performance under concentrated static and impact loads
    6.2.1.1 General
    The general provisions of ASTM E 661 shall be followed except as modified in these sections.
    The test span shall be 19.2 inch for the span rating of 20.
    The dry test condition shall be within +/- 3% of the as-shipped moisture content. The wet test
    condition shall be exposure to three days of continuous wetting, then tested wet. The wet/redry
    condition shall be exposure to three days of continuous wetting, followed by testing within 3% of
    the as-shipped moisture content.
    6.2.1.2 Specimen preparation
    Test specimens shall be prepared as specified in ASTM E 661. The number of specimens
    required is given in Section 5.8.6.3. Specimens shall also be moisture cycled as required.
    45
    6.2.1.3 Test procedure
    Concentrated static — Procedures of ASTM E 661 shall be followed, except the test frame
    shall be constructed of lumber with nails or of steel using fasteners which simulate nails. The
    loading rate shall be 445 N (100 lbf) per 30 seconds to yield failure within 5 minutes if a handpumped hydraulic loading system is used.
    Concentrated impact — Procedures of ASTM E 661 Method A shall be followed, except:
    (a) The test frame shall be constructed of lumber with nails or of steel using
    fasteners which simulate nails.
    (b) For span ratings greater than 24 o.c., the shot bag shall weigh 27 kg (60
    pounds).
    The width of individual pieces in assembling a test shall be 610 mm (24 in) or greater for span
    ratings up to 24 o.c., and 1220 mm (48 in) for greater span ratings.
    6.2.2 Test for performance under uniform loads
    6.2.2.1 General
    This method shall determine the performance of structural-use panels under uniform loads such
    as snow, wind and occupancy loads. The uniform load is applied by atmospheric pressure as a
    vacuum is drawn under the test specimen, which is mounted on fully-supported framing
    members in a vacuum chamber.
    6.2.2.2 Equipment
    Vacuum chamber — The vacuum chamber (see Figure 8) shall consist of a sealed box with
    the panel to be tested forming the top. A 0.15 mm (6 mil or 0.006 in) polyethylene sheet or
    equivalent, the perimeter of which is attached securely with tape, shall seal the top surface of
    the vacuum chamber. The chamber shall be strong and rigid to resist the applied load without
    failure or excessive deformation. A vacuum pump shall be used to reduce the air pressure
    under the specimen. The load shall be measured with absolute pressure gages for electronic
    data readout, but manometers or vacuum gages shall also be permitted.
    46
    Figure 8. Vacuum chamber test equipment.
    Joist supports — The framing members shall be spaced at the intended span rating, except
    that 20 span rating shall have framing spaced 19.2 inch. Framing shall be supported so as to
    resist deflection or rotation under applied load.
    Deflection gages — The deflection gages shall be mounted to rigid tripods whose legs rest
    above the joists. Deflection shall be measured to the nearest 0.03 mm (0.001 in).
    6.2.2.3 Specimen preparation
    Samples shall be selected that are representative of the product being tested.
    Length — The specimen length perpendicular to the framing member shall be equal to twice
    the center-to-center spacing.
    Width — The specimen width shall be at least 597 mm (23-1/2 in).
    Thickness — The specimen thickness shall be measured after conditioning and recorded.
    6.2.2.4 Test procedure
    After conditioning, the specimen to be tested shall be mounted on the framing members in the
    vacuum chamber in accordance with the anticipated joist spacing and the recommended nail
    size and spacing. The top of the vacuum chamber shall then be sealed with the polyethylene
    sheet, and the tripod holding the deflection gages set in its proper position with the gages
    positioned to read deflection at the point of maximum deflection2 of the two outer spans
    (Figure 9).
    2 The point of maximum deflection for a uniformly loaded two-span system shall occur at 0.4215 (S)
    measured from the centerline of the outer joist, where S equals the center-to-center joist spacing.
    47
    Figure 9. Uniform-load test specimens.
    The panel shall be loaded at a uniform rate of 2.4 kPa (50 lbf/ft2
    ) per minute and deflections
    recorded at 1.2 kPa (25 lbf/ft2
    ) increments until maximum load is achieved or until the desired
    proof load is achieved, as required. Deflection data shall be required only in sufficient numbers
    to develop the straight line portion of the load-deflection curve. In no case shall the number of
    data points be less than six. Deflection at a given load shall be determined by translating the
    slope to pass through the origin, thereby correcting for any settling of the system.
    6.2.3 Test for panel bending
    6.2.3.1 General
    This test procedure shall provide the basic data regarding full panel bending strength and
    stiffness. The general provisions of ASTM D 3043 Method C shall be followed.
    6.2.3.2 Specimen preparation
    Specimens shall be prepared according to ASTM D 3043 Method C.
    6.2.3.3 Test procedure
    The procedures of ASTM D 3043 Method C shall be followed except specimens shall be tested
    for stiffness both along and across the major panel axis, and the maximum bending moment
    shall be taken as required.
    6.2.4 Test for planar shear strength
    6.2.4.1 General
    This test procedure shall determine the shear strength of plywood panels associated with shear
    distortion of the planes parallel to the edge planes of the panel. The general provisions of
    ASTM D 2718 shall be followed.
    48
    6.2.4.2 Specimen preparation
    Specimens shall be prepared in accordance with ASTM D 2718. Specimens shall be prepared
    to evaluate planar shear with the face grain direction parallel to the long dimension
    6.2.4.3 Test procedure
    The procedures of ASTM D 2718 (Method A or Method B) shall be followed. Lumber side
    plates may be used in lieu of steel plates in Method A. The planar shear strength shall be
    measured parallel to the face grain direction.
    6.2.5 Test for shear-through-the-thickness strength
    6.2.5.1 General
    This test procedure shall determine the shear strength when loads are developed along
    opposite edges of panels. The general provisions of ASTM D 2719 Method C shall be followed.
    6.2.5.2 Specimen preparation
    Specimens shall be prepared in accordance with ASTM D 2719 Method C – Two Rail Test.
    6.2.5.3 Test procedure
    The procedures of ASTM D 2719 Method C shall be followed. The shear-through-the-thickness
    strength shall be measured and reported as a capacity, Fvtv.
19. GRADEMARKING AND CERTIFICATION
    7.1 Certification
    Plywood represented as being in conformance with this Standard shall bear the mark of a
    qualified inspection and testing agency which (1) either inspects the manufacture (with
    adequate sampling, testing of bond line, and examination for quality of all veneers) or (2) has
    tested a random sampling of the finished panels in the shipment being certified for conformance
    with this standard. The mark shall maintain legibility after weather exposure during construction.
    7.2 Qualified inspection and testing agency
    A qualified inspection and testing agency is defined to be one that:
    (a) A qualified inspection agency is defined as one that is accredited to ISO/IEC
    17020, Conformity Assessment – Requirements for the Operation of Various
    Types of Bodies Performing Inspections. An agency accredited to ISO/17065,
    Conformity Assessment-Requirements for Bodies Certifying Processes and
    Services and meets the applicable requirements of ISO/IEC 17020 and has
    inspections included in its certification scheme meets the definition of qualified
    inspection agency.
    (b) A qualified testing agency is defined as one that is accredited to ISO/IEC 17025,
    General Requirements for the Competence of Testing and Calibration
    Laboratories. An agency accredited to ISO/17065, Conformity AssessmentRequirements for Bodies Certifying Processes and Services and meets the
    applicable requirements of ISO/IEC 17025 and has testing included in its
    certification scheme meets the definition of qualified testing agency.
    49
    7.3 Panel marking
    All panels represented as conforming to this Standard shall be identified with marks giving the
    following information:
    (a) Species group number, span rating and class — Unless otherwise provided,
    panels which are produced with face and back veneers of the same species
    group shall be identified as being of that species group. Touch-sanded panels
    without span ratings that are manufactured with face and back plies of different
    species groups shall be identified by the larger numbered species group (i.e.,
    Group 4 is larger numbered than Group 1). Sanded panels with Performance
    Category of 3/8 or less, and Decorative panels of any Performance Category,
    that are manufactured with face and back plies of different species groups shall
    be identified by the face species group number. Sanded panels with
    Performance Category greater than 3/8 that are manufactured with face and
    back plies of different species groups shall be identified by the larger numbered
    species group, except that sanded panels with C or D grade backs shall be
    permitted to be identified by the face species group number if backs are no more
    than one species group larger in number than the face and are 3.2 mm (1/8 inch)
    or thicker before sanding. A class number as provided in Section 5.6.4 shall be
    used in lieu of a species group number to identify concrete form panels and a
    span rating shall be used for grades as provided for in Section 5.8.5.
    (b) Bond Classification — The panel mark shall include the Exterior or Exposure 1
    bond classification. Any further reference to adhesive bond, including those
    which imply premium performance or special warranty by the manufacturer, as
    well as manufacturer’s proprietary designations, shall be separated from the
    grademarks or trademarks of the testing agency by not less than 152 mm (6 in).
    (c) The grade name or the grade of face and back veneers or a mark of a qualified
    inspection and testing agency. If identified by such a mark, the product
    specification shall be available from the qualified inspection and testing agency
    whose mark appears on the panel. MDO and HDO panels with one working face
    shall include “One Working Face” or “1S” within the grade declaration. MDO and
    HDO panels with two working faces may include “Two Working Faces” or “2S”
    within the grade declaration.
    (d) The symbol “PS 1-19” signifying conformance with this Standard.
    (e) The panel fractional Performance Category (see section 5.10.2) and term
    “Performance Category” or abbreviation (i.e., PERF CAT, CAT or Category) shall
    be labeled on the panel. In addition, the thickness in 1000ths of an inch within the
    permitted tolerance for the Performance Category shall be labeled on the panel.
    See Appendix D for a table of recommended Thickness labels.
    (f) The designation “Butt-Jointed Center” for those panels manufactured with butt
    joints in center plies in accordance with Section 5.8.
    7.4 Voiding marks
    Panels originally marked as conforming to this Standard but subsequently rejected as not
    conforming thereto shall have any reference to the Standard obliterated or voided by the
    manufacturer as follows:
    50
    Shop panels shall be plainly marked by means of a 102 mm by 127 mm (4 in x 5 in) minimum
    size mark carrying the legend “Shop-cutting panel — all other agency marks void.” (See
    Section 2.56.)
    Other panels rejected as not conforming shall be plainly identified by a mark placed next to, and
    be no less prominent than the original mark, carrying the legend, “REJECT – All other agency
    marks void”.
    No reference shall be made to this Standard in the certification or grade trademarking of panels
    not conforming to all of the applicable provisions of this Standard.
20. EFFECTIVE DATE
    The effective date of this Standard is December 1, 2019. As of the effective date, reference to
    PS 1-19 shall be permitted in contracts, codes, advertising, invoices, product labels, and the
    like, but no product shall be advertised or represented in any manner which would imply or tend
    to imply approval or endorsement of that product by the National Institute of Standards and
    Technology, the Department of Commerce, or by the Federal Government.
21. STANDING COMMITTEE
    A Standing Committee for PS 1-19 will be appointed to be responsible for interpretation and for
    consideration of future proposals for amendments and revisions to the Standard. The names of
    the members are available from the Committee’s Secretariat: Standards Coordination and
    Conformity Group, Standards Services Division, National Institute of Standards and Technology,
    100 Bureau Drive, MS 2100, Gaithersburg, MD 20899-2100. Comments regarding the
    Standard and suggestions for its amendment or revision may also be sent to this address or
    contact NIST at http://ts.nist.gov/ssd.
    Issues regarding interpretation or implementation of the Standard and third-party quality
    assurance policies and procedures shall be considered by a Standard Implementation Review
    Subcommittee as appointed by the Standing Committee. A request to consider such issues
    shall be made in writing to the Secretariat of the Standing Committee (NIST), who will bring it to
    the attention of the Standing Committee. Formal operating procedures developed for the
    Subcommittee shall be subject to approval by NIST. Any recommended actions by the
    Subcommittee will be reported to the Standing Committee for their consideration and action.
    51
    Appendix A. Species Grouping (mandatory)
    A1 General
    Product Standard PS 1 has included provisions for species grouping since the inception of PS 1
    in 1966. Prior to PS 1-66, U.S. plywood was manufactured in accordance with three regional
    plywood standards, Commercial Standard CS45-60 for Douglas-fir Plywood, Commercial
    Standard CS 122-60 for Western Softwood Plywood and Commercial Standard CS 269-63 for
    Southern Pine Plywood. Grouping of wood species on the basis of similar mechanical
    properties in order to provide needed simplification in product manufacture, design and
    specification became possible with the advent of ASTM D 2555, Methods for Establishing Clear
    Wood Strength Values.
    A2 Grouping in practice
    Under the provisions of PS 1, it is possible to manufacture span rated plywood Sheathing and
    Single-Floor on the basis of the species group and plywood construction. Similarly, the plywood
    group rating or plywood classification of non-span rated plywood may be determined by the
    species group and plywood construction. PS 1-83 introduced the provisions of determining
    span ratings on the basis of performance testing. PS 1-95 included a performance-based
    method for evaluating new species not listed in Table 1, made desirable because of the
    changing available timber resource for plywood production.
    A3 Species grouping
    Wood species in Table 1 are grouped on the basis of mechanical properties. Because bending
    stiffness and bending strength are the most important properties for many plywood uses,
    species groups were initially set up first on the basis of bending stiffness and second on the
    basis of bending strength. Past practice of the PS 1 Standing Committee has been to add new
    species to the highest existing group so long as none of the existing group properties
    assignments provided in Table A1 are reduced by the addition.
    A3.1 Assignment of a species group shall be as follows:
    (a) Obtain average and standard deviation data of the five important mechanical
    properties of clear, straight-grained solid wood of all species in each group in the
    green and dry condition. The five properties are bending modulus of elasticity
    (MOE), bending modulus of rupture, compression parallel to grain, shear parallel
    to grain and compression perpendicular to grain. Property data for North
    American woods must be included in ASTM D 2555 or must be developed by the
    U.S. Forest Service or by a recognized Canadian government Laboratory. In
    addition, new data must be obtained using recognized statistical sampling of the
    entire growth range of the species. Foreign species are classified using data
    from the government laboratory in the respective country. Table A2 provides the
    source of data used to classify non-North American species listed in PS 1. For
    each of the five properties, the limiting property value that can be assigned to any
    group that includes that species is determined at the dry (12% for MOE, 15% for
    all other properties) and green moisture content.
    (b) The maximum assignable MOE value is either the species average increased by
    10% if volume data is available in ASTM D2555 or the species average if no
    volume data exists or if it is a foreign species.
    (c) The strength properties are calculated in one of the following three methods:
    Method A species in ASTM D 2555
    52
    Max. Assignable = (species average/variability index) – 1.18 x species standard
    deviation
    Method B species in ASTM D 2555
    Max. Assignable = species average – 1.48 x species standard deviation
    Domestic species with no volume data and foreign species
    Max. Assignable = species average – 1.645 x species standard deviation
    The maximum assignable property must meet or exceed all property values listed
    in Table A1 for the species group in order to be assigned that group.
    (d) Assignment of a species group to Table 1 shall be approved by the Standing
    Committee. (See Section 5.2.)
    TABLE A1. CLEAR WOOD PROPERTY ASSIGNMENTS
    Species
    Group
    MOE
    (million psi)
    Strength Property (psi)
    Bending Comp Par Shear Comp Perp
    Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry
    1 1.483 1.857 5300 8064 2425 4123 665 855 193 354
    2 1.249 1.588 3662 6297 1833 3163 532 692 124 221
    3 1.047 1.310 3681 5985 1548 2662 524 652 123 212
    4 0.924 1.146 3483 5389 1570 2630 476 633 97 152
    5 0.748 1.100 2843 4345 1190 2187 387 542 73 132
    53
    TABLE A2. SOURCE OF DATA USED TO CLASSIFY FOREIGN SPECIES IN PLYWOOD
    PRODUCT STANDARD PS 1
    Common Name or
    Trade Group
    Scientific Name Source of Data
    Group 1
    Apitong Dipterocarpus spp. FPL 125
    FPL 2242 (bearing only)
    Kapur Dryobalanops aromatica
    D. lanceolata
    D. oblongifolia
    Malayan Forest Service Trade Leaflet #34
    FPL 125
    Malayan Forest Service Trade Leaflet #34
    Keruing Dipterocarpus spp.
    D. baudii
    D. caudiferus
    D. cornutus
    D. crinitus
    D. lowii
    FPL 2242
    Malayan Forest Service Trade Leaflet #34
    FPL 2242
    Malayan Forest Service Trade Leaflet #34
    Malayan Forest Service Trade Leaflet #34
    Malayan Forest Service Trade Leaflet #34
    Caribbean Pine Pinus caribaea FPL 125
    Ocote Pine Pinus oocarpa FPL 125
    Group 2
    Red Lauan Shorea negrosensis FPL 125
    FPL 2242 (bearing only)
    Tangile Shorea polysperma FPL 125
    FPL 2242 (bearing only)
    White Lauan Pentacme contorta FPL 125
    FPL 2242 (bearing only)
    Almon Shorea almon FPL 125
    FPL 2242 (bearing only)
    Bagtikan Parashorea plicata FPL 125
    FPL 2242 (bearing only)
    Mersawa Anisoptera laevis
    A. marginata
    Malayan Forest Service Trade Leaflet #34
    Malayan Forest Service Trade Leaflet #34
    Mayapis Shorea squamata FPL 125
    Meranti Parashorea lucida
    Shorea acuminata
    S. singkawang
    S. curtisii
    S. dasyphylla
    Malayan Forest Service Trade Leaflet #5
    Malayan Forest Service Trade Leaflet #34
    Malayan Forest Service Trade Leaflet #34
    Malayan Forest Service Trade Leaflet #34
    FPL 125
    S. hemslevana Malayan Forest Service Trade Leaflet #34
    S. leprosula
    S. macroptera
    Malayan Forest Service Trade Leaflet #34
    Malayan Forest Service Trade Leaflet #34
    S. pauciflora
    S. platyclados
    Malayan Forest Service Trade Leaflet #34
    Malayan Forest Service Trade Leaflet #34
    S. rugosa Malayan Forest Service Trade Leaflet #34
    Group 4
    Cativo Prioria copaifera FPL 125
    Yale Bulletin #98 Tropical Woods (bearing only)
    54
    Appendix B. Reinspection Practices (nonmandatory)
    B1 General
    Based on industry practice, the following information is offered plywood purchasers:
    B2 Request for reinspection
    Any request by the buyer for the reinspection of any item or lot of plywood certified as
    conforming to this Standard shall be directed to the seller. Lacking agreement of the buyer and
    seller as to the settlement of a complaint, the purchase, sale, or shipment of plywood certified
    as conforming to this Standard shall be construed as involving agreement to submit such
    plywood to reinspection by the qualified inspection agency whose grademark was used.
    B3 Responsibility of the buyer
    A request for reinspection shall be made to the seller:
    For panel grade — within 30 days after arrival at the first point of receipt from the mill, if the
    grade of any item, as invoiced, is in doubt;
    For adhesive bond quality of Exterior panels — when delamination is visibly evident;
    For adhesive bond quality of Exposure 1 — within 6 months after arrival at first point of receipt
    from the mill if delamination is visibly evident;
    All plywood of disputed grade shall be kept intact and properly protected from damage,
    deterioration and from direct exposure to moisture which could interfere with a fair reinspection.
    All plywood in question shall be held for a period not to exceed 30 days after the date of request
    for reinspection. Use by the buyer of any or all of the disputed stock within the 30-day period
    shall constitute an acceptance of the used portion.
    B4 Responsibility of the seller
    A request for reinspection shall be promptly acknowledged by the seller following receipt of the
    request.
    B5 Responsibility of the qualified inspection agency conducting the reinspection
    Should either the buyer or the seller wish to have a representative present at the reinspection,
    the agency conducting the reinspection will provide all reasonable accommodation to facilitate
    that request. Any party wishing to witness the reinspection shall inform the agency of that desire
    at the time of the initial request for reinspection, and shall be responsible for any costs they
    incur in order to attend. Costs incurred by the agency performing the reinspection shall be
    assessed as noted in Section B6.
    B6 Cost and assistance
    The expense of reinspection shall be borne by the seller if the item, lot, or shipment in dispute
    fails to pass the reinspection as provided for in Section B7. If the plywood passes the
    reinspection, said expenses shall be borne by the buyer. The buyer shall lend all reasonable
    assistance to facilitate the reinspection.
    B7 Reinspection procedures and settlement
    B7.1 Condition of plywood
    All plywood designated as complying with this Standard shall be subject to reinspection in the
    white (unfinished) only, except that concrete-form material is permitted to have a priming coat of
    a release agent. This requirement does not apply to Exposure 1 or Exterior plywood when
    tested for adhesive bond quality.
    55
    B7.2 Sampling for panel grade, size and thickness reinspections
    At buyer’s or seller’s option, grade, size, and thickness reinspections shall include all panels of
    an item whose conformance to this Standard is in dispute; however, agreement between the
    buyer and seller on a reduced basis for sampling is permitted provided at least 20% or 300
    panels, whichever is smaller and which represents only those items as invoiced which are in
    dispute, are reinspected for conformance. For reduced sampling, the quantity of panels
    selected from each disputed item shall be prorated according to the number of panels included
    in each item as invoiced. Panels found to be below grade or out of tolerance for size and
    thickness shall have improper grademarks obliterated and shall be remarked with appropriate
    designation with a special inspection mark registered by the qualified agency conducting the
    reinspection and applied by that agency’s authorized representative.
    B7.3 Plywood panel grade, size and thickness reinspections
    If reinspection establishes that a disputed item is more than 5% below grade or out of
    dimensional tolerance for the product description as invoiced, that product fails to pass the
    reinspection and the nonconforming panels need not be accepted. If a disputed product is 5%
    or less below grade or out of dimensional tolerance, it shall pass the reinspection and the
    disposition of the nonconforming panels shall be as agreed upon between buyer and seller. In
    addition to the above 5% grade and dimensional tolerance, a 5% tolerance shall apply
    separately to the inner ply gap limitations, including the limitations applicable to the plugged
    crossband and jointed crossband, as set forth in section 5.8.1.
    B7.4 Sampling for adhesive bond quality reinspections
    For test purposes, twenty panels, or 5% of the panels, whichever is less, shall be selected at
    random from the item, lot, or shipment which is in dispute. The number of panels required is
    calculated by applying the “percent panels” to the lot size and converting part panels to whole
    panels by using a rounding procedure where 0.01 to 0.49 parts are considered to be the smaller
    whole number, while 0.50 to 0.99 parts are considered to be the larger whole number. These
    panels shall be selected from locations distributed as widely as practicable throughout the
    material being sampled. When an item, lot, or shipment involves panels with different adhesive
    bond requirements as provided for in 5.7, testing and evaluation shall apply separately to each
    category. Sampling of Exposure 1 plywood or Exterior plywood shall be prorated on the basis
    of ratio of their volume to total volume (i.e., for shipment containing 50% Exterior, 10 Exterior
    panels shall be selected), but in no case shall less than 10 panels of each type or adhesive
    quality be selected. Shipments of Exposure 1 plywood shall be sampled in the same manner as
    Exterior plywood.
    From each of five of the panels selected, a specimen 140 mm by 203 mm (5-1/2 in x 8 in) shall
    be cut and tested as described in Section 6.1.3.4.
    B7.5 Plywood adhesive bond quality reinspections
    Reinspection of the unused panels in the disputed item, lot, or shipment shall be carried out
    following the procedures set forth in Section 6, “Specimen Preparation and Testing,” and
    Section B7.4. If the reinspection tests establish that the adhesive bond quality of the panels
    does not meet the requirements of Section 5.7, as applicable, the item, lot, or shipment shall fail
    to pass the reinspection and is not required to be accepted by the buyer. If the adhesive bond
    quality requirements are met, the item, lot, or shipment shall pass the reinspection and the
    buyer shall accept the item, lot, or shipment as invoiced, except that the buyer is not required to
    accept any delaminated Exterior plywood or overlaid panels.
    56
    Appendix C. General Information and Comments On Current Edition (nonmandatory)
    C1 History of the project
    On October 1, 1965, the American Plywood Association (now APA – The Engineered Wood
    Association) submitted to the National Bureau of Standards (now the National Institute of
    Standards and Technology) a draft of a proposed Commercial Standard on softwood plywood,
    with a request that it be processed as a revision and consolidation of Commercial Standards
    CS 45-60 Douglas Fir Plywood, CS 122-60 Western Softwood Plywood, and CS 259-63
    Southern Pine Plywood. On November 1, 1966, Product Standard PS 1-66 Softwood Plywood,
    Construction and Industrial became effective. It was the first Voluntary Product Standard
    developed under new Department procedures, issued on November 16, 1965, for development
    of Voluntary Product Standards.
    Since 1966, there have been six revisions to the Standard:
    C2.1 PS 1-74 Construction and Industrial Plywood became effective August 1, 1974
    Among other revisions, this version added over 20 species, primarily Southeast Asian
    hardwoods, to Table 1.
    C2.2 PS 1-83 Construction and Industrial Plywood became effective December 30, 1983
    This version added performance-based test methods and criteria for span rated applications.
    C2.3 PS 1-95 Construction and Industrial Plywood became effective September 7, 1995
    This version included the incorporation of a performance-based method for evaluating plywood
    manufactured with species not listed in Table 1, made desirable because of the changing
    available timber resource for plywood production. The revisions included the elimination of
    Structural II panel grades from the Standard because this product had rarely been
    manufactured since it was first introduced in PS 1-66.
    C2.4 PS 1-07 Structural Plywood became effective February 26, 2007
    This version revised several sections of the standard to better represent the production and
    trade specifications for the products. These included a change to the title of the standard,
    elimination of the interior and intermediate bond types, revisions to the overlaid plywood
    designations and addition of an appendix to detail the process for species grouping.
    C2.5 PS 1-09 Structural Plywood became effective May 2010
    In response to consumer complaints regarding thickness labeling being out of compliance with
    NIST Handbook 130 and 133, the standard was revised to create a Performance Category
    based on customary thickness notations used in U.S. model building codes. In addition, panel
    labeling requirements was changed to require the Performance Category and decimal thickness
    representation. Nonmandatory Appendices were added to provide recommended labeling and
    to provide guidance on quantity representations on bundles.
    In addition, nonmandatory Appendices were added to describe formaldehyde emission
    characteristics of PS 1 panels and how PS 1 panels align with various green building
    specifications.
    C2.6 Current edition, PS 1-19 that became effective December 1, 2019
    After considerable technical review by members of the PS 1 Standing Committee, the standard
    was revised to address the following technical and informational aspects. Additional details were
    added regarding measurement of dimensions. The term “sized for spacing” was added to denote
    panels that are sized for compatibility to recommended application for construction uses.
    Other technical and editorial revisions were made to reflect industry practices, including:
    57
    • Simplification of the Appendix on labeling
    • Deletion of the Appendix on Green Building Provisions
    • Revised definition of qualified testing and inspection agency
    • Added abbreviations commonly used for labeling
    58
    Appendix D. (nonmandatory)
    D1 Recommend thickness labels
    Section 5.10.2 specifies thickness tolerances and Performance Categories for plywood grades.
    Section 7.3.e specifies that the panels shall be labeled with a thickness label in 1000ths of an
    inch and that labeled quantity shall be within the minimum and maximum thickness specification
    for that Performance Category. Table D1 and Table D2 present recommended thickness labels.
    D2 Regulations on labeling
    See Appendix E for discussion of regulations dealing with labeling.
    TABLE D1. RECOMMENDED THICKNESS LABELING FOR UNSANDED,
    TOUCH SANDED AND OVERLAID PANELS
    Thickness Requirements for
    Unsanded, Touch Sanded and Overlaid Grades1
    Performance
    Category2
    Minimum Thickness
    in (mm)
    Maximum Thickness
    in (mm)
    Recommended
    Thickness Label(3)
    1/4 PERF CAT 0.219 (5.56) 0.281 (7.14) Thickness .225 in
    11/32 PERF CAT 0.313 (7.94) 0.375 (9.53) Thickness .322 in
    3/8 PERF CAT 0.344 (8.73) 0.406 (10.32) Thickness .354 in
    7/16 PERF CAT 0.406 (10.32) 0.469 (11.91) Thickness .418 in
    15/32 PERF CAT 0.438 (11.11) 0.500 (12.70) Thickness .451 in
    1/2 PERF CAT 0.469 (11.91) 0.531 (13.49) Thickness .483 in
    9/16 PERF CAT 0.531 (13.49) 0.594 (15.08) Thickness .547 in
    19/32 PERF CAT 0.563 (14.29) 0.625 (15.88) Thickness .578 in
    5/8 PERF CAT 0.594 (15.08) 0.656 (16.67) Thickness .609 in
    23/32 PERF CAT 0.688 (17.46) 0.750 (19.05) Thickness .703 in
    3/4 PERF CAT 0.719 (18.26) 0.781 (19.84) Thickness .734 in
    13/16 PERF CAT 0.781 (19.84) 0.844 (21.43) Thickness .788 in
    7/8 PERF CAT 0.831 (21.11) 0.919 (23.34) Thickness .849 in
    1 PERF CAT 0.950 (24.13) 1.050 (26.67) Thickness .970 in
    1-1/8 PERF CAT 1.069 (27.15) 1.181 (30.00) Thickness 1.091 in
    1-1/4 PERF CAT 1.188 (30.16) 1.313 (33.34) Thickness 1.213 in 1 1Thickness requirements for unsanded, touch sanded and overlaid panels are based on a tolerance of +/- 0.8
    mm (1/32 in) for panels with Performance Categories of 13/16 and less and +/- 5% for panels with Performance
    Categories greater than 13/16 unless a closer tolerance is determined through qualification testing. Inch units
    are presented as primary units due to customary practice in the United States.
    2 Acceptable abbreviations are PERF CAT, CAT or Category.
    3 The recommended thickness label for categories less than 9/16 is 3% above the minimum. The
    recommended thickness label for categories greater than or equal to 9/16 are the minimum values for
    sanded panels.
    59
    TABLE D2. RECOMMENDED THICKNESS LABELING FOR SANDED PANELS
    Thickness Requirements for
    Sanded Panels1
    Performance
    Category2
    Minimum Thickness
    in (mm)
    Maximum Thickness
    in (mm)
    Recommended
    Thickness Label3
    1/4 PERF CAT 0.234 (5.95) 0.266 (6.75) Thickness .234 in
    11/32 PERF CAT 0.328 (8.33) 0.359 (9.139 Thickness .328 in
    3/8 PERF CAT 0.359 (9.13) 0.391 (9.92) Thickness .359 in
    7/16 PERF CAT 0.422 (10.72) 0.453 (11.51) Thickness .422 in
    15/32 PERF CAT 0.453 (11.51) 0.484 (12.30) Thickness .453 in
    1/2 PERF CAT 0.484 (12.30) 0.516 (13.10) Thickness .484 in
    9/16 PERF CAT 0.547 (13.89) 0.578 (14.68) Thickness .547 in
    5/8 PERF CAT 0.609 (15.48) 0.641 (16.27) Thickness .609 in
    23/32 PERF CAT 0.703 (17.86) 0.734 (18.65) Thickness .703 in
    3/4 PERF CAT 0.734 (18.65) 0.766 (19.45) Thickness .734 in
    13/16 PERF CAT 0.788 (20.02) 0.837 (21.26) Thickness .788 in
    7/8 PERF CAT 0.849 (21.56) 0.901 (22.89) Thickness .849 in
    1 PERF CAT 0.970 (24.64) 1.030 (26.16) Thickness .970 in
    1-1/8 PERF CAT 1.091 (27.72) 1.159 (29.43) Thickness 1.091 in
    1-1/4 PERF CAT 1.213 (30.80) 1.288 (32.70) Thickness 1.213 in 1 Thickness requirements for sanded panels are based on a tolerance of +/- 0.4 mm (1/64 in) for specified
    performance categories of 3/4 and less and +/- 3.0% for panels with a performance category greater than 3/4 unless
    a closer tolerance is determined through qualification testing. Inch units are presented as primary units due to
    customary practice in the United States.
    2 Acceptable abbreviations are PERF CAT, CAT or Category.
    3 Recommended thickness labels for performance categories are based on the minimum permissible thickness for
    that category.
    60
    Appendix E. Labeling Guidelines Based on the Uniform Packaging and Labeling
    Regulations of NIST Handbook 130 and Handbook 133 (nonmandatory)
    E1 Summary
    E1.1 When intended for sale or distribution, the labeling of the panels should meet the
    requirements of the Uniform Packaging and Labeling Regulation. This section provides
    references to standards applicable to labeling and packaging.
    E2 Background
    E2.1 The National Institute of Standards and Technology (NIST) of the U.S. Department of
    Commerce promotes the development of standards to be applied across industry and supports
    the publishing of NIST Handbook 130, Uniform Laws and Regulations in the Areas of Legal
    Metrology and Engine Fuel Quality. NIST Handbook 130 is a compilation of the latest uniform
    laws and regulations regarding packaging and labeling requirements adopted by the National
    Conference on Weights and Measures, Inc. (NCWM) and is intended to represent standards to
    be adopted into law by the weights and measures jurisdictions of the United States.
    E2.2 Procedures used by Weights and Measures inspectors are included in NIST Handbook
    133, Checking the Net Contents of Packaged Goods
    E2.3 For information, a complete copy of the most recent version of NIST Handbook 130 and
    133 are available at:
    https://www.nist.gov/publications/
    61
    Appendix F. Formaldehyde (nonmandatory)
    F1 General
    Formaldehyde is a simple naturally occurring chemical made of carbon, oxygen and hydrogen.
    It is produced by the human body and animals and plants. It is also formed by combustion and
    is an industrial chemical widely used in the manufacture of many consumer products.
    Background information on formaldehyde and health concerns related to elevated levels in
    indoor air can be found at www.epa.gov/iaq/formalde.html.
    F2 Formaldehyde regulations
    F2.1
    There are no national or state regulations of formaldehyde emissions expressly stated for PS 1
    structural plywood. This is mainly due to the very low emission rates demonstrated by PS 1
    Structural Plywood.
    F2.2
    U.S. Department of Housing and Urban Development Rules and Regulations 24 CFR 3280 for
    manufactured housing includes § 3280.308 “Formaldehyde emission controls for certain wood
    products”, that deals with formaldehyde emissions from particleboard and plywood. The
    regulations establish limits for formaldehyde emission levels and ongoing evaluation
    requirements as follows (underlined emphasis added):
    (b) Product certification and continuing qualification. All plywood and
    particleboard materials to be installed in manufactured homes which are bonded
    with a resin system or coated with a surface finish containing formaldehyde, other
    than an exclusively phenol-formaldehyde resin system or finish, shall be certified
    by a nationally recognized testing laboratory as complying with paragraph (a) of
    this section.
    PS 1 Structural Plywood is made predominantly with phenol-formaldehyde adhesives. When
    made as such, it is exempt from the HUD requirements.
    F2.3 California Air Resources Board (CARB) Air toxic Control Measure for Composite
    Wood Products (see: http://www.arb.ca.gov/research/indoor/formaldehyde.htm)
    The CARB ATCM for Composite Wood was approved for implementation on January 1, 2009.
    The scope of the standard is particleboard, medium Density Fiberboard (MDF) and hardwood
    plywood. Section § 93120.1 “Definitions” explicitly excludes PS 1 Structural Plywood and other
    structural wood products from the scope of the standard as follows (underlined emphasis
    added):
    (8) “Composite wood products” means hardwood plywood, particleboard, and medium density
    fiberboard. “Composite wood products” does not include hardboard, structural plywood as
    specified in the Voluntary Product Standard – Structural Plywood (PS 1-07), structural panels as
    specified in the Voluntary Product Standard – Performance Standard for Wood-Based
    Structural-Use Panels (PS 2-04), structural composite lumber as specified in Standard
    Specification for Evaluation of Structural Composite Lumber Products (ASTM D 5456-06),
    oriented strand board, glued laminated timber as specified in Structural Glued Laminated
    Timber (ANSI A190.1-2002), prefabricated wood I-joists as specified in Standard Specification
    for Establishing and Monitoring Structural Capacities of Prefabricated Wood I-Joists (ASTM
    D 5055-05), finger-jointed lumber, or “composite wood products” used inside of new vehicles as
    defined in section 430 of the California Vehicle Code (excluding recreational vehicles), railcars,
    boats, aerospace craft, or aircraft.
    62
    F2.4 National “Formaldehyde Standards for Composite Wood Act”
    The Formaldehyde Standards for Wood Composites Act was signed into law on July 7, 2010. With
    respect to PS 1 panels, this law is identical to the CARB ATCM for Composite Wood (see Section F2.3).
    PS 1 panels are exempt from the scope of the Formaldehyde Standards for Composite Wood Act. For
    further information see: https://www.epa.gov/
    F3 Formaldehyde emission from PS 1 Plywood
    F3.1
    Information on formaldehyde emission from PS 1 panels is available from APA in Technical
    Note J330, Formaldehyde and Engineered Wood Products (see: www.apawood.org).