Marine Plywood British Specification BS 1088
BS1088-1:2003
The British Standard BS1088 in its various edicions is the mostly widely followed around the world. In particular, the plywood mills of South East Asia manufacture plywood which they describe as Marine Plywood and to which they apply a stamp stating that it is BS1088.
We see much plywood stamped as BS1088 which does not comply with the requirements of BS1088, none the less, in many cases, it is quite usable in boat building. The main non compliance that we see is core gaps well in excess of the standard and face veneers which are thinner than the standard permits.
So what does BS1088 say. Unfortunately, we can’t publish it here because it is a copyright document. Instead here is a summary of its more significant requirements. For any important use, we recommend that you purchase a copy of the standard to ensure that you have the official definitions.
Face Veneer:-
Free of defects except for :-
- Up to 6 pin knots per square meter.
- Maximum of 2 closed splits per metre of width of the panel, with a total length of 200mm
- No open splits
- Up to 2 small worm holes per square meter.
- No fungal decay.
- Low contrast colour variation.
- No repairs
- Glue penetration in the area adjacent to a permitted defect up to a maximum of 5% of the area of the outer ply.
- Up to 5% of sapwood is permitted.
Thicknesses:-
- For ply of 3mm thickness, minimum face thickness approx 0.6mm, maximum approx 0.9mm
- For ply of 3.6mm thickness, minimum face veneer thickness approx 0.7mm. maximum approx 1.1mm.
- For ply thicker then 3.8mm, minimum face veneer thickness to be 1mm.
Core Veneers:-
Permitted defects include
- No limit on pin knots
- No limit on closed splits
- Maximum of 1 open split of up to 0.5mm on any panel edge. (Core Gap).
- Small worm holes are OK.
- No limit on edge joints.
- Maximum of 3 repairs per square metre of a size less than 60mm, and grain aligned with the repaired veneer.
- Up to 5% of sapwood is permitted.
Maximum thickness to be 4.8mm
Plywood Panel Construction:-
- Adjacent plies to be laid with their grain at right angles.
- Minimum of 3 plys for panels less than 6.5mm thick.
- Minimum of 5 plies for panels thicker than 6.5mm.
- Not less than 40% of the grain and not more than 65% of the grain can run in any one direction.
- The panel is to be built with veneers on either side of its centre line matched in thickness, timber type, cutting method and grain direction.
- The centre veneer can be made up of two veneers glued together with their grain running in the same direction.
- Must not have core gaps (but see above under core veneers permitted defects) overlaps, pleats, blisters, hollows, bumps or imprints.
Permitted Timber Species.
- Any species which has at least a natural resistance to fungal attack as set out in BS EN 350-2.
- Standard plywood is made from species with a density of greater than 500kg/ cubic metre and a fungal resistance rating of Class 3 or better.
- Light weight plywood is made from species with a density of less than 500kg per cubic meter and a fungal resistance rating of at least Class 4.
Glue
- The glue has to be either a melamine-formaldehyde (amino) resin containing sufficient resorcinol (or other phenol) to provide a bond which can meet the glue test specified in BS EN 314-1 , or
- A phenolic resin.
- Glued edge joints are to be made with phenolic or an aminoplastic resin with a moisture resistance standard MR or better.
Marking
The BS1088-1:2003 requires the following infomation to be included.
- BS1088-1:2003
- UNBALANCED (if the panel is constructed in an unbalanced way.
- TREATED if any rot treatment has been applied.
- the nominal panel thickness
- manufacturers name or mark
- country of manufacture
- panel type, standard or light weight
- name of the timber species
e.g. BS 1088-1:2003 MARINE/3.6mm/MD/Malaysia/LW/Gaboon
