(BS) EN 324 -1: 1993
Wood-based Panels โ Determination of thickness, width and length
Part 1 gives methods for measuring the thickness, width and length of wood-based panels. It applies to whole flat boards.
Thickness
- A micrometer or similar measuring instrument having flat, parallel measuring surfaces of 16mm (ยฑ 1) diameter and an operating force of 4N (ยฑ 1) and graduated to allow readings to 0.05mm. Measurements are taken at approximately 50mm from the panel edges at points in each corner and in the middle of each side โ 8 no. points in total per panel. Readings must be within 1% of the thickness but to be not less than 0.1mm. Average the 8 no. readings and express this figure to the nearest 0.1mm.
Length and width
- Measure both the length and width of each panel along two lines parallel to and at a distance of 100mm from the edges to an accuracy of 0.1% but not less than 1mm. Average the two readings each for length and width and express the results to the nearest 1mm.
In comparison โ APAโs method for calculating the thickness, length and width:
Thickness
- Measure using a micrometer having anvils of diameter 19.1mm (+1.3mm/ โ 0) or 3/4โ (+ 0.05โ/ -0) and an anvil pressure of not less than 34 kPa (5 psi) and not more than 69 kPa (10psi).
- Measure mid-width on one end of a panel. If the measurement is below minimum or above maximum requirements, then three additional measurements shall be taken โ one at approximately mid-width on the opposite end and one at approximately mid-length on each side of the panel.
- Calculate the average of these 4 readings. If the average lies between the minimum and maximum thickness for that specific performance category, then the panel is acceptable; if it is outside the minimum or maximum tolerance, then the panel is below/above thickness.
Performance Category thickness and tolerance for APA plywood panels
This is in line with US PS 1-19 Structural Plywood and US PS 2-18 Performance Rated OSB.
APA Plywood | PerformanceCategory | Tolerance | |
---|---|---|---|
inches | mm | ||
SandedUnsanded | โค3/4>3/4 | ยฑ0.016 (1/64)ยฑ3% | ยฑ0.4ยฑ3% |
Touch sandedOverlaid | โค13/16>13/16 | ยฑ0.031 (1/32)ยฑ5% | ยฑ0.8ยฑ5% |
Length and width
- A tolerance of + 0mm, โ 1.6mm (1/16โ) should be allowed on the specified length and width.