Issue 35 – February 2012
Plywood sheets that are specified and installed to provide bracing must be identifiable. AS/NZS 2269 Plywood – Structural – Specifications requires that the sheet is marked with:
- the manufacturer's name
- the reference Standard – AS/NZS 2269
- the word 'structural' or a description of the product
- visual face grades (defining the face and back surface veneer quality), for example, CD has a C grade face veneer and a D grade veneer on the back
- the sheet glue bond type
- the sheet stress grade
- the panel construction code.
The markings indicate that the plywood has been tested and is suitable for use as a structural material. There are currently three manufacturers of structural plywood in New Zealand that have product tested to meet AS/NZS 2269 – Carter Holt Harvey Woodproducts, International Panel and Lumber, and Juken New Zealand.
The P21 test is used for plywood bracing, so make sure the required fixings that were used in the P21 test are used when the sheet is installed. Fixings and hold-downs must be the specifically identified type and at the spacings given in the manufacturer's technical manual.
Do not use installation and fixing instructions from one of the above suppliers for plywood sheet bracing that is not supplied by them.
Avoid using unbranded (cheaper) material for structural situations that require not less than 50-year durability – its performance cannot be guaranteed over the life of the structure. Where an unbranded product has been used, it is likely that it will have to be removed, as the consented documents are not likely to have been followed.
For further information, see the Build 121 article Structural plywood, available for free from the BRANZ website.