Building Controls Update No. 127: P21 (2010) Wall bracing test and evaluation procedure
10 February 2012: From 1 February 2012, all users of the Acceptable Solution B1/AS1 document must follow the latest version (Amendment 11), which references NZS 3604:2011.
This means that from 1 February 2012, all wall bracing unit ratings must be based on the new P21 (2010) protocol.
An updated procedure for testing and evaluating wall bracing systems
The December 2011 Codewords article on wall bracing referred to NZS3604:2011 and BRANZ Technical Paper P21 (2010).
The new P21 (2010) protocol combines the testing and evaluation procedures for assessing the capacity of wall bracing systems into a single document. It resolves a number of ambiguities, and therefore avoids potentially different interpretations between testing laboratories.
Existing bracing systems based on old protocols
Where bracing systems have been based on earlier versions of the P21 protocol, re-testing is not generally required. However, the bracing unit ratings must be re-calculated from the original test results to align with the new P21 (2010) evaluation procedure. This usually results in a reduction in the bracing unit rating for the system, particularly for short panels.
If you make or sell bracing systems
If you make or sell bracing systems with published bracing unit ratings, and want to claim compliance with NZS3604:2011, contact your testing laboratory. Ask them to re-evaluate your existing ratings to bring them into line with the new P21 (2010) protocol. More about the BRANZ P21 technical paper
You can read the BRANZ paper below.