Window wind zones

By and - , Build 129

Recent changes to NZS 3604:2011 Timber-framed buildings and NZS 4211:2008 Specification for performance of windows has created an inconsistency between wind zones in these standards.

NZS 3604:2011 introduced an extra high wind zone based on a maximum site wind speed of 55 m/s, while NZS 4211:2008 introduced an extreme wind zone based on a maximum wind speed of 60 m/s.

Interim solution

A set of test pressures has been calculated for NZS 4211:2008 based on the new extra high wind speed used in NZS 3604:2011 and in the revised E2/VM1. The pressures (see Table 1) can simply be added to NZS 4211:2008 Tables 1, 4 and 5.

Windows with an extra high rating will then be able to be used in locations with a site wind speed up to 55 m/s, which aligns with NZS 3604:2011.

Extreme wind zone

Windows can be rated to perform in the extreme wind zone in NZS 4211:2008 (which applies to locations where the site wind speed is between 55 and 60 m/s), but the claddings and installation details must be the subject of specific design.

Table 1: Annotations needed to tables in NZS 4211:2008 to align wind zones with NZS 3604:2011.
Table 1 SLS test pressures Extra high ±1,515 Pa
Table 4 Water test pressures Extra high 455 Pa
Table 5 ULS test pressures Extra high ±2,130 Pa


A future amendment to NZS 4211:2008 is expected to include this solution.

Download the PDF

More articles about these topics

Articles are correct at the time of publication but may have since become outdated.