Timber for window and door reveals in NZS 3602: 2003
Issues of concern
Specifiers, manufacturers and end users of aluminium windows and doors are required to nominate in their consent applications, the timber being used for the reveals. This is because the usual method of attachment of the windows is by fixing through the timber reveals to the building structure and the minimum performance requirements for aluminium windows and doors therefore depends in part on the durability of the timber reveals.
In selecting timber for the reveals, allowance must be made for possible intermittent wetting from condensation runoff or leakage through the aluminium frame mitres, by selecting suitable durable timber or pinus species with appropriate treatment levels.
NZS 3602: 2003 is the relevant Standard cited in the Department's B2 Compliance Document, B2/AS1 for Durability and in the new E2/AS1 for External Moisture. The durability requirements for window reveals are clearly given in Table 2 as 'members exposed to exterior weather conditions and dampness to achieve a 15-year durability performance'.
New Zealand Standard NZS 3602: 2003 Timber and Wood-based Products for Use in Building - Table 2: 2A.6 lists the following four species and treatments for reveals that may be expected to last the minimum performance life of 15 years under normal conditions.
Allowable timber species and treatment requirements for the full range of building elements are provided in NZS 3602 which can be purchased from Standards NZ, 0800 735 656. www.standards.co.nz