It’s important to select claddings that are fit for purpose, but with so many options, how can you be sure about performance?
THE STARTING POINT for cladding selection is the compliance document for New Zealand Building Code clause E2 External moisture. Acceptable Solution E2/AS1 provides a logical flow of risk assessment using a risk score, offering a range of suitable wall claddings – both direct fix and over a nominal 20 mm cavity – together with associated construction details.
When a product or system complies fully with the requirements in E2/AS1, it is deemed to be an Acceptable Solution.
Claddings that don’t comply with E2/AS1
A proposed cladding system that does not fully comply with the Acceptable Solution is deemed to be an Alternative Solution and must be assessed by Verification Method E2/VM1 (cavity based cladding systems only). Weathertightness tests must be carried out at an International Accreditation New Zealand (IANZ) or equivalent accredited testing facility.
Product assurance framework
In April 2011, the Department of Building and Housing (now part of the Ministry of Business, Innovation and Employment) issued a guide to product assurance that provides a risk-based approach to appropriate levels of product verification.
Put simply, if the building product or system being considered needs to comply with the Building Code, the product assurance framework helps specifiers decide whether a relevant test, Appraisal or certification is needed from the manufacturer, importer or supplier to demonstrate Code compliance.
The product assurance framework suggests information is presented in a product technical statement that includes:
- statement of Building Code compliance – a clear statement of the New Zealand Building Code clauses relating to the product or system and a self-declaration of compliance with the performance requirements of these clauses
- scope of use – a statement using recognised New Zealand terms, such as wind, seismic and corrosion zones, outlining the product’s scope of use, including any conditions or limitations.
Appraisals provide confidence
BRANZ considers any Alternative Solution cladding system is high risk and needs the assurance provided by an Appraisal – a technical opinion of Building Code compliance and fitness for purpose by an independent competent body.
A BRANZ Appraisal assesses wall claddings as a total wall system, including associated components against a range of performance factors within a well defined scope of application. Performance (weathertightness, structural, durability, moisture, fire and thermal insulation) is assessed under test conditions as is the accuracy of technical information, manufacturing and site procedures, and quality control systems.
CodeMark product certification offers the highest level of product assurance. A CodeMark-certified product or construction method must be accepted by a building consent authority as complying with the Building Code when used as specified in the CodeMark product certificate.
Articles are correct at the time of publication but may have since become outdated.