Understand the testing protocols for cladding materials and external wall cladding systems.
Cladding materials and external wall cladding system
For the purposes of the requirements in C/AS2, C/VM2 and this guidance document 'cladding materials' are the exterior components including cladding, rigid air barriers, insulation products, sheet materials or blankets and filler materials (not including gaskets, sealants etc.). This does not include other components that make up an external wall cladding system such as the structural framing or interior linings. The 'external wall cladding system' inherently includes framing elements and other components used to construct the wall, in addition to the cladding materials. Refer to the section "Fire test methods for external wall cladding system" for additional details.
Fire testing external wall cladding systems
Section "Fire test methods for external wall cladding systems" provides a description of common components that can be assessed in small-scale tests of the cladding materials as well as what can be assessed as part of the external wall cladding system. This section also contains a list of items that are not required to be included in the fire tests.
Framing for an external wall cladding system
Cladding systems are intended to protect the inside of the building from the weather on the outside. Framing necessary to support the cladding system is required to be considered in the design.
Traditionally, fire tests for cladding systems did not consider the contribution of structural members to the spread of fire. This is because the international building codes at the time would have restricted the use of combustible structures or structures containing combustible elements to certain prescribed building heights only. The consequence is that fire testing has not been required to address combustible structural elements because they would have not been permitted in the first place.
Section "Fire test methods for external wall cladding systems" discusses what elements can be tested with different fire tests.
Minor variations to a tested external wall cladding system
In some cases, a minor variation to a fire tested cladding system can be assessed by an accredited testing laboratory or a subject matter expert with knowledge and experience in fire science and fire testing.
Requirements for existing buildings
There is no requirement to retrofit existing buildings or replace cladding materials under normal circumstances. Existing buildings undergoing alteration or a change in use are subject to provisions in section 112 and section 115 of the Building Act 2004. Compliance is determined on an as nearly as is reasonably practicable (ANARP) basis.