The BSA has investigated a number of complaints involving defects with the use of expanded foam-based external wall claddings.
The defects generally relate to water penetration into buildings (primarily around door and window openings and at exposed edges) and the failure of rendered coatings to remain affixed to the foam substrate. There appears to be heavy reliance on the use of flexible sealants (which shrink and fail) for weather protection to openings, rather than permanently installed flashings capable of lasting the life of the buildings.
Please be aware that expanded foam-based wall cladding products are not captured by the deemed to satisfy provisions of the BCA.
Accordingly, they must be assessed as an alternative solution against the BCA’s performance requirements. Applications for building approval including the use of an alternative solution must be supported by documents demonstrating that the use of the material or form of construction will meet the performance requirements. Only if all relevant performance requirements are achieved can approval be granted. Readers may be familiar with the CodeMarkTM certification scheme. If a building element is covered by a certificate of conformity given under the scheme, the element is, to the extent stated in the certificate, taken to comply with the BCA. Some proprietary wall cladding systems have gained CodeMarkTM certification and the certificate of conformity for these products may be used to evidence the product meeting BCA performance requirements. However, care must be taken when relying on the certificate of conformity as it may not certify the product against all relevant performance requirements applicable for use as an external wall cladding.
It is therefore necessary for all parties, including the building designer, builder and building certifier, to correctly identify the relevant performance requirements under the BCA and to ensure they are fully satisfied. Considering the life expectancy of buildings and the conditions to which external wall claddings may be exposed, the defects witnessed by the BSA raise questions about material suitability and the appropriateness of some weather protection measures being employed.
The defects also raise serious questions as to whether the performance requirements for structural stability, dampness and weatherproofing under the BCA are being properly addressed by the parties involved. Further reading: Refer to the Victorian Building Commission’s fact sheet titled “Beware of noncompliant external wall cladding systems”.
Some manufacturers of polystyrene and other external wall cladding systems have
opted to have their products assessed and reported on by the CSIRO. These reports
can be found at http://www.cmmt.csiro.au/services/appraisals/..
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