AUST – Hendry advises that in recent years, residential and commercial buildings in Australia have seen a dramatic increase in the use of innovative, external wall cladding systems which are not covered within the Building Code of Australia (BCA) deemed-to-satisfy (DtS) provisions and building regulations. When these systems are proposed in the design of a new building or building upgrades they are required to be presented as Alternative Solutions. The Alternative Solution must include evidence that allows the relevant authority to determine that the material and the form of construction proposed in the design meet the Performance requirements in the BCA. It must also demonstrate it complies with the Performance Requirements of the BCA, or that it is equivalent to, or better than the DtS provisions.
Duties of Designer/Applicant
The applicant must also take care when specifying non DtS wall cladding systems and ensure sufficient evidence is given to the authority to make the appropriate assessment. This evidence should be submitted at the design stage of the project and include certificates, reports and forms.
Consequences of Failure of Non DtS External Wall Cladding Systems
Cladding systems must be designed to resist all actions, including live and dead loads, rainwater, wind, earthquake and thermal actions.
The cladding system must resist the egress of water into the building, which causes the loss of amenity for occupants and deterioration of building elements.
Where moisture may penetrate to the inside face of the cladding system, the moisture must be able to escape the building, either by ventilation of a cavity or natural drainage.