Multi-layered walls: Weatherproofing for rear ventilated facades

In the Australian design and construction industry, external facade systems have been the focal point of compliance issues in recent years. A 2019 Deakin University study examining 212 building defect reports found that moisture and water penetration issues affecting the building fabric were common across Australia.  The main cause of such issues were non-compliant or poorly-fitted cladding, or ineffective waterproofing in general.

The facade and cladding system is one of the most important aspects of a building from a design perspective, especially its ability to withstand Australia’s demanding climate. The National Construction Code (NCC) imposes demanding requirements for the weatherproofing of external walls to prevent unhealthy or dangerous conditions, or loss of amenity for building occupants, and undue dampness or deterioration of building elements. Designers and specifiers have sought new approaches to building facade design and construction to deliver top tier performance, weather resistance and compliance with these requirements.

Rear ventilated facades (RVFs) are gaining in popularity with design and construction professionals. There is growing awareness of the advantages of RVF systems, particularly the extra layers of weather protection they provide to external walls. While understanding of the design principles of RVFs is improving, there is still some confusion as to the relevant weatherproofing requirements and the corresponding testing procedures used to verify compliance.

In this whitepaper, we take a closer look at RVF systems, their benefits in modern building design, and outline the key performance requirements and testing procedures relevant to weatherproofing such systems.