Recent updates made to the Building Code of Australia, which came into effect on May 1, 2015, have changed the weatherproofing requirements for all buildings, and include a new verification method. To assist builders and specifiers meet these new requirements, Cemintel has developed a number of solutions and support tools.

The BCA’s increased focus on weatherproofing addresses concerns in markets with similar construction practices, such as Canada and New Zealand and locally via the Victorian Building Authority. Builders and specifiers can now ensure compliance with BCA Performance Requirements using one or a combination of four different assessment methods.

These include:

  1. A new verification method developed by an ABCB working group specifically to focus on the issue of weatherproofing. This is a test procedure suitable for walls of some buildings with limited design wind pressures.
  2. Evidence to support the use of a material form of construction or design that meets Performance Requirements or a Deemed-to-Satisfy provision. A CodeMark Certificate of Conformity is one way to achieve this option, and has mandatory acceptance.
  3. Comparison with a Deemed-to-Satisfy provision, where applicable.
  4. Judgment by a suitably qualified expert to determine whether a solution complies with the Performance Requirements.

Referencing the Australian Standard AS/NZS 4284: 2008 ‘Testing of building facades’, the new verification method covers three types of systems based on a risk assessment matrix:

  • Cavity wall system - a wall that incorporates a drained cavity
  • Direct fix cladding system - a wall with cladding attached directly to the wall framing without the use of a drained cavity
  • Unique wall system - a wall, which is neither a cavity wall nor a direct fix cladding wall

Based on Cemintel’s testing and examples from markets with similar construction practices, the best means of weatherproofing a building is via a drained and ventilated cavity. Cemintel Marketing Manager Ben Thompson observes that the recent BCA changes reflect this move towards greater cavity use.

According to Ben, cavity systems are already a major feature of building codes in countries with similar construction methods such as Canada and New Zealand, and the verification method in the Draft BCA 2015 states that cavities must be used on buildings with a high score on a risk assessment matrix. He notes that although this requirement was removed from the final BCA 2015, there is a possibility it may feature in future editions.

Ben explains that cavity systems offer a number of advantages in preventing water penetration. Buildings with cavity systems also perform better in high wind zones; have a lower reliance on sealant; and allow air to circulate more effectively. Cavity systems also allow water to evaporate and escape helping to better manage any moisture in the building.

He adds that Cemintel provides a number of cavity options to suit various site requirements. Cemintel’s Designer Series is an excellent example of a practical and affordable walling solution that offers a stylish and creative design aesthetic while incorporating a ventilated and drained cavity. The unique clip system used to install Designer Series panels provides a 15mm open cavity without the additional cost of battens.

Cemintel’s wide range of cladding sheets and weatherboards used over structural or non-structural battens offers another solution to builders looking for a ventilated and drained cavity system. Cemintel’s durable, fibre cement battens can be used in structural or non-structural applications. As a structural batten they are ideal for flat sheet products such as Cemintel Mosaic with the panel fixed to the batten using brad nails to minimise the appearance of fixings. The fibre cement battens also represent a durable alternative to timber when used as a non-structural batten.

The verification method also includes the direct fix system, which is most suitable for less complex buildings in lower wind load zones, and the unique wall system comprising of direct fix or cavity systems. Cemintel’s wide range of cladding sheets and weatherboards can be used in direct fix applications while the ExpressWall system is a great example of a unique system suitable for use even in cyclonic regions.

To help builders comply with these changes, Cemintel has introduced a number of support tools to assist them in choosing suitably assessed cladding systems.

Details are now available for all Cemintel sheet cladding and weatherboard products that have been assessed as meeting the weatherproofing requirements. CSR and Cemintel are also introducing a series of support materials and information events to help guide builders through the selection process.

CSR’s nation-wide Building Knowledge Seminar, running from June 9th to August 25th will cover the topic of Moisture Management and the use of cavities in buildings. Builders and specifiers attending these events can earn CPD points.

Cemintel’s new cavity systems guide contains information on the new weatherproofing clause and details on the new ventilated and drained cavity developed for its sheet cladding and weatherboard solutions. Cemintel’s DesignLINK technical support line is also open to answer questions on the BCA developments and their application.