Siniat’s rigid air barrier board Weather Defence is mainly used in ventilated façade or rainscreen systems. One of the best features of Weather Defence is that it provides the quickest way to achieve a weathertight building, allowing internal trades to keep working in inclement weather conditions. It is safe and easy to work with and is classified vapour permeable Class 4.
It can also be used in various applications where fire resistance is a requirement.
Being a plasterboard product, it is classified as non-combustible in terms of the NCC, making it suitable for use in external walls of high rise buildings. However, Siniat’s technical team have recently subjected the product to further fire tests, and it is now certified for use in various fire-rated systems where an FRL is required.
Weather Defence is certified for use in the following situations and applications that require fire resistance:
External Fire Spread
In the wake of several tragic building fires around the world, including the Grenfell Tower fire in London (2017) and the Lacrosse Tower fire in Melbourne (2014), combustible façade systems have become a pressing topic for building professionals.
In the event of a fire, a combustible façade can act as a fuel source, allowing flames to rapidly travel up the exterior of the building, often bypassing internal fire stops and containment systems.
There are two ways of testing for non-combustibility in a façade system. One option is to do a stringent full-scale fire test in which case a 9m structure is constructed and its performance in a fire is tested.
The other option is to use products that are deemed-to-satisfy in terms of the NCC and therefore don’t require additional testing for combustibility. Plasterboard and fibre cement are examples of deemed-to-satisfy products.
Weather Defence is a plasterboard product and may be used wherever a non-combustible material is required. It can therefore safely be used as part of a non-combustible façade system.
Further reading: Fire protection in high-rise residential buildings.
External fire-rated wall systems
Fire-rated external walls protect people and property on the inside when a fire threatens a building from the outside. They also provide protection when there’s a fire on the inside of a building, keeping the walls from collapsing, especially when they are loadbearing.
Siniat has conducted fire tests on a range of wall systems and certified their fire-rating. When used in a system, Weather Defence can provide an FRL (Fire Resistance Level) of up to -/120/120 or 90/90/90 when required by the Building Code of Australia.
Fire-rated systems incorporating Weather Defence are described in the Siniat technical manual Blueprint.
For more information about FRLs, read our blog How to select a fire-rated wall or ceiling.
Also refer to our blog Understanding group numbers and non-combustibility
External walls, ceilings and roof in bushfire zones
Another application where Weather Defence can provide excellent protection in the event of a fire is in the construction of residential buildings (Building Classes 1-3) in bushfire zones. Weather Defence can be used to wrap the entire building including the walls, roof and eaves to protect the occupants and contents during a bushfire.
Weather Defence has been assessed for use on timber and metal frames, and for both metal and tiled roofs. It can also be used on external ceilings in balconies and alfresco areas.
When using Weather Defence in this way, it can provide extra protection against an ember attack. An ember attack is a dangerous fire behaviour in which burning embers - also known as firebrands - are carried by wind from a wildfire or structural fire and land on or near buildings, vegetation, or other combustible materials, potentially igniting new fires far ahead of the main flame front.
Because Weather Defence can improve the weathertightness of a building, it has the added benefit of preventing smoke and dangerous gases from entering the structure.
A detailed installation guide of this application of Weather Defence will be made available soon. In the meantime please reach out to our technical team for more information.
Further reading: Building in bushfire-prone areas