Sprinklers and shutters
This section describes bushfire shutters and external spray systems which are attached to the house or other external building elements (such as decks and verandas). Both are active systems and need to be deployed manually or by an automatic system.
Sprinkler systems – guiding principles
Sprinklers are active bushfire protection systems, which means their effectiveness depends on them being switched-on when needed and then continuing to operate for the duration of the fire. Sprinkler systems can aid in the survival of buildings (and people) during a bushfire, although installing an effective system can be difficult when working within a budget. Some people prefer to use passive design solutions in their build (such as installing barriers and open spaces between the house and the bushfire hazard) – or to manually wet the house using garden hoses and standard lawn sprinklers. Each option has its own strengths and drawbacks. Consider what works best for your situation, and plan accordingly. For a new build it will be a more cost effective and reliable solution to use passive measures such as non-combustible materials. However, when retrofitting an existing building this may not be feasible and bushfire sprinkler system may be preferable.
Use your sprinkler system to wet the buildings façade (including walls, eaves, and rooftops) and any vegetation and fine debris in the immediate vicinity of the home. Do this as the bushfire approaches your home and until long after the fire front has passed. Wind-driven embers can arrive long before (or after) the fire front reaches your location. For more information, see AS 5414:2012 Bushfire water spray systems.
Shutters – guiding principles
Non-combustible shutters offer protection against flame contact, embers, and strikes from flying objects. Shutter systems should be tight fitting with gaps less than 2mm to avoid ember entry and made with non-combustible material. The shutter must comply with AS3959:2018. As an active system, the shutter must be manually closed to be effective; consider using an automated system to close the shutter.
An external spray system (source: Paul Whittington)
- When designing your system, make sure to use metal pipework and heads, as plastic hoses and fittings will likely fail during a fire.
- If possible, ‘complement’ the external system with internal sprinklers.(ideally they would be separate systems). This will help suppress any internal house fires that may occur.
- Use non-combustible materials.
- Use the system to address specific weaknesses that can’t be remedied through siting and design.
- Ensure sprinkler systems are fed by a reliable water source.
- Consider using additional sprinkler heads in the roof cavity, and underfloor spaces – especially if they contain or are composed of combustible materials.
- Consider using a system which can activate automatically using a combination of smoke or heat sensors. Don’t rely on someone being at home.
- Think of the system as an an additional redundant measure (or as a last line of defence), rather than as your primary means of protection.
- Do not rely on active water pressure to feed the system – the system should operate using a passive water supply.
- Do not use a system that requires a manual start-process which has to be switched on in an exposed location.
- Do not use sprinklers to replace sealing gaps in order to prevent ember entry.
- Do not use a system that requires refuelling in order to provide the minimum duration of water delivery (a minimum 4-hour supply is recommended).
- Do not use exposed pumps and generators – all pumps and generators should either be shielded or installed within the buildings envelope.
- Do not rely on the mains electricity grid.
- Do not rely on the mains water supply.