Natural disaster design tips
As the aftermath and cleanup of the devastating floods on Australia's east coast continue, NSW Planning Minister Anthony Roberts, revoked a requirement to consider the risks of floods and fires before building new homes. The minister has defended his actions by claiming that affordable housing is the more important priority.
At the same time, the Flood Resilient Building Guidance for Queensland Homes proved its worth by protecting more than 140 homes during last month's deluge, allowing families to clean up and safely move back in within days.
The obvious incentives for future-proofing your home are coupled with an immediate financial one. Many insurance companies will offer reduced premiums for customers who have implemented these measures and some states, like QLD, are offering financial assistance to residents who live, for example, in a flood-risk zone to upgrade their existing homes or build new homes in accordance with the guidelines. So what can you do to prepare your home for natural disasters?
Understanding the risks
The first thing you can do is understand the risks of the area you live in. For floods, a surveyor can give you a spot level of your ground floor and your local council can advise whether you're affected by overland flow, creek or riverine flooding. Knowing what types of flooding your home may be vulnerable to will reveal how long it could be exposed to water during a flood and what building materials to implement and avoid, as well as mitigating measures to take.
For fires, where your property is and the environment around it are important. For example, bushfires behave differently to grassfires and understanding these differences can help you future-proof your home. Each state has information on bushfire prone areas which you should consult before buying or building.
Mitigating the risks
i. Floods
There are some practical building upgrades you can take to make your home more flood resilient. Some ideas include wet-proofing the lower level of a home by installing polished concrete or tiled floors, which can significantly reduce cleanup and recovery efforts following floods. Installing louvres in the walls of the lower level of your home to enable water to easily flow through the home during a flood can reduce damage caused by trapped water. Widening the stairs from the lower level of your home will allow you to easily move furniture upstairs ahead of a flood to protect your possessions.
Any cavity or gap between building materials, like the void between exterior cladding and an internal wall, is an important consideration for upgrades or new builds as these gaps can retain water for longer causing mould issues following a flood. Constructing walls from core-filled blocks or single-skin polycarbonate to eliminate cavities that can hold moisture and silt is recommended. Constructing perimeter fencing to help floodwater flow away can also be useful.
Keeping up with home maintenance and re-thinking material choices for items like kitchen cabinets and door frames could also save home owners money in the long run. For example, using hardwood timber frames, rather than pine, because hardwood is less susceptible to mould and swelling.
ii. Fires
A Bushfire Attack Level (BAL) assessment can provide information on the severity of a home’s risk to ember attack, radiant heat and direct flame contact. BAL is measured in terms of radiant heat (kilowatts/m²), with the following relevant BAL ratings:
Bal LOW: Very Low Risk
BAL 12.5: Low Risk
BAL 19: Moderate Risk
BAL 29: High Risk
BAL 40: Very High Risk
BAL FZ: Extreme Risk
Planning regulations vary by state, however, these generally include sealing roofs, sealing around doors and windows and screening windows. The important things to consider for fire-proofing your home are:
External Cladding - corrugated iron is a sound choice for a fireproof house, as are some types of fibre cement panelling.
Timber - fire resistant timbers include turpentine, red ironbark, blackbutt, merbau, red river gum, spotted gum, and silvertop ash.
Windows - external metal shutters on all windows are recommended, as well as using aluminium or metal reinforced PVC for window frames.
House Frames - steel frames are a good choice because they are extremely durable and also fire resistant.
Gardens and landscaping - ensure that there is a 5m gap between house and garden and set the house as far as possible from native trees, also ensure gutters are cleared regularly. Sprinkler systems are also extremely useful and should spray water that is pressured to 300kpa.