Bushfire Shelters

So to get our planning permit through, we needed to add a bushfire shelter. While we likely don’t need one, we’re not unhappy to have one, because I’m very risk averse.

Many states in Australia do not approve Bushfire Shelters due to the fear that people will chose to stay and defend their houses rather than leave early when a bushfire threatens. While it is likely that it will encourage people to stay – it does encourage us – its certainly safer to have one if you get caught in a fire.

There are four standard bushfire shelters from three providers are accredited in Victoria – you don’t need to have the design validated by the authorities, since the standard design is already approved.

As this list will likely change, approved shelters can be found at http://www.vba.vic.gov.au/building/building-regulations-advisory-committee. Search the register of accredited building products.

We rang the three providers, but selected Wildfire Safety Bunkers, based on cost and aesthetics:

Wildfire Safety Bunkers

These bunkers are built predominantly below ground, and rely on the insulation properties of the earth to provide the thermal protection. They come in two sizes – 6 and 12 people. We’re looking for the 6 person version.

They’re small – 2.6m long x 2m wide x 2.1m high, and accessed by a steep inclined ladder, have a viewing port, external temperature measurement and isolatable ventilation shafts. There should be enough air for 6 people for an hour when it is all sealed up.

We will be installing our bunker on a flat site and liked the look of this one – a small mound with just the door showing. It needs to be covered in non-combustible materials, with little vegetation near by, but should be relatively low visual impact.

The access is a little problematic – I have arthritic knees, and will need both replaced, so I expect I will have problems, but if I’m escaping a bushfire I’m sure the adrenalin will make access OK. I’ll just need to make sure my knee replacements are at the beginning of winter! Or bumslide down the marine stairs/ladder.

Given that we were required to specify our bunker to get our permit, and Melbourne was in covid lockdown at the time, we couldn’t test out the access.

It comes to site as a prefabricated unit, and is craned into position (truck delivery has a crane attached that can do most installations). Obviously, you have to dig a hole for it before it arrives.

One hassle is that you need a building permit to use it as a fire bunker, and they will not get the building permit for you. So you need to be an owner builder to apply for the permit. They will advise you of folk you can use in your area to dig the hole for you. If it isn’t an official fire bunker, you may not need a permit – your council may let you install a fire proof storage shed without a permit, however this is technically illegal if its actual purpose is as a bushfire shelter.

Website: Wildfire Safety Bunkers

This bunker is around $5k cheaper installed than Innovative Building Systems bunker.

Innovative Building Systems.

Above ground, this six person bunker relies on hebel blocks and claims to provide the thermal insulation for two hours. There is a below ground option. There are no access issues, and they can be made wheel chair accessible. There is very limited information on the website, with no sizing details, air capacity or ventilation details. It is accredited for use for a maximum of one hour for 6 people – one assumes this is due to air volume in the bunker.

You should not need to be in there for more than an hour, since flame fronts run through very quickly.

Aesthetically, we didn’t think this was as attractive. It can’t be surrounded or disguised with vegetation, and since it needs to be at least 10m from the house on our flat site it will really stand out. We could have got creative with painting, but…

Website: ibsystems.net.au

Frankston Concrete Products

At the time of enquiry, they were not making their accredited fire bunkers. They were thinking about restarting it, so worth checking back in.