Earthbag domes are more fire resistant and safer in brush fires such as this one in Australia.

Earthbag domes are more fire resistant and safer in brush fires such as this one in Australia.


I received an email about the high fire risk in Victoria and much of southern Australia, and they explained how they are considering earthbag domes as a fire safety strategy. Wooden roofs, especially houses with roof overhangs, would be at much higher risk of fire than domes. Fire would go right on past a properly built earthbag dome with a little preparation.

Here is my email reply:
In addition to normal fire prevention strategies like planting fire-resistant plants around your house, creating a fire break by clearing brush a safe distance, and not storing combustibles such as firewood next to the home, all you really need to know is domes are much safer against brush fires than houses with roofs. Add metal shutters so you can close off windows and doors in case of fire. You might also want to add an air filter and stock up on water and other supplies so you can stay at home until the emergency is over. Please keep us posted of your project. Your home could be a model home for others in the area. This is really important to me. I hate seeing all the needless suffering caused by inappropriate building methods.

Disaster Resistant Earthbag Housing
Image source: Big Brass Blog


Comments

Earthbag Domes for High Fire Risk Areas — 18 Comments

  1. First of all, sorry for the translation of Google. I want to know if there are studies or experiments, concerning the strength of an Earthbag home in case of a nuclear blast (Atomic Bomb)? Of course, being duly protected under ground … Thanks, in advance.

    • Who would pay for tests like this? All we can do is go by what’s known. Armies for two hundred years or so have relied on sand bags for fortification/defense. There’s a snippet in my earthbag book about how munition bunkers in war zones are made of sand bags. If one bunker explodes, the sand bags protect the surrounding bunkers.

      There have been one or two tests done for bullet resistance and another one for hurricane resistance, where an earthbag wall was shot with 2x4s from a canon. All these tests and more are on our Testing page at Earthbag Building.com.

  2. I have no experience with fire, other then seeing large forest ones from a distance. Seeing those, one would think even the best constructed house, unless buried deep beneath the earth would become nothing more then a giant oven. There is also the question of oxygen. Super heated air/smoke or lack of O2 could easily kill you. If under ground, the vacuum created by the heat could pull air from the interior thru fresh air vents to feed the fire. I certainly wouldn’t want to weather a firestorm in any kind of a structure.

    The best solution is to rid the area around any building compound from combustible vegetation. Keep combustible building materials to a minimum and have an evacuation plan at hand.

    • What you say is true often times, but you have to weigh the risk case by case. Millions of people live in fire prone areas and lots of people choose to stay and protect their homes. Lots of places are not nearly as extreme as Victoria. Create a large fire break around a fire resistant home, store water and have a means to spray the water all around and on the structure and you can save your home in many situations.

  3. That sounded a little harsh, sorry… I doubt may Victorians would suggest staying and defending a house after 2009.

    There is a fine line between a house that is structurally fire resistant and a house that is safe to occupy during a bushfire.

    • No problem, I agree. It’s always good to hear the other side of the story. I’m surprised if people remain living in a place that extreme.

      Back to earthbag domes: You wouldn’t want to hole up at home during a fire in Victoria, but at least your home would be standing so you could get on with your life. Sure beats losing everything.

    • I am old enough to remember Ash Wednesday and the destruction through the Adelaide Hills, including Pyrex saucepans (rated to well over 1000 deg C) melten inside one another in the rubble. The one story that stands out, though we’re the family that stayed in their federation style home with the green bull-nosed verandahs. This house (as far as I know) is still standing just a short distance from the Pyrex pots: the difference between a well- prepared family and a vacant house full of wedding presents.

      If my house and family were well enough prepared, I would stay. If they weren’t and we left, I would expect to come home to rubble, regardless of the construction of our home. That’s just the way it is. I hope I can build and keep a house in a standard and condition where we would be in good shape to stay and defend. I pray I am wise enough to know the right decision to make at the time.

      By the way, thanks for being in the CFA. It’s a tough gig.

    • B the way, have you seen the pics online of timber houses still standing beside double brick piles of ash? Guess which was prepared and defended? I am not a big fan of the new building guidelines (?) that the Vic govt have released before the official findings on the differences between houses that burned and those that survived. Something of a cart Pre horse issue me thinks!

  4. I live in Victoria, I am a Country Fire Authority volunteer, I am on standby at the moment waiting to be called out… in Victoria and across Australia, bushfires are a way of life.

    Australian bushfires are not similar to any other wildfire in the world. Unless you understand our bush, you won’t understand the type of fire. Our trees contain highly flammable eucalyptus oil, and often explore during an intense bushfire.

    The 2009 fires (Black Saturday Fires) claimed 173 human lives, injured 414 and 2029 homes were lost. In an international context its the 8th deadliest bushfire. The fires travelled at close to 75mph/120kph due to the gale winds, background temperature was 46*C/115*F and the fire intensity was approx 820*C/1,500°F – 1330*C/2,420°F. The whole fire complex, released the approx energy equivalent to 1500 Hiroshima-sized atomic bombs.

    I completely disagree with Owen’s advice “so you can stay at home until the emergency is over”

    Yes the house may stand…. but i doubt in such a fire it would be safe to be an occupant.

    Wetting around the home is great prevention of amber attack. But don’t rely on Generators and pumps as the main fire front hits… they inevitably fail and overheat, suffocate on smoke, or can’t get enough oxygen.

    Best to listen to the CFA advise and get out of your property on high fire ratings, and be prepared to leave during low fire ratings.

    • Well, sure. Use common sense if there’s a fire equal to “1,500 atomic bombs.” Duh. I’m describing an option for many fire prone areas. Not all areas are equal. There are probably areas within Victoria that are lower risk than others. Research each area, weigh the evidence and make your own call.

  5. I’m in Australia too, and this is also one of the reasons I am considering earth(bag) construction.

    As far as the roof goes, I would like to do a living roof as I think this would give good protection from above and insulation.

    I wonder, though, about whether the polypropylene bags would let off fumes if the fire was around for a while and started to heat the thermal mass above what the bags could take. Would they be safe enough encased in an earth/like plaster?

    • See the other comments about “1,500 atomic bombs”. You have to evaluate your area and decide for yourself what makes sense. Nothing can withstand the most extreme forces of nature. This is similar to earthbag houses being seismic resistant versus seismic proof.

      There’s a blog post on this blog about an earthbag house that withstood a forest fire and was one of the only remaining houses in the area left standing. I could look it up if you can’t find it. Their house has several roundhouses joined together with living roofs. So stories like this validate what I’m saying, but again, nothing can withstand the most extreme forces of nature. That should go without saying. For instance, no one in their right mind would build right on top of the San Andreas fault or on top of a volcano.

  6. It’s also good to have a sprinkler system that is independent of the grid and municipal water supply, in case those systems are not functioning during a major fire (quite possible). A sprinkler system like this would require water storage (cistern, etc.), water pump and water lines to sprinklers, and independent power supply from batteries, portable generator, etc. You could water the domes and the area around your home.

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