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How can we build houses that better withstand bushfires?

As we are currently witnessing, transferring the suburban house into a setting susceptible to bushfires causes a lot of problems. Put simply: if you are going to live in a bushfire area you should expect…

Transplanting the suburban house to a bush setting needs a rethink. AAP Image/Lukas Coch

As we are currently witnessing, transferring the suburban house into a setting susceptible to bushfires causes a lot of problems.

Put simply: if you are going to live in a bushfire area you should expect to live in a home that is designed and built differently. Our challenge is to create a new, better architectural form for bushfire-prone areas, and to develop a way to upgrade existing homes.

Building to a standard

Regulators have sought to improve the bushfire protection of the standard Australian house by implementing measures from the Australian Standard 3959.

This standard improves the fire performance of each building component but as yet does not describe how these components could be assembled into a building. This design process is particularly complex; there is no one perfect solution but rather a variety of options that can be selected for any individual building site.

Many organisations have been working in this area: CSIRO, the Australasian Fire and Emergency Services Authorities Council (AFAC), the Bushfire CRC, a number of the state and territory fire agencies and Australian tertiary institutions. I have been researching this area for my PhD, and hope my findings can push the process ahead a little.

I asked residents in bushfire-prone areas which parts of their home they would take shelter in during a bushfire and which parts they would avoid. What was surprising was the large range of responses for both these questions.

While the bathroom was the most popular choice for taking shelter, with a focus on the ground floor to facilitate escape, there were up to 16 other places where residents plan to take shelter during a bushfire.

There were up to ten different places residents would avoid during a bushfire. They fall into four main categories: spaces with large amounts of glass facing the fire threat; lounge or living rooms; upstairs (because of limited escape) and the parts of the house closest to the direction of the anticipated bushfire threat.

Houses could be built into the side of a hill. Les Stockton

Architects could use this knowledge when designing future homes in bushfire-prone areas. Bathrooms for example could be located at the junction of two outside walls and include an external door. Large expanses of glass facing the direction of the fire threat could be replaced with low walls with windows above.

The same residents were asked how their house could be improved to withstand a bushfire. They suggested bushfire shutters, roof sprinkler systems, non-combustible decking and verandas, mesh flyscreens, an underground area and increasing the cleared area around the house. If incorporated, each of these would have to be validated, tested and improved by industry experts. An example being rooftop sprinklers systems which require both a water supply and a generator to function. If the connections for either of these are inadequate the system will fail. Further research may produce ways to improve the reliability of these components.

There will need to be more work done on the materials we can use for future buildings. Researchers should also look at alternative options, such as having part of the house constructed underground or bermed into the side of a sloping block.

Not all is lost

Somewhere among the heartbreak of losing a home is the future opportunity to rebuild better than before.

This is a chance to not only improve the fire protection of the house but make it energy efficient by trapping, storing and reusing energy and water. This is particularly relevant when the supply of grid power and mains water are interrupted, restricted or cease altogether during a bushfire.

Thought should also be given to making the home a pleasant place to live; one that nurtures family life and individual reflection.

All of these things are achievable. But building such a house requires residents to change some of their perceptions about how their home will look and function.

Future homes are likely to be smaller, with fewer windows and no external timber. They will also require regular maintenance, keeping energy efficiency devices in good condition, and maintaining the carefully planted and cleared area around the house.

Making bushfire responsive houses affordable to the majority of residents is a challenge that the architecture profession may wish to contribute to in a number of ways. Architects could elect to volunteer their services and help individual families to rebuild. This however is a large and time consuming task.

An architectural competition could be set up to find the best cost-effective home designs which mitigate or remove the ways flying embers and direct flame contact from a bushfire gain entry into a house.

Having a resource of pre-prepared designs would be good: the painful dilemma of research in this field is that it takes time, and residents who have recently lost their homes have very real needs right now. For me it’s personal, as many of the 252 residents who generously completed my questionnaire live in Springwood and other adversely affected areas of the Blue Mountains.

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41 Comments sorted by

  1. Felix MacNeill

    Environmental Manager

    Douglas, you suggest that one could, in principle, construct housing that was both energy efficient and fire resistant, which sounds great. However, given that simple solar passive design principles (lots of north facing windows to harvest winter sunshine, etc.) are probably the cheapest/easiest/most reliable component of designed energy efficiency, I wondered if these principles really are compatible with fire resistant design, which generally tends to suggest greatly reduced glass and seems to add an extra orientation problem of prefering to avoid facing predominant wind directions, which may or may not coincide with solar passive preferences...

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    1. Peter Ormonde
      Peter Ormonde is a Friend of The Conversation.

      Farmer

      In reply to Felix MacNeill

      Can still have glass Felix .. it's having an airtight house and insaulating/reflective screens you can put up when necessary that is far more important.

      We live in a very variable climate - likely to get moreso... we should start to think along the lines of having houses that themselves are variable - including being able to absolutely seal them up when required - but not necessary or desirable every day.

      I'm actually unsure that an 'architectural' approach is appropriate. .. too prissy…

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    2. Jeremy Culberg

      Electrical Asset Manager at Power Generation

      In reply to Felix MacNeill

      Fire resistance could be achieved through having shutters / panelling that can be placed over windows during periods of fire risk. Having solid fire resistant walls (at least one poster in one of the related stories suggested rammed earth) would also have excellent insulation values. Using natural breezes most of the time for cooling could be countered by having shutters as well.
      It should be possible to have materials and designs which are compatible with fire safety and energy efficiency - maybe…

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    3. Felix MacNeill

      Environmental Manager

      In reply to Jeremy Culberg

      Thanks Jeremy - I'm with you and Peter now - good insulation/sealing (sunlight and ventilation control) is a major mutual need for both sustainability and fire-resistance - I guess the key is mainly things like good external shutters - given that external awnings remain one of the better ways to keep unwanted sunlight out of a house, strong shutters might well serve a dual purpose.

      I wonder if the insurance companies mightn't be enticed to put a bit of financial muscle behind things like design competitions and help reduce the higher costs by offering serious discounts on policies.

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    4. Craig Read

      logged in via Twitter

      In reply to Felix MacNeill

      From my experience, strong northerly winds are a predominant factor in large bush fires in Victoria. I would expect the same thing in South Australia. So combining the two approaches would be difficult.

      I've often thought about what we'd build in place if it did burn down. If a fire started in the right spot with the right winds, almost every house in our street would. If it were possible, I'd be more inclined to dig in and build under-ground as people do in Coober Pedy. It'd be much warmer in winter, cooler and safer in summer. But with a slippage overlay at one end and an under-ground creek at the other, I don't think it'd be feasible on our block.

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    5. James Hill

      Industrial Designer

      In reply to Peter Ormonde

      "Australian Earth Covered Building" is a book written by The Baggs family of architects and published in 1986 by UNSW Press as a result of their professional efforts, combined with specific grant money.
      A seriously good book on the subject, possibly the world's best.
      It has recently been re-published, and is in most lending libraries.
      The major problem has always been lending authorities who baulk at the 40% higher cost found with earth covered or earth sheltered building, while ignoring the lifetime…

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    6. Lorna Jarrett

      PhD, science educator and science advocate

      In reply to Felix MacNeill

      Passive solar does not require "lots of north facing windows". I am far too lazy to dig up the references but off the top of my head the ratio of N-facing window to floor area is about 12%.

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  2. Mike Jubow

    forestry nurseryman

    Interesting article Douglas. In regards to timber on the exterior of a house, have you looked into the effectiveness of Boron fire retardants impregnated into the wood as a preventative? I have been looking at building a new house in a rural area and have looked at boron fire retardants but I don't know how effective they are. An old saw miller reckons that his dad used to use sawmill waste to boil 20 foot lengths of hardwood weather boards in a huge steel trough. The benefit he claimed was that…

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    1. Greg North

      Retired Engineer

      In reply to Mike Jubow

      Actually Mike, better than weatherboards are treated pine logs for not only is timber a great insulator, even better than brick veneer, treated timber as you refer to does not burn readily and will char.
      It may not be a great look having a charred house after a fire but still better than having no house.
      With a good generator/pump and secure storage, it would also not be too impracticable to run a stainless steel ring main right around the perimeter of your house at wall top height with sprays to have a water film running over all external walls and that might even limit charring.
      The other area that needs to be looked at is roofing for though most roofs will collapse once the building is alight, I am not too sure just how good a roof itself is and even the conducted/radiant heat inwards could possibly cause ignition, maybe a sloping concrete roof the answer.

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    2. Peter Ormonde
      Peter Ormonde is a Friend of The Conversation.

      Farmer

      In reply to Greg North

      Far be it from me to suggest anything might be wrong with your engineering Greg but I will anyway ...

      CCA treated pine anywhere is really not a good idea ... copper, chromium, arsenic is a tad toxic when it's burned ... you really wouldn't want to be living near charred CCA timber. You wouldn't want to be living anywhere that's been coated by the smoke either.

      Concrete is OK as a roof provided it has a nice steel mesh re-inforcing and is covered with a decent insulator like a solid layer…

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    3. Mike Jubow

      forestry nurseryman

      In reply to Greg North

      Greg, I presume you were suggesting treating pine logs with boron and not CCA? CCA still allows the wood to burn with the results that Peter Ormond describes. Using the pressure/vacuum method of treating pine logs with boron could have advantages as pine allows the chemical to be injected deep within the wood.

      Hardwood is difficult for deep injection due to the cellular structures of hardwoods but you can get an almost complete saturation of the sapwood which could be just as good but it would…

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    4. James Hill

      Industrial Designer

      In reply to Peter Ormonde

      Sales Engineer, perhaps?
      Not likely to be a member of the appropriate Institute.

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    5. Greg North

      Retired Engineer

      In reply to Peter Ormonde

      First off Peter,
      You still need a house that does not have combustible material right up to your walls and in deed the greater clearance you have the better.
      I have suggested in my own comment that secure water storage and pumping etc. is more than desirable to help keep any surfaces cooler.
      In ground storage will be better for securing you water system.
      I am not suggesting anyone plant a forest on a concrete roof so as you will have a fire on it and like any concrete structure, yes it does need to be designed and usually means having reo.
      What sort of farmer have you ever been?

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    6. Peter Ormonde
      Peter Ormonde is a Friend of The Conversation.

      Farmer

      In reply to Greg North

      Don't really want to argue about this Greg ... the physics is pretty straight forward ... but your suggestion of CCA logs was most incendiary.

      One of the most worrying features of this increasing intensity of wildfires is the amount of radiant heat ... enough to melt cars according to Phil Koperberg... that is blast furnace temperatures we're talking and I'm not sure anything at all will withstand that... so housing alone will not solve the problem.

      But living where I do - surrounded on three…

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    7. Greg North

      Retired Engineer

      In reply to Peter Ormonde

      Yes, don't argue Peter by using words that others do not, you referring to CCA and not me whereas I have said treated logs will be far better than weatherboards for they will be a better insulator unless of course you have weatherboards as thick as logs.
      But I agree even that compoarison is a bit irrelevant depending on other factors which I mentioned in my own posting, a bit copied for you.
      " It is certainly not rocket science Douglas and it is going to be more about whether people are prepared…

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    8. Peter Ormonde
      Peter Ormonde is a Friend of The Conversation.

      Farmer

      In reply to Greg North

      Greg, if you are going to talk about 'treated pine logs' then in the minds of 95% of one's readers you're talking about CCA ... since you didn't specify that you were actually talking only of some unspecified safer form of treatment one can only assume you were actually talking about CCA. You are mincing words.

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    9. Greg North

      Retired Engineer

      In reply to Peter Ormonde

      Peter, the dangers of CCA logs have been known of for many years and you'll find that most councils likely refrain from using them in public places because of the dangers.
      There are other treatments about that can include some fire proofing as Mike has referred to.
      You introduced CCA yourself so do not mince the words.

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    10. Peter Ormonde
      Peter Ormonde is a Friend of The Conversation.

      Farmer

      In reply to Peter Ormonde

      The reason I ask is that I'd be most interested in any treated pine arrangement that serves any useful purpose when confronted by 1000 degrees plus of radiant heat. What sort of chemistry we talking here Greg?

      It is one thing to be pretending some expertise in an area Mr North, it is another entirely to be throwing around rubbish notions that some gullible folks might actually think are valid or helpful... utter nonsense coming from a retired engineer remains utter nonsense but with a pretence of credibility it does not merit. You should know better.

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    11. Greg North

      Retired Engineer

      In reply to Peter Ormonde

      Have I said any treated pine arrangement is going to withstand 1000C and of course any material withstanding that will depend on the specification of the material and the duration of the heat, 1000C a temperature reading btw and not necessarily an indication of heat.
      Suffice for you Peter that I was not a chemical engineer and it is you who choose info and then declare that is what others have said that is rubbish, utter nonsense and continues your incredibility record.
      If you look at what I've said, it includes such caveats as
      " As for roof sprays and having the water and power, someone thinking seriously about protection ( rather than it'll never happen here ) should incorporate an in ground water storage and have a protected generator/pump unit but that will probably be of limited value depending on how close you have trees and what the house is built of. "

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    12. Greg North

      Retired Engineer

      In reply to Peter Ormonde

      Most engineers do study something of physics Peter and depending on your course even thermodynamics and then of course pre engineering course science and physics subjects explain the difference between temperatures and heat.
      The temperature of boiling water at sea level for instance being as you may know 100C whereas the heat required to do it will depend on various factors like the amount of water and heat loss during the process.

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    13. Peter Ormonde
      Peter Ormonde is a Friend of The Conversation.

      Farmer

      In reply to Greg North

      Yeeees? And this relates to radiant heat of 1,000 degrees C in what manner 'Mr North"?

      All the engineers I've ever worked with have been pretty damn good at physics actually... all of them without exception. Much much better than my grunting understanding of same ... but I can spot bulldust a mile off

      Seriously it's bad enough having to read your adventures in DIY homespun economix and your extraordinary gymnastics in your role as a LNP cheerleader ... but I would have expected you would…

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    14. Greg North

      Retired Engineer

      In reply to Peter Ormonde

      " Yeeees? And this relates to radiant heat of 1,000 degrees C in what manner 'Mr North"? "
      Perhaps you just spent far too much time grunting Peter to appreciate that whilst you will have temperatures within any generation of heat and indeed will need an ignition temperature to get a fire going and have radiant heat that will kill you or destroy structures, in all likelihood both will have happened well before a temperature of 1000C has been reached where you or the structure were, the extent of…

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    15. Peter Ormonde
      Peter Ormonde is a Friend of The Conversation.

      Farmer

      In reply to Greg North

      Does anybody still have any thoughts that this "Mr North" has any engineering background whatsoever? A phoney from top to bottom ..

      The Conversation is filling up with these conservative megaphones - all fakes - all claiming expertise and qualifications they lack the ability or opportunity to merit in real life. They have to pretend to be more than they are... it's a compulsion and it becomes very evident on closer examination that they are puffballs.

      Mostly they call themselves 'analysts". Strange creatures indeed and rather sad really... re-inventing themselves as what they could have been.

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  3. Paul Richards

    integral operating system

    Awareness is growing about berming, earth covered homes and benefits of fire protection.
    But these principles have been widely understood in our architectural community for many years. Most people don't even realise we have one of the world's best examples of an earth covered building.
    What better model could we possibly have for sustainable architecture and future vision?*
    The model with the most potential is the earthship, as this can be self sufficient and off the grid as the design principles prove. Very valuable assets in a fire prone area.
    ______________________________________________________
    *Parliament House, Parliament Drive, Canberra, Australian Capital Territory, Australia; *https://plus.google.com/110225028147014092158/about?gl=de&hl=en
    http://earthship.com/blogs/category/grand-central/australia/

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  4. Greg North

    Retired Engineer

    It is certainly not rocket science Douglas and it is going to be more about whether people are prepared to build something more like a concrete bunker than what most people have in their minds as a typical rural house.
    The picture with the caption " Houses could be built into the side of a hill. " is some sort of a compromise but living with a desert landscape out front is hardly the reason why people like to live in a forest.
    It may be that new style safer living sees a separation of house living…

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  5. Vince Moore

    Retired

    A bloke in Victoria designed, built and sold a house suitable for fire areas. The Ash Wednesday fires, so long ago, was the reason for the design. They are called RAL homes and I am not sure if they still exist but the idea was good. Amazing we are still going through the same thing after 40 years. What's the definition of insanity. "doing the same thing exactly the same way, hoping each time the outcome will be different, knowing it won't be."

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  6. John P Morgan

    Physics teacher (ret).

    After the "Ash Wednesday" disaster, the CSIRO built two demonstration homes at Cockatoo. We checked them out and my current home uses those ideas.
    There is no fuel around the building and the windows are fitted with external shutters. Outside the days of fire risk, these shutters hang on the wall near the relevant window and are quickly applied as needed.
    The role of radiation in destroying homes seems still to be not well understood.

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  7. Kenneth Mazzarol
    Kenneth Mazzarol is a Friend of The Conversation.

    Retired Auto Engineer and teacher

    Dome homes would be the answer but chest thumpers always seem go for angles, corners and aerodynamic slopes designed specifically to encourage a stiff breeze to lift the roof or provide a harbour for a nice fire to nestle in. Domes allow for plenty of individuality; size, colour, height, internal design, window and/or door placement, garden surround. They don't all have to look like little white igloos.

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  8. Geoff Clark

    Senior Lecturer at University of Tasmania, School of Architecture and Design

    I have been working as an architect for about 25 years. During this time in the building industry, I have seen common sense shoved unceremoniously aside in favour of legislated approaches to anything that happens to fall into the firing line. It is the nature of our society to legislate, and this, I think, is where it all goes off the rails; there is, now, nothing more uncommon than common sense.

    Possibly the most moronic amendment to the building legislation thus far is the introduction of the…

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    1. Andris Dinsbergs

      Web Designer/Developer, Artist at Loud Mountain

      In reply to Geoff Clark

      I concur with you Geoff completely. We are currently trying to get a CFA approved Bushfire Management Statement in order to gain approval for our Planning Permit for a block in the bush. This statement prepared by a specialist company relies on 'defendable space' and fuel loads etc. Who knows what expensive building materials we'll be forced to build with.

      These new provisions just seem ludicrous when you have 1000degrees of oxygen depleted fire ball coming towards you with radiant heat that can kill you from 200m away. A bunker solution is the only way to save lives as far as I see. Forget the house.

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    2. Alice Kelly
      Alice Kelly is a Friend of The Conversation.

      sole parent

      In reply to Geoff Clark

      Geoff, I'm interested in what you say because, one day my house could burn. If it does, I have the idea to build an underground house. I live at the top of a ridge and have planted non burning trees and lower shrubs which limit any wind from all direstion, and probably fire. The ridge lies above the house at the south, and I would want to build a long house facing north, which is not a prevailing wind. South, west and WNW winds are. I would make the house itself a bunker, with only the north facing front needing steel shutters. The house is already cut into the hill, and the faster front of a fire (slope) is at the south behind the ridge. I would not make a large house. I would cover the dirt roof with succulents. Is this feasible? In my experience the radiant heat is the most deadly aspect in the worst fires, and I would want to make something impregnable in this case. I agree with much you say, the regulation side I don't understand.

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    3. Mike Jubow

      forestry nurseryman

      In reply to Geoff Clark

      Geoff, as a suggestion, you could design a screen covering the frontage of a bunker house with a louvre system which consists of overlapping blades made of thin stainless steel, say about 2 mm thick with refractory tiles glued onto them so that when the louvres are closed there is only the refractory tiles exposed to the oncoming fireball. one thousand degrees is quite tolerable for refractory and there would be very little heat bleed-through.

      When there is no risk of fire, the louvres could remain open and the space between them and the house can be a comfortable patio. In fact, someone with your skills could possibly design a house that is clad all round with refractory and be able to keep a certain amount of aesthetics in the design.

      Maybe, the manufacturers of refractory tiles and bricks could make sheets of it that look like weather boards, clay bricks, logs or whatever design takes your fancy. And don't let your imagination stop there. What about roof sheeting too?

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    4. Geoff Clark

      Senior Lecturer at University of Tasmania, School of Architecture and Design

      In reply to Alice Kelly

      Alice, it sounds as though you have already made the first correct decision, that is, to use the ground as your protection. Some things simply work, and work simply.

      Of course I am going to take the easy-out and say that - yes, what you are thinking sounds feasible. Species selections will of course be climate / microclimate dependent and some homework would be required.

      As far as the building is concerned, specifics matter, it sounds as if your general approach is going to tick the main boxes…

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  9. Andrew Paterson

    Civil Engineer

    For the author, Douglas Brown:

    If you are researching the design of houses to withstand bushfires, I suggest you contact David Holmgren (co-originator of Permaculture) who developed such a design following the Ash Wednesday bushfires in Victoria.

    David documented his detailed recommendations in a booklet which I bought a copy of in 1993 called "The Flywire House - a case study in design against bushfire".

    He is a remarkable human being with great knowledge and experience of living within the constraints of Nature, and I expect has developed his ideas on fire resistant house design further since then.

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  10. Douglas Brown

    PhD candidate at University of Sydney

    A sincere thank you to those who have left a comment as part of this conversation. Be assured that I have read each one and value the insights given; they will help to inform this research field.

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  11. Ian Mannix

    Manager Emergency Broadcasting and Community Development, ABC Local radio

    The comment thread suggests that the outer covering of the walls is most important. That might not be the right place to focus.

    But before discussing that, perhaps we should give people an option that their home will be a refuge only long enough to withstand a catastrophic fire, say, 20 minutes? This would be more cost effective.

    It wont lead to a person having a home afterwards, but might be fewer deaths.

    Making a house "fire resistant" as opposed to "fire proof" will also include 30-50…

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  12. Lorna Jarrett

    PhD, science educator and science advocate

    A fascinating and important area of research - best wishes for your studies!

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  13. Warwick Rowell

    Permaculturist at Rowell Consulting Services

    I was not going to add to this thread, until I saw the comment a few minutes ago, and that the author of the article may still be connected.

    As always, a mix of irrelevant stuff and some pearls amongst them! Ad homs abound!

    No one has ever challenged me on being a permaculturist. sniff.

    I reckon it takes about ten lifetimes to be a good permaculturist, but David Holmgren is a good one.

    I recently applied for insurance for our house, and four refused to even quote, because postcode…

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