Straw Bale Homes Protect Against Fire Where Conventional Homes Fail

house-fire.jpgWe have all seen images of the massive fires in Southern California. I would first like to send out my sympathy to anyone affected by the flames. I would also like to send out my respect and gratitude for the firefighters who risk their lives and give their all to defend the homes and lives of others. I have considered how to write about this topic over the last few days and I want to be clear that my intention is to support home owners in the affected areas, not judge them or tell them they have “done something wrong.” I want them to know about the incredible fire resistance of straw bale construction and how they can rebuild their homes with security built in. I have included a video at the end of this post which speaks to the fire wall testing data for straw bale walls.

Protecting against fires has long been important to code officials, builders, and home owners alike. None of us want to see our homes go up in flames. None of us want to experience the loss and the grief associated with that loss. Building codes exist to protect homeowners from fires: both minor and catastrophic. Even with those codes in place, we have seen that a well built house can burn to the ground in a matter of minutes. To me, the reason for this is obvious. A conventional stick framed home is nothing more than a series of chimneys behind a thin layer of fire protection. What many homeowners don’t know is that the majority of the fire protection required by code in a conventional home is in the form of drywall. That’s it! 1/2″ of gypsum board is all that is required to protect you from fire. Once that drywall barrier has been compromised, there is nothing to stop the fire from attacking the structural wood and/or steel framing in your home.
burnt-house.jpg
Straw bale homes are different. Straw bale houses are known for and have been tested to resist fire by up to three times that of conventional homes. Three times the protection may be the difference between a total loss and a miracle. The photo below shows how a home built of the right materials can survive even amongst completely destroyed homes built to conventional standards. I want to be clear that this photo is not of a straw bale home as I do not have a photo in my possession that shows what I am talking about; however, the data is the same. A house built with bales has up to three times the fire resistance of a conventionally framed house. The house in the following photo does have one thing in common with straw bale homes: it is plastered. This is the first line of defense for straw bale homes. The 1- 1/4″ of plaster provides far superior resistance to flame than most sidings. Imagine trying to burn your way through that much plaster.
fire_resistance.gif
The second, and often most surprising element of straw bales that increases the fire resistance is the bales themselves. When most people think about straw and how it performs in fire, they think about barn fires, spontaneous combustion, and other fire stories. The fact of the matter is that barn fires are caused by hay that was baled too early with high levels of moisture still in the crop. The fires start when that moisture creates heat by decomposing the hay and then the hay flares from the heat of the decomposition inside the bale. Straw is baled when the crop is dead and dry, usually around 8% moisture content by volume, so no interior decomposition occurs. Moreover, the bales are so tight, that most of the oxygen has been squeezed out of them. Fire cannot exist without oxygen, so once again the bales have created a form of protection against flame spread. Consider that a bale is like a phone book. If you rip out the pages one by one and light them on fire, they will burn: so will loose straw (although not very well due to the high silica content). If you hold a lighter under the entire phone book, however, you will likely run out of fuel in the lighter before the book catches fire because there is no oxygen in between the pages to support the flame. The same is true for the baled straw. Now put the two systems together: thick plaster on both sides of the wall and dense, oxygen deprived bales inside. This combination makes for a very resistant wall and one which has a much better chance of survival in fire situations. Protecting your home from fire in other ways is still important. Be sure to clear brush from around your house, clean out your gutters and under your decks, and so on. There are several sites which offer guidance on how to protect yourself from wildfires. If you live in a fire prone area, I strongly recommend that you complete the steps outlined on those sites.

The above video talks about some relatively recent fire testing on straw bale walls. The results of the testing were very positive and support everything that I have said about straw bale walls and their fire resistance. My want is for people who live in fire prone areas to start getting serious about protecting themselves from fire. Thousands of homes and buildings have been destroyed in the last two weeks by the wild fires in Southern California. Most of the people who lost their homes will rebuild. I challenge them to build with bales instead of building another conventional home. The benefits go beyond fire protection and reach into the world of green construction and healthy homes. But for this conversation, consider the difference between a total loss and a miracle the next time the fires comes blowing through…which they will!

28 Responses to Straw Bale Homes Protect Against Fire Where Conventional Homes Fail

  1. Steven Holt Fri, October 26, 2007 at 1:41 pm #

    One area that is not covered by this post is how to protect the extensive often wooden overhangs that are also a feature of most straw bale construction. Yes, this is nitpicking but it is not meant in any way to negate this fine and constructive post. This is a particular concern I have not personally found any good way to address in my own straw bale construction projects in a potential forest fire zone.

  2. Tony Novelli Fri, October 26, 2007 at 4:18 pm #

    For those looking for the actual testing data, the engineers report and the video of the fire testing referred to here, please go to: http://www.ecobuildnetwork.org/strawbale.htm and help support Ecobuildnetwork. They have done more to provide technical support for bale building than anyone around.

    All best,
    Tony Novelli
    Assistant Director
    Development Center for Appropriate Technology

  3. Andrew
    Andrew Fri, October 26, 2007 at 4:29 pm #

    Steven,
    You raise a great point. The weakest part of straw bale homes in terms of fire is indeed the areas of wood, the large overhangs being perhaps the most at risk. One way to counter this is to stucco the soffits of the overhang. This gives a stronger fire resistance to the overhangs. You can also consider using a hardiboard (cement board) siding material on the soffits. The biggest thing in this situation is to remember to clear the brush away from the house. If the flames cannot wick up under the eaves, you will be considerably safer than if you have trees or brush too close to the house. That is not to say that trees around your house are a bad idea. In fact, they are crucial to natural cooling of the home; however, they should be well limbed up so that any low ground fires cannot “ladder up” into the tree canopy and ultimately into the overhang areas.

  4. Nancy Hyden Woodward Fri, October 26, 2007 at 4:43 pm #

    I’m very glad you posted this topic because I was about to write you on another matter. How well do you think straw bale houses can stand up to coastal living,as on the South Fork of Long Island (home of “the Hamptons”) with fog, humidity, sea breezes and winds and the occasional hurricane?

    Here, we are “famous” for shingle houses and McMansions, with little available real estate available to the average person unless the land is 1/2 or 1/4-acre. My town really put the squeeze on locals when it up zoned to 5 acres minimum, two years ago.

    Do these straw bale houses have any leverage, cost wise, to ranch or other modest type houses that a local could build?

  5. Andrew
    Andrew Fri, October 26, 2007 at 5:46 pm #

    Tony,
    Thank you for posting this. We used to have a link to EcoBuildNetwork on our old site and we have not yet uploaded the link on this new version of the site. Thank you for bringing this up. It is true that the folks there have done so much for straw bale and research therein.

  6. Andrew
    Andrew Fri, October 26, 2007 at 5:56 pm #

    Nancy,
    Thanks for your question. Straw bale construction fares really well in most climates. It can be suitable for coastal climates as long as the humidity is under control. you may want to consider using a house de-humidifier if you are concerned about humidity. Another thing to pay attention to is the mesh you use in over the bales. If you are in coastal areas, be sure the mesh is galvanized or it will rust and show up in the plaster. Yuck! Cost wise, straw bale homes are more expensive to build than conventional (contractor based numbers) but you reap the benefits for years to come which ultimately make them less expensive in the long run.

  7. Cadmon Whitty Fri, October 26, 2007 at 6:23 pm #

    Mr. Morrison,

    I am a straw bale contractor living in New Mexico; I have specialized in straw bale houses and walls for approximately 16 years and own a company called Paja Construction, Inc. I’ve built scores of straw bale houses and hundreds of straw bale privacy walls.

    I just read your article about straw bale houses and fire. Based on my unfortunate experiences with the same, I must say that in my opinion you are somewhat inaccurate about the burnability of straw bale houses. Yes, it is true that lab tests and some field situations conclusively prove the inherent safety of bales when it comes to burning them. However, there are numerous factors which will allow a straw bale house to easily burn. For example, a house I was constructing burned down when a plumber sweated some copper pipes against the bales during a fierce wind storm—and believe me, with the wind blowing a steady supply of oxygen against those bales, they burned like torches all the way through. Another factor for burnability of a plastered straw bale structure is whether there’s a supply of fuel (such as grass or wood or a propane tank) close to the straw/stucco which would allow the fire to continue burning against the stucco until the stucco fails—and if the stucco was not applied very thickly, it will fail remarkably fast and thus expose the bales to the fire. Once fire gets into a structure, even one that has been stuccoed, it will smoulder/burn pretty well indefinitely and becomes extremely difficult to extinguish. Again, I’m talking from personal experience. Not least, if the eaves of a house are wooden, the fire will readily enter via the roof especially if there is a wind blowing—which in the case of the recent California fires there certainly was.

    In short, and in fairness to people on your blog, I think you should modify your latest statements.

    Sincerely,

    Cadmon Whitty

  8. Andrew
    Andrew Fri, October 26, 2007 at 7:08 pm #

    Cadmon,
    Thank you for your perspective on this topic. I appreciate you taking the time to write to me about it. that said, I think that the scenarios you have experienced do not lessen the effectiveness of straw bales at resisting fire. For example, if a plumber was careless enough to use his torch near bales, he would probably be careless enough to do the same around loose insulation of other flammable materials. The idea of a propane tank near a house causing fire damage would obviously have an affect on a conventional house as well. The eaves of the house are again an issue in any home, not specific to bale construction. I get your point around the risk of fire in any home. One basic need is for the contractor to have several fire extinguishers on site during construction. Bale houses are certainly more at risk for fire when they are unplastered and so that is the time that extreme care must be taken. Beyond that, it sounds like you have had some unfortunate experiences with fire and bales. Again, i do not think this negates the testing or the majority of field experience out there. Thanks again for the point of view. I appreciate the different opinion.

  9. Mark Frazier Fri, October 26, 2007 at 9:13 pm #

    Andrew,

    The house in your picture which survived the SF fires is made of AAC (Autoclaved Aerated Concrete). We actually looked into using it as an alternative, but were told (in earthquake land) “You couldn’t afford the structural engineering”.

    Also, it doesn’t really matter much when the city is forcing us to put in $8,000 worth of fire sprinklers in the house. It won’t burn, but it will probably be ruined by water….

  10. Andrew
    Andrew Fri, October 26, 2007 at 9:23 pm #

    Mark,
    Yeah. I knew the house was a concrete product, but it was such a great photo and I thought it represented the point well. $8000!? Wow. That’s insane. I guess I see why though these days on the news. I hope you can get the home you want with so much expense in the fire proofing. I guess it will be worth it in the long run.

  11. abraham Kryger Fri, October 26, 2007 at 9:30 pm #

    I am building a straw bale house in Carmel Valley, California and have covered a few areas of the bales with OSB plywood by the doors and windows to create a smooth surface. There are studs on either side of the wall.

    The rest of the bales will be covered with wire and plaster. Do I have to do anything to the bales that are simply covered with OSB , which will then be covered with stucco wire and plaster but thinner coat than the 1.5″ over the bales. I wanted to ask if it is necessary to cover the bales in those areas where plywood is put in front of the bales. These areas will be enclosed. Do they have to have stuffing of extra straw? Cover with paper? Cover with wire? Or can they be left and covered with plywood and then stucco paper and wire and plaster? Thanks. AK.

  12. Alain Saffel Fri, October 26, 2007 at 10:12 pm #

    One other aspect that seems to have been missed is the roofing material itself. I recently moved from B.C. where in 2003 we also had a large number of houses burned in forest fires. Cedar shingle roofs proved to be the Achilles heel for a number of homes. I’m not sure how many of the houses in California were built that way.

    The advancing firestorm sends out swarms of large embers that land on the roof and begin to catch the roofing material on fire. I don’t know how susceptible to fire asphalt shingles are, but I suspect it’s probably not good.

    I recently attended a home show where I saw a number of alternatives to traditional roofing materials that might work better. You could use slate, metal, concrete tiles and even rubber tiles(apparently it is fire resistant.) California also has a lot of houses with terracotta tiles.

    I moved to Alberta and just north of me in Edmonton there was a major fire that wiped out many closely spaced houses. The reason the fire spread so quickly there was that all the houses had vinyl siding.

  13. Alicia Scott. Sat, October 27, 2007 at 7:00 am #

    Dear Mr. Morrison:
    I was thinking the exact same idea about the fire resistance! I am a sixty year old widow, my only daughter got married on December , 2006 with a Navy young man despite his age (25) he already went twice to Iraq! and now he is studying to be a Chaplain; she is pregnant with
    TWIN BOYS! My life is full of surprises! Anyways…I got a dream, for many years (about 15) since I took a look in a picture of a Straw Bale house…I see so many good things and even I did not get inside of any of them, I can feel them! I was planing to build a model retirement center, as we grow older, our system cannot tolerate many allergens, and we know that in the traditional construction we have thousands of them. But my husband passed away on February of this year and many other things took priority, including our daughter’s pregnancy. However, my dream still alive and some day I know will be a reality. The fires here in California are the perfect opportunity to show the advantages of Straw Bale construction, focusing not only in the homeowners, but also Insurance Companies and Authorities. I do not know how much difference would be if the houses that burned were build with straw bales instead of traditionally. I heard somebody saying that because of the intense heat the houses burned of spontaneous combustion.

    Mr. Morrison: I admire you because you are promoting this type of much healthier way of living, I wish you the best success and if I can help in any way, please just let me know. My name is Alicia Scott my Grandparents were from Italy and I born in Argentina, I am a Tax Professional and a Notary Public. I speak Spanish college level and also do translations, transcriptions and interpretations in Court.

    Blessings, Alicia.

  14. Andrew
    Andrew Sat, October 27, 2007 at 12:27 pm #

    Abraham,
    The bales should be covered with a layer of clay slip or something else to protect against fire. You can use slip or plaster or some other type of material to isolate the bales from possible flame spread. Other than that, they do not require any special attention unless the areas that are covered are large. If they are, you will need to consider how moisture will escape the plywood. A thin ventilation layer would be needed to allow moisture laden air to drop into the gravel at the base of the walls rather than condense against the plywood. Finally, you will have to figure a way to secure the bales to the wall. You can drill small holes in the plywood and run your twine through them before you stack the bales and then use that twine to sew the bales to the wall assembly. You can also use plaster lath at the top of each course and dowel it to the bales from the top down and then bend it up and staple it to the inside of the plywood. This second method is good if you don’t want to penetrate the plywood. I hope this all helps.

  15. Whitedove Sun, October 28, 2007 at 2:28 pm #

    I just moved back to Florida. I think we made a mistake and are going back to Tucson, AZ where I first saw a straw bale house and love it so much. Do you know of any one in the Tucson area that makes them and can you get me a number. I hate the damp, humidity here and I have pain Ii didn’t have as bad in Arizona. I believe a straw bale wouldn’t be too damp, or can you build here in Florida? I hate to leave kids and grand babies but health is important, thank you Whitedove

  16. Andrew
    Andrew Mon, October 29, 2007 at 10:54 am #

    Whitedove,
    The humidity in Florida makes it difficult to build with bales, but not impossible. Depending on where you are and how humid it is, you may be able to get away with installing a house de-humidifier to keep the bales dry. This is somewhat experimental at this point, but I think it is possible. If you were to decide to go forward with this, I would suggest you build a small structure and test it for a year or two with permanent moisture content sensors built into the walls. If they read okay over time, you could continue with the construction of your home. You might also want to email this person who has a small bale home in Pace, Florida. They may be able to give you some feedback. Here’s the address: strawboss94@juno.com.
    If, on the other hand, you decide to go back to Arizona, there are many bale homes there that have stood the test of time. The weather in Tucson is perfect for bale construction. There is (or will be soon) a list of builders, designers, and more in Arizona on our Green Building Resource Center (http://www.strawbale.com/green-building-resources) that can help you with bale construction. If you don’t see what you need yet, please visit again in a few weeks as we continue to add resources week by week. It is a long, arduous process, so please be patient as we add the details. In the meantime, you can also visit the resource center and click on any of the supplied links to other Google sites that may have a direct source for you. Good luck and stay tuned.

  17. Keith Mon, October 29, 2007 at 4:12 pm #

    You state the the info will be released in July 2006. Did you mean 2008 or is this an old video?

  18. Jacquelyn Mon, October 29, 2007 at 5:16 pm #

    Hi Andrew,
    I bought your dvd’s and have been very interested in straw bale construction for many years now. We live on a ranch outside of Ensenada B.C Mex. and on oct 26th 2003 our house and bakery burned down to the ground (Santa Ana winds). We just barely made it out alive (8 of us) except for my grandma, she died in the car while we were escaping (smoke inhalation). Since then we have been slowly rebuilding and just the other day got another scare. I WILL NOT lose everything again. I’m seriously considering finishing my house with straw bales(the other half is brick) but am so unconfident and scared of messing the whole thing up. Do you think it is a task a novice can do?
    My husband is a pianist and knows less about constrution that I do. I do understand the dvd’s but am still nervous.
    Do you give hands on courses in this area? I want to finish my house before the next fire beats me to it!

  19. Andrew
    Andrew Mon, October 29, 2007 at 7:11 pm #

    You are correct Keith. This is an older video. Sorry to not have mentioned that when I put the blog out. If you read the comments you will find the link to the actual data from the study. Thanks for pointing this out Keith.

  20. Andrew
    Andrew Tue, October 30, 2007 at 6:40 am #

    Jacquelyn,
    I am sorry to hear about the loss of your home and more importantly your grandmother. I am also happy for the safety of the rest of your family. The house can be rebuilt, so saving the family is everything. I truly believe you can build the home you want. I can offer you support in the form of consulting and/or a workshop. I do not currently have plans to do a workshop in your area, but I would be happy to consider it if you want to host one. You and I can talk more about this on email if you are interested. The bottom line is that I do believe you can build the straw bale home you want and I know I can help you in some capacity.

  21. Megan Garrett Tue, October 30, 2007 at 7:19 am #

    Dear Andrew Morrison,

    A Canadian builder, Louis Gagné, got the Canadian Mortgage and Housing Corporation (CMHC) to do fire testing on straw bale houses some years ago. Unfortunately I do not have the exact reference to give you, but I do remember that the test included applied heat of about 1800 degrees F (about 1100C), and that in some 3 hours’ of application, the bales did not burn, and the inner temperature changed only some 60C (or so – sorry I can’t be more precise). If I find the reference, I’ll send it you ( a search didn’t turn it up, but I have a paper copy here – somewhere).

    Louis Gagné’s method is somewhat different from yours: he encases each bale, leached, in mortar, creating enormous, independent “bricks”. When I come to build, I think that it is the method I will choose.

    Cheers!

    Megan
    Montréal, Québec

  22. Andrew
    Andrew Tue, October 30, 2007 at 7:33 am #

    Thanks for this information Megan. I hope you are able to locate the source of the study and provide us with a link to the data. That would be great.

    Andrew

  23. Piet Sat, November 3, 2007 at 2:11 am #

    Hi Andrew
    Have a look here http://www.compaillons.fr/celles_sur_belle1.html
    This “ARCANNE” is involved in safety, buildingcodes, insurance and more in the JURA in France and did the firetest on bales in lab conditions for roof and walls. Temperatures of 900°C on the outside for more than one hour and only after more than 40 minutes there was a slow smoldering inside the bales started!
    Only bricks or cement do better

    Piet
    Netherlands

  24. R. J. Humpal, JD Thu, November 8, 2007 at 7:04 pm #

    Great information! I am designing several homes for a project here in Southern California. I am using cargo containers for the structure, with strawbales and a new foam material for the insulation. I want the homes to be as fire safe as one can get. Using the containers for structure gives me a house that is termite, fire, earthquake and windstorm safe. I would like to have others who have tried this to comment. Thanks, Dr. Rich

  25. Leroy Sun, November 11, 2007 at 7:56 am #

    Andrew, and others,
    My wife and I recently (April, 2007) completed our straw bale home south of Hot Springs, S.D. We live in Wyoming, so it was really just a get away place for us, and several of our friends. On July 7th there was a lightening strike in the canyon to the southwest of our property. The local firefighters were unable to fight the original fire because of its location, and opted to wait until it came up out of the canyon and try to contain it. When the fire erupted out of the canyon several hours later it was a virtual tornado of fiery destruction. The path it took over the next 24 hours was more typical of a tornado than a conventional fire. It spared some homes, and completly destroyed others within minutes. Eyewitness accounts tell of the approaching flames spontaniously combusting houses in their path, leaving only smoking foundations in their wake. No house managed to survive a direct assault by the fire. Most were consumed within moments. While our house was destroyed in the fire, it survived for more than 14 hours. Our stucco exterior was complemented with a steel roof, facias, and soffits. The surrounding trees had been pruned up, all brush had been removed from the site, and all the surrounding trees had been thinned. I have determined that the house burned from the inside out. The furniture, cabinets, interior wood work, post and beam structure, second floor framing, stairs, roof framing, and all the interior partitions burned out….completly, leaving only ash behind. Once the framework burned sufficently to allow the roof to collapse, the walls came down with it and then the straw smouldered, tho never was burned and consumed.
    I am convinced that had the fire department been able to get to the house, after the flame wall had passed, they could have put out the interior fire, and the house would be standing today.
    All in all I was quite proud of the way the house stood up to the fire, and I am in the process of using the insurance money to build another straw bale house here in Wyoming. What a totally awesome technology. I would highly recommend it to anyone.
    Andrew, keep up your good work. The planet needs it.
    Leroy

  26. Andrew
    Andrew Mon, November 12, 2007 at 12:38 pm #

    What an awesome story. I am sorry for the loss, obviously, but what a great tale to tell about the power of straw bale walls against fire. Thank you for sharing this with us all.

    Andrew

  27. Alain Saffel Thu, December 13, 2007 at 7:38 pm #

    Leroy,

    Sorry to hear about your house burning down. It’s surprising that it did.

    One thing I wondered is if you had aluminum or steel roll shutters to protect your windows and doors? These are becoming more and more common on houses as anti-theft devices (businesses too) and I wonder if that might have helped to protect your house further.

    If the fire spontaneously combusted the materials inside your home, perhaps that might have been enough protection to help stop it? I’m not sure, but it’s an idea.

    When I eventually build my house, I’d like to install them anyway.

    Good luck on your next straw bale house!

    Alain

  28. Scott Young Thu, August 28, 2008 at 11:04 am #

    Leroy,

    I just purchased some land near Evanston, Wyoming. Since you indicated you are building a stawbale in Wyoming, I would be interested in learning more about any code issues you have encountered and whether you are building the house yourself or having it contracted. Thanks!

Leave a Reply