[GSBN] SB Fire Fighting Article - plus a bit more

Mon May 4 05:43:05 UTC 2009

 Hello all,

We have long recommended that no straw be left exposed to cavities without at least a coat of earth plaster, clay slip, or some other plaster - for both fire safety and to reduce convective air movement through the bales into the cavities. Mud is great because it's inexpensive, easy to apply, available almost anywhere, and can potentially help with moisture control.

The Carswell fire in Tucson many years ago happened in a bale structure that was similarly furred out with steel framing with the bales unsealed to the cavities and the fire caused by welding, if memory serves. I think there was an article about this fire in The Last Straw. 

Whether the furring is on the interior for drywall or other sheet-type finish or on the exterior for a rainscreen or some other cladding system, it is important to not leave the bare straw exposed within the cavity. This might make a good subject for a graduate student thesis or disertation - doing fire tests of various systems - using different materials, clay slip sprayed on, the French dip method of pretreating bales with clay slip, a layer of earthen plaster, drywall compound, etc. - to see how the different treatments actually perform. Full-scale fire tests are very expensive but this is something that could be done at a smaller scale in a set of trials and then we might see if we can find more funding to do one or two full scale "official" tests to verify the performance of the best approaches. At the very least we could then 
speak from somewhat more than speculation about what works best and makes the most sense...a reasonable goal, methinks.

P.S. I'm writing this from Michal Vital's home in KarKur Israel after giving a talk to around 90 people in Tel Aviv last night. Tomorrow morning, Brad Lancaster, water harvesting/greywater/permaculture authority/enthusiast (if you know Brad you know that last term fits him well - check out his website if you don't know it already - www.harvestingrainwater.com), and I fly home from Amman back to Tucson, Arizona. We've been traveling in Jordan, Saudi Arabia and Israel since we arrived in Amman on April 14th. We left Tucson on the 13th. We were sponsored by the U.S. State Department as part of a cultural exchange program. They contacted Brad because they wanted a couple of speakers for a tour of Saudi Arabia for Earth Day to speak about rainwater harvesting and green building. Brad directed them to me for the green building part, we then asked to add Jordan to the trip, and eventually were able to extend our trip from the original 11 days to 3 weeks (only the first 11 days were included in the State Department part of the trip) in order to fit in visits to Petra, the Dana Nature Reserve in Jordan (and much more) as well as a trip to the Negev desert to Lotan and some water harvesting farms among many other things. We gave talks at many universities and other venues to faculty and students and engineers and met with all kinds of public oficials and other folks interested in the
se subjects. Some days we gave 3 and one day, four presentations in addition to meetings and tours. We haven't tallied it up yet but we're pretty sure we gave well over twenty presentations each in the past three weeks. It was a whirlwind and the last week plus, after we were done with the official State Department part of the trip has been almost as full, but we have had the flexibility and control of schedule (and only a few presentations) unlike the first part. Both have been extraordinary and Brad and I will be writing and sharing info about this over the next few weeks (and longer of course). I had a little side trip of a couple of days stay in an Amman hospital after getting sick on the flight from Jeddah back to Amman on the 23rd (thanks to an unfriendly amoeba I picked up somewhere) but am nearly back to normal after taking my meds for that and following recommendations about food and drink...Brad was slowed down by something less serious at the same time so though it messed up our schedule (and things planned for our Lotan visit - so sorry Alex and all!) it also gave us a much needed rest in the middle of the trip - though there are better ways to accomplish that...

Overall, this has been a most excellent three week adventure with a great traveling companion! Much learned, much shared, much yet to ponder and process and unfold... We are hugely grateful to so many people all along the way!

Yeeehaaa! 

David Eisenberg 

-----Original Message-----

From: Laura Bartels <laura at greenweaverinc.com>
To: (private, with public archives) Global Straw Building Network <GSBN at greenbuilder.com>
Sent: Sun, 3 May 2009 7:18 pm
Subject: Re: [GSBN] SB Fire Fighting Article

Martin and all,

Last summer I had the privilege to go to Alaska to speak for the Alaskan Intertribal Council about sustainable housing, and while there got to spend a day at the Cold Climate Housing Research Center in Fairbanks (if you ever get a chance to check their website or better, make a visit, don't pass it up). Of course, I tried to see as many straw bale houses as I could, and as it turned out, had to chance to stay in one as well. Every home I saw, but not every home I learned about, was furred and drywalled on the interior and furred and sided on the exterior or sheathed and stuccoed with acylic. The home I stayed in had a vapor barrier directly on the straw, sealed top and bottom and at joints, steel studs, fiberglass in the cavities (added after they found convective air movement) and drywall. In talking with the owner, the main reason for this in likely all the cases was their short season and lack of knowledge about plastering. He admitted that he would prefer to go back and plaster now that he knows more. 

Fire was certainly on my mind as I toured. The extremes of temperature and moisture drive seemed to be not affecting the integrity of the straw in the home I stayed in, as it had a monitoring system. 

One home closer to southeast AK had used St. Astier lime. The owner of that home had built a test structure with moisture monitoring prior to building his home. 

I also know of two homes in my area that are drywalled.

Perhaps this is another area, like parapet walls, that requires a stronger education campaign. 

Best,

Laura

Laura Bartels
P.O. Box 912, Carbondale, CO 81623
Ph 970-379-6779, Fax 970-963-0905
laura at greenweaverinc.com
www.greenweaverinc.com

On May 3, 2009, at 7:52 PM, martin hammer wrote:

 G ‘ day John,

 In the article it says - “The owner . . .said he was soldering in that area and that there was fire in the wall under the sink.”  

 So I believe it started from a soldering torch, but I don’t know what first ignited (cabinet, drywall paper, straw, wood furring, . .).  My best guess is that regardless of what ignited initially, the fire was quickly inside one of the furred-out cavities between the drywall and the bales, and then shot up to the roof framing where the fire spread and caused the most damage.

 The article does suggest the reason for the cavities (foolish, of course), which is the owner wanted a smooth, straight drywall finish on the interior, and installing wood furring strips on the bales to provide attachment for the drywall seemed sensible.  They didn’t realize they were creating a fire hazard.  They of course20could have achieved a smooth, straight plaster finish but they might not have thought this was possible (or was too expensive).  All of us would consider drywall over straw bale a kind of blasphemy, but that’s what they chose to do.

 And yes, the observation you mentioned is a flawed one (among others).  My comment (rebuttal) that I sent to Don Fisher is shown in blue in your e-mail below.

 Thanks.

 Martin

 On 5/3/09 4:32 PM, "John Glassford" <jacksflat at gmail.com> wrote:

G ' day Martin

 Thanks for that article most interesting and informative.

 The article does not say how the fire started in the first place any clues?

 Reading this article it appears that the fire may have started in the roof or at the kitchen sink and travelled into the roof?  Also I do not understand why any builder would create a straw bale wall that has cavities, makes no sense.  See an extract below from the article:

 "The results of the recon with the thermal imaging camera {TIC} indicated that fire was in approximately 75 percent of the attic and that fire was traveling downward through the straw-filled walls in about 50 percent of the house. It was later determined that the top of the walls had no drywall on the top plate and that there was a space between the straw and the inside and outside wall. This flaw in construction contributed to the total loss of the building.

 Because of the high winds and the exposed OSB roof decki
ng, the 5,000-square-foot building’s attic was almost totally involved. This caused the top of the unprotected straw bales to ignite from embers and burning materials that fell into the void between the bales and the interior and exterior walls. You could see fire with the TIC on the outside walls on the top of the bales and on the bottom of the bales; there was no fire in the middle of the wall."

 Not sure about the following observations:

 "The problem is that straw, like the blown treated paper insulation, is combustible. Both will burn when temperatures reach 1,200°F. 
 (I think this unfairly targets straw bale, because in addition to the fact that (as you say) straw and blown treated paper insulation will burn when temperatures reach 1200 F, so will wood, and other wood products like plywood (correct me if I’m wrong about this).  And actually, straw bale (when plaster is directly applied to it) is less prone to combustion than wood frame  because there is less air and fewer or no chimney spaces to facilitate combustion.) To combat this, the straw stacks were designed to be treated with fire retardant and covered airtight with an exterior covering. In this case, a modification was made for aesthetic reasons."  (The bales may have been treated with a fire retardant in this case (borate?), but we generally do not considered it necessary. The airtight exterior covering generally IS considered necessary, and I’m glad you pointed out this very important design (
or construction) flaw in the AZ building.)

 Thanks again Martin.

 Kind regards
 The Straw Wolf
 Huff 'n' Puff Constructions

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