[GSBN] SB Fire Fighting Article

Mon May 4 02:18:26 UTC 2009

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 course could 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 decking, 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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