[GSBN] Straw Bale House Fire

[martin hammer]

David, Tom, and Derek,

Thanks for your additional descriptions of other straw bale (and related)
fires.  From these reports it's very clear that hot spots or smoldering in a
sb wall are NOT self-extinguishing as I postulated.  (Or at least one can
not count on them being so.)  And that Catherine and Pete did the right
thing.  (How could I suggest otherwise . . .?)

Thanks Derek for your drill-a-hole and inject-CO2 idea.  I think it has
great merit.  Within that idea, I think permanently dropping the temperature
of the hot spot is he most important thing.  Displacing the oxygen is great
for an indeterminate time, but I worry that oxygen could creep back into the
area, and the straw could re-ignite if the temperature was still high
enough.

Your idea also caused me to remember that Don Fisher (firefighter at the
CASBA conference) had concluded the best way to extinguish a fire in a sb
wall is to open a small hole at hot spots and inject water into them (I
forget how he said he would determine where the hot spots are).

Your method has the obvious advantage of avoiding water damage inside the
wall.  What seems ideal is a substance that cools the spot without water (or
other liquid) and which firefighters commonly have on their truck.  A very
desirable bonus would be a substance that displaces oxygen.

What follows are the 4 common types of fire extinguishers, including the
last one - Carbon Dioxide (bingo!) - although the others might be
considered, and nothwithstanding the fact that the CO2 description says they
are best for electrical and liquid fires.

DRY CHEMICAL extinguishers are usually rated for multiple purpose use. They
contain an extinguishing agent and use a compressed, non-flammable gas as a
propellant.

HALON extinguishers contain a gas that interrupts the chemical reaction that
takes place when fuels burn. These types of extinguishers are often used to
protect valuable electrical equipment since them leave no residue to clean
up. Halon extinguishers have a limited range, usually 4 to 6 feet. The
initial application of Halon should be made at the base of the fire, even
after the flames have been extinguished.

WATER extinguishers contain water and compressed gas and should only be used
on Class A (ordinary combustibles) fires.

CARBON DIOXIDE extinguishers are most effective on Class B and C (liquids
and electrical) fires. Since the gas disperses quickly, these extinguishers
are only effective from 3 to 8 feet. The carbon dioxide is stored as a
compressed liquid in the extinguisher; as it expands, it cools the
surrounding air. The cooling will often cause ice to form around the ³horn²
where the gas is expelled from the extinguisher. Since the fire could
re-ignite, continue to apply the agent even after the fire appears to be
out.

The question remains whether a CO2 extinguisher would sufficiently cool a
hot spot.  (The last sentence of the CO2 description is worth noting.)  The
simple answer is probably "it depends".  Finding the effectiveness and any
limits of this technique would be very valuable.


Martin


On 4/1/09 9:45 AM, "Derek Roff" <derek at unm.edu> wrote:

> David's story matches some others that I have heard, and is analogous
> to some things that I read years ago, about fires in the giant sawdust
> piles that used to exist at sawmills.  Smoldering fires could continue
> in these sawdust piles for years.  There was almost no oxygen, but
> there was enough to keep little fingers of combustion in the sawdust
> smoldering indefinitely, snaking their way through the piles.
> Disturbing the piles could cause dangerous flare-ups, just like we see
> when strawbale walls are broken open.
> 
> There is a story of a fire in a woodpile stacked outside, against a
> strawbale wall.  Catherine may remember the details.  The fire was
> extinguished, any remaining wood removed.  Something like ten days
> later, the owners noticed heat coming from the strawbale wall.  The
> fire had smoldered inside the wall for that time period.
> 
> All of this tells me that we can't count on bales being
> self-extinguishing, even when the plaster is intact.  Sometimes the
> fires may go out by themselves, sometimes not.  As others have been
> saying, we need to learn how to best fight fires in SB houses.
> Knocking down the walls is destructive and unsafe.  Putting lots of
> water into the wall is destructive and probably ineffective.  Going for
> the hot spots, found via IR measuring devices already described, seems
> like a good approach, but we need to learn more about how best to do
> that.
> 
> I have the beginnings of an idea that I would like to run by everyone
> for comment.  I'm thinking about situations like the wall fire that
> David described, or the end of Catherine's description, when all the
> visible part of the fire is out, and there is time to think and trace
> down the remaining hotspots inside the walls.  When the plaster is
> intact, the combustion inside a strawbale wall is borderline- just
> barely able to sustain itself, if at all.  If we locate a smoldering
> hot spot, and pull off the plaster in that area, we let in more oxygen.
> It seems to me that this could risk a flare-up of some sort, perhaps
> allowing the spread up to the next course or over to the next joint
> between bales.  In trying to clear out one smoldering hotspot, we might
> spawn another.  Is there a way to extinguish the hotspot before we
> remove the plaster?  I think there might be.
> 
> What I would like to test, is drilling a small hole in the plaster
> right below a hotspot.  Then, using a flexible tube to run a stream of
> CO2, or other inert, non-toxic gas, into the wall for a couple of
> minutes.  The gas coming out of a compressed gas cylinder becomes very
> cold, due to expansion.  I think we could decrease the percentage of
> oxygen present in the wall around the hotspot by a very significant
> amount.  I suspect that the combination of cold gas and less oxygen
> could extinguish the hotspot.  Perhaps we should keep the gas flowing
> while we remove the plaster over the hotspot.  This way, instead of
> oxygen rushing in, we could have CO2 flowing out through the hole that
> we are creating.  I imagine that this would make opening the hotspots
> safer, and decrease the chance of fire spreading inside the wall.
> Removing all the charred straw from the hotspot would be much safer, if
> all the smoldering was extinguished, and it was already cooled below
> ignition temperature, before we removed the plaster.
> 
> If testing showed that this approach is useful, it would be fairly easy
> and inexpensive for every SB homeowner to have a cylinder of CO2 on
> site for this purpose.  Perhaps a standard CO2 fire extinguisher could
> be made to serve in this process.  What do you think?
> 
> Derelict
> 
> Derek Roff
> Language Learning Center
> Ortega Hall 129, MSC03-2100
> University of New Mexico
> Albuquerque, NM 87131-0001
> 505/277-7368, fax 505/277-3885
> Internet: derek at unm.edu
> 
> 
> --On Wednesday, April 1, 2009 2:29 AM -0400 strawnet at aol.com wrote:
> 
>> Dear Martin, Don and everyone else,
>> 
>> Thanks for this information, Martin. I have a few thoughts and an
>> experience from a few years back that may add to the discussion,
>> particularly about whether there is a need to do anything about
>> smoldering bales within an unopened wall.
>> 
>> Back in the summer of 2003 we got a call from the fire chief of a
>> small town south of Tucson who had gotten a report of a very large
>> straw bale landscape wall that apparently had been burning for some
>> time, according to the owners of the house, who had been smelling
>> smoke for a couple of months and couldn't figure out where it was
>> coming from. The fire chief told me that they were planning to cut
>> open the wall and wanted to know if we wanted to come down and
>> witness what transpired. So the next day, Tony Novelli and I (and my
>> then 4 year old grandson Joe) drove down there with a video camera,
>> still camera, and our moisture meter for the great wall opening. The
>> fire chief said he would be bringing their infrared scope that would
>> let us see any hot spots in the wall.
>> 
>> What we found was amazing. The fire had apparently started at an
>> electrical box in the wall, which was subject to regular wetting from
>> landscape irrigation sprinklers. The wall was cool there but when we
>> took the cover plate off the box it was obvious that there had been
>> fire there. About twenty feet away, we found a hot spot and then
>> several others further away, indicating that the fire had been slowly
>> creeping along the wall for a great distance, moving so slowly
>> because there was very little oxygen available to support combustion.
>> Yet, there was enough to continue to burn for a long distance and
>> over a long time, even turning a corner and continuing on. Also, we
>> noted that much of the straw in the wall was fairly wet - we tested
>> it with our moisture meter. The heat from the slow fire was
>> apparently enough to dry the straw out. We opened all the places we
>> found hot spots and removed the smoldering straw - noting that
>> whenever we cut into the wall and exposed that smoldering straw there
>> was an increase in smoke though I don't remember seeing any actual
>> flames.
>> 
>> The lesson here is that straw is not necessarily self-extinguishing
>> and, as Catherine observed, the use of a non-contact thermal
>> measurement/imaging device, like those used by firefighters or energy
>> efficiency technicians can be invaluable in locating hot spots.
>> 
>> And, by the way, Joe had a fabulous day, the firefighters having
>> given him the full tour of the fire truck they came in and having
>> outfitted him with a fireman's helmut allowed him to drag the fire
>> hose from the truck to the wall and even let him spray a bit of
>> water! Tony and I had a good time too...
>> 
>> David Eisenberg
>> 
>> 
>> 
>> 
>> -----Original Message-----
>> From: martin hammer <mfhammer at pacbell.net>
>> To: (private, with public archives) Global Straw Building Network
>> <GSBN at greenbuilder.com>
>> Cc: Don Fisher <fishdl48843 at yahoo.com>
>> Sent: Tue, 31 Mar 2009 10:06 pm
>> Subject: Re: [GSBN] Straw Bale House Fire
>> 
>> 
>> 
>> Everyone,
>> 
>> 
>> 
>> Informative (and sometimes tragic) reports from everyone re: SB and
>> fire,
>> 
>> initiated by John Rehorn's alert about the recent fire in a SB house
>> in
>> 
>> Colorado.
>> 
>> 
>> 
>> I'm copying Don Fisher on this.  Don is a firefighter who gave a very
>> good
>> 
>> presentation at the 2008 CASBA conference on a SB house fire he
>> fought in
>> 
>> Arizona.  Everyone was glued to his presentation and it brought up
>> much
>> 
>> spirited discussion.  We learned from Don and vice-versa.  Don wrote
>> a piece
>> 
>> for publication in a fire-fighting periodical (Don, is there any way
>> I or
>> 
>> other GSBN members could obtain that article?) and gave subsequent
>> 
>> presentations to firefighters about fighting fires in SB buildings.  I
>> 
>> believe he also presented at the COSBA conference last year (is that
>> correct
>> 
>> John Rehorn?).
>> 
>> 
>> 
>> The biggest issue that came out of Don's interaction with the straw
>> bale
>> 
>> building community, is that protocols need to be developed, and
>> firefighters
>> 
>> need to be trained specifically about how to fight fires in SB
>> buildings if
>> 
>> they work in districts where they exist.  There is abundant evidence
>> that
>> 
>> plastered SB buildings are less of a fire hazard (more difficult to
>> ignite,
>> 
>> give more time to fight) than wood frame buildings, but treating them
>> like
>> 
>> wood frame buildings can cause additional fire and unnecessary damage
>> to the
>> 
>> building.  Maybe even an unnecessary total loss, or unnecessary
>> injury or
>> 
>> death of a fire-fighter or occupant.
>> 
>> 
>> 
>> Specifically I'm referring to the practice of opening a wall to
>> extinguish
>> 
>> evidence of smoldering or to wet and cool known or suspected hot
>> spots.  One
>> 
>> lesson Don learned in fighting the Arizona fire (Don, correct me if
>> I'm
>> 
>> wrong) was that opening a plastered straw bale wall at the site of a
>> fire is
>> 
>> usually unnecessary and counterproductive for the reasons we all know
>> 
>> (bringing oxygen and/or an ignition source to otherwise protected
>> straw, and
>> 
>> breaking tight bales into very flammable loose straw).
>> 
>> 
>> 
>> I'm intrigued by Catherine Wanek and Pete Fust's report about using a
>> 
>> non-contact heat sensing device to detect hot spots in the SB walls
>> after
>> 
>> the fire at their Black Range Lodge (and I thank the straw bale gods
>> it
>> 
>> didn't suffer more damage).  It seems like a great way to locate and
>> remove
>> 
>> heated/charred/smoldering(?) straw, while minimizing damage and
>> repair to
>> 
>> the wall system.  But I have to wonder what's wrong with doing
>> nothing to
>> 
>> the wall.  That is, how could it ignite if you don't give it oxygen?
>> And
>> 
>> eventually it will cool to a temperature where ignition is no longer a
>> 
>> concern, even if it were given oxygen.
>> 
>> 
>> 
>> Don, are there resources and do you think there is interest in the
>> 
>> fire-fighting community to develop protocols in partnership with
>> people from
>> 
>> the straw bale community, for fighting fires in straw bale buildings?
>> Also,
>> 
>> I can (presumably) forward to you other e-mails from this GSBN
>> discussion on
>> 
>> fire if you're interested.  Please respond to me
>> (mfhammer at pacbell.net) so I
>> 
>> know you've received this.
>> 
>> 
>> 
>> 
>> 
>> Martin Hammer
>> 
>> Berkeley, California
>> 
>> 
>> 
>> 
>> 
>> On 3/29/09 10:00 AM, "john rehorn" <rehorn at frontier.net> wrote:
>> 
>> 
>> 
>>> Hi Everyone,
>> 
>>> 
>> 
>>> There was a straw bale home fire on Friday near Lyons, Colorado.
>> 
>>> 
>> 
>>> http://www.denverpost.com/news/ci_12011181
>> 
>>> 
>> 
>>> I'm looking into the circumstances at present.  Sympathies and good
>> 
>>> thoughts to the Akia family.
>> 
>>> 
>> 
>>> With that said, I believe this can be an educational opportunity for
>> 
>>> all concerned.  How did the earthen plastered sb walls perform?  Why
>> 
>>> did the owner need to thaw out frozen pipes in March, especially in a
>> 
>>> straw bale?  There is also the need to correct erroneous assumptions
>> 
>>> regarding fire and sb as quickly and publicly as possible.  As you
>> 
>>> all know, one bad story about one straw bale house can overpower a
>> 
>>> thousand good ones.
>> 
>>> 
>> 
>>> Any information about this unfortunate event is very welcomed.  Also,
>> 
>>> if the subject of this house crops up on your internet presence,
>> 
>>> please educate the public in a good way.
>> 
>>> 
>> 
>>> Thanks,
>> 
>>> 
>> 
>>> John
>> 
>>> 
>> 
>>> John Rehorn
>> 
>>> Executive Director
>> 
>>> Colorado Straw Bale Association
>> 
>>> www.coloradostrawbale.org
>> 
>>> coloradostrawbale at yahoo.com
>> 
> 
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