[GSBN] FASBA Fire test 8th January 2014: 8mm Lime plastered straw infill wall successful >90min

[Derek Stearns Roff]

Great news on the fire test.  Congratulations and thanks.

Regarding the risk of carbon monoxide from burning straw, certainly we should all be aware of it.  But I think we should also put this risk in proper perspective and context.  As the fire tests have shown, you can't get a strawbale wall to burn in this way, unless you have a big fire outside of the wall, directing a lot of heat at the wall for a prolonged time.  Conventional house fires create toxic atmospheres and severe amounts of carbon monoxide long before they generate the amount of heat used in these tests.  The atmosphere inside a briskly burning house is already so toxic, that I doubt whether the strawbale wall makes a meaningful contribution, in most of the likely scenarios.

On the other hand, fires in strawbale houses raise two other significant concerns, which have been discussed here before.  One is that firefighters have not been trained in fighting fires in strawbale houses, and in some documented cases, have used techniques that increased risks to adjacent structures and to the firefighters themselves, as well as causing or hastening the complete destruction of the building.  When firefighters choose to knock down all the walls of a burning strawbale building, they greatly increase the available fuel for the fire, which doesn't happen with most other kinds of construction.  In addition, all super-insulated houses contain a lot of heat from a fire inside the house, which can raise the internal temperatures substantially above those attained in fires occurring in conventionally built houses.  As super-insulated homes become more common, I hope that firefighters will come up with safer and more effective ways of dealing with fires in these kinds of structures.

Derek


On Jan 29, 2014, at 5:21 AM, Frank Tettemer wrote:

Compliments from Canada, to you and your team, Dirk.
Yes, that is some good news to share,
My one-sided-thinking has always put straw bales up on a pedestal, when considering their burning emissions to the emissions apparent from burning polyisocyanurate foil-backed foam, vynyl siding,or EPX foam. That comparison seems to have obvious results.

I had never thought to consider the emission of carbon monoxide, as a result of the incomplete combustion of the straw. A headache is a very visceral response. That is a very good awareness.

Frank Tettemer
Living Sol ~ Building and Design
www.livingsol.com<http://www.livingsol.com>
613 756 3884


On 28/01/2014 11:12 AM, Dirk Scharmer wrote:
I sent this mail on 9th of January but I didn't get it via the list by myself, so I'm afraid, it didn't go through, or did anyone of you already receive it?

Something to share:
Yesterday FASBA- Germany tested a straw insulated timber frame wall plastered on both sides with "lightened" lime plaster (graefix 73 pajalith declared to be 8mm thick), successful over 90 min according to DIN EN 1365-1 : 1999-10. Some weeks ago, we had an unsuccessful test of the same wall type without any cladding. We had assumed that the straw would be able to protect itself with the instantly arising charred surface. This could still be true, but we didn't consider that there is an overpressure in the burning chamber of 20 Pa when testing according to this standard. The uncladded specimen probably failed because of the very hot chamber gazes pressed into the burnable straw with 20Pa, and also because oxygen had been easily able to penetrate into it because of the absence of any cladding. The reason we did this first uncladded test was not to build uncladded, we did it because of a buerocratic and safety thing: After a successful test it is always only allowed to build exactly as tested if you want to have fire resistance acknowledged by authorities. Every detail, every material (cladding product...) has to be exactly the same, and we wanted to be free to use different types of plasters etc..

With the successful lime plastered test yesterday we'll be allowed to build acknowledged REI30 walls this one type of lime plaster additional to the use of both sides clay as it has been stated before.
Both walls had been charged with a load of 112 KN on a length of 3m. The requirements for a successful test are mainly: The specimen has to be safe in stability and spatial enclosure during the test burning.

Fire safety requirements in Germany roughly summed up:
<= 2-family house: REI 0 // <=3 storeys and 400sqm: REI 30 // <=5 storeys with unit size <400sqm walls has to reach "K2-60":

3- to 5- storey buildings:
"K2-60" means that the three straw is 60 min protected ("encapsulated") against 200°C and the timber against 270°C during a "full fire". Research in the last two years for the 5-storey office in Verden/ Germany showed that this encapsulation is possible with, lets say, 50-70mm lime plaster and 70-80mm clay plaster (conventionally done by 2x18mm gypsum fire protection boards or 2x18mm gypsum fibre boards). The common 30mm lime or clay plasters might have a protection against this development of off-ing burnable gazes (straw/ timer staring to get brown coloured) for approx. 15-30min. Besides that, before a wall is failing during fire resistance tests there also could happen incomplete combustion with the danger of carbon monoxide poisoning and of course the danger of smoke. These are no standard criteria but should be of interest for us.

Besides joyful-to-read-fire-resistance-results:
Every straw builder and designer should keep in mind that straw insulated components (and of course the timber) are burning and off-gazing during a fire.That means even though we might have successful REI of 30min and more, habitants and fire fighters could be exposed to serious health hazards already actually during earlier minutes of a fire depending of the type of cladding and proper building details. During the testing yesterday we've been accidentally exposed to very high concentrations of carbon monoxide beneath the test specimen, enough for a decent headache, this wasn't that nice. Fire resistance, at least as it is implemented in Europe, in general means only stability and spacial enclosure over a specified time during a full fire. Successful tests don't say anything about health hazards during fire coming from the building components no matter what they are made of. I know, we as enthusiasts don't like these kind of intermediate shadows in the bright shining of straw building but if we want to be better than the others we have to deal with intermediate tones.

If there is interest:
If FASBA will receive donations of about 500€ in total with subject "Translation Fire test 2014" the test report could be published in english done by an acknowledged translator.
Bank: GLS- Gemeinschaftsbank Bochum, Owner: FASBA e.V., Account: 800 7971 500, IBAN: DE 82 4306 0967 8007 9715 00, BIC: GENODEM1GLS
or sending via paypal to info at fasba.de.

Have a healthy, successful year 2014!

Dirk Scharmer - Architect


Fachverband Strohballenbau Deutschland e.V.
FASBA e.V.
Artilleriestr.6
D- 27283 Verden
Email: info at fasba.de
www.fasba.de

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Derek Roff
derek at unm.edu<mailto:derek at unm.edu>


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