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

[Dirk Scharmer]

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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