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RE: GSBN:fire test -- your opinions?



HI all, 

Has anyone thought about testing Clay-lime Plaster?  I have found that
adding a small amount of lime into a clay plaster makes it much more
resistant to water, and fire as well I imagine.

If I were to test lime I would do it without cement, supposing that if
anything the cement would make it more fire-proof and lime (and clay) is
plenty good enough with no cement.  Why is it that Americans are so in love
with cement (being an expat myself and Polish I feel free to make jokes
about both!)?

As for sticking to the walls, I should think that spraying limewash onto the
bales with pressure (so it penetrates) before plastering should allow the
plaster to stick just fine.  As for fire resistance, there is a Spanish
engineer who actually dips the bales in recently slaked lime before
building, and he has taken a blow torch to the bales and says they refuse to
burn...What would dipping just the inside/outside faces of the bales in a
lime-wash do?  Would that make the plaster stick more? Be more resistant to
fire?  Sort of like Tom Rijven«s "French dip" but with lime instead of clay.

And sorry to drone on, but another builder I know mentioned that the fires
tend to start in the roof and work their way into the bales through the roof
beams/roof plate...so shouldn«t we test how long it takes the fire to work
into the bales from above, not the sides?  I don«t know how this could be
tested as I am no engineer.  Just thoughts...        

Rikki Nitzkin
Aul?s, Lleida, Espa?a
rikkinitzkin@...
(0034)657 33 51 62 
www.casasdepaja.com (Red de Construcci?n con Balas de Paja)
 

> -----Mensaje original-----
> De: GSBN [<a  target="_blank" href="mailto:GSBN@...";>mailto:GSBN@...] En nombre de
> billc_lists@...
> Enviado el: mi?rcoles, 26 de abril de 2006 9:57
> Para: GSBN
> Asunto: Re: GSBN:fire test -- your opinions?
> 
> Hi all,
> 
> Interesting points re: edge vs flat, cement vs cement-lime vs lime vs
> earthen plasters.
> 
> I think it's clear that order to really get the full data, more than
> two tests will need to be done. Typically in a scientific procedure
> you'd change just one variable at a time, for instance bales on edge
> vs bales flat, with all other variables (plaster, etc) remaining the
> same. Then you'd vary another constraint, such as the plaster types,
> so that if you'd already done edge vs flat with one type of render
> you'd be able to predict how the performance would vary (or not)
> using different plasters as a result of bale orientation.  Otherwise
> you have trouble saying exactly what caused any difference you may
> have observed.
> 
> I personally don't think that we'll see a huge difference between
> edge vs flat, though I can certainly see the reasoning behind doing
> such tests to be sure.  I don't think molten strings are going to
> make much difference, especially in a test wall which is built within
> a four sided frame - it's not likely that the straw is going to go
> anywhere. The question is more a matter of how heat is transferred
> through the bale - do the hollow straws allow it to move faster
> through flat bales?  Do vertical straws cause heat to move to the top
> more quickly, causing failure there?
> 
> 
> Regarding plasters, curiosity got the best of me and I pulled some
> numbers from the SB Registry to see just what people are using on
> their walls.  For exterior walls, they can choose from:
> 
> cement plaster
> earth or clay plaster
> lime plaster
> wood siding over plastered bales
> wood siding over unplastered bales
> other - Describe if other
> 
> or any combination of the above.  Of those who reported their
> exterior finish, the resulting numbers are:
> 
> Exteriors:
> 
> Cement only: 235
> 
> Earth only: 72
> 
> Earth/lime: 34
> 
> Lime only: 51
> 
> with a scattering of other strange combinations (perhaps different
> treatments for different walls).  For interior walls, they can choose
> from:
> 
> cement plaster
> earth or clay plaster
> lime plaster
> gypsum plaster
> wood
> sheetrock
> other - Describe if other
> 
> or any combination.  The resulting numbers are:
> 
> 
> Interiors:
> 
> Cement only: 116
> 
> Cement plus other: 39 (includes cement &amp; gypsum, cement &amp; sheetrock,
> cement &amp; wood, etc)
> 
> Earth only: 94
> 
> Earth &amp; Gypsum: 13
> 
> Earth &amp; lime: 13
> 
> earth &amp; other: 15
> 
> and again, a few who did other, more bizarre combinations.
> 
> 
> So though these numbers are by no means definitive, it looks to me
> that cement beats earth for exteriors in general by about 2 to 1, but
> they're pretty close to an even match for interiors.
> 
> Which then begs the question:  Are we testing for fire resistance of
> interior walls or exterior, or both?
> 
> On the flat vs edge orientation, I see 316 flat vs 84 on edge.
> 
> I don't know if those numbers will help anyone make a decision, but I
> figured I'd throw them out there.  There's more reported use of earth
> plaster than I expected there to be.
> 
> 
> --
> Bill Christensen
> <<a  target="_blank" href="http://sustainablesources.com/contact/";>http://sustainablesources.com/contact/</a>>
> 
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GSBN is an invitation-only forum of key individuals and representatives of regional straw construction organizations. The costs of operating this list are underwritten by The Last Straw Journal in exchange for use of the GSBN as an advisory board and technical editing arm.

For instructions on joining, leaving, or otherwise using the GSBN list, send email to GSBN@...HELP in the SUBJECT line.
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