[Strawbale] Green roofs on strawbale buildings

RT ArchiLogic at yahoo...
Fri Sep 17 17:38:28 CEST 2010

On Thu, 16 Sep 2010 16:37:52 -0400, Dave Howorth <dave at howorth....uk>  

> On Thu, 2010-09-16 at 15:02 -0400, RT wrote:
>> Perhaps it would be useful to mention that with load-bearing SB walls,  
>> it will ultimately be the plaster skins that take the gravity loads.
>> As such, it's a matter of detailing the plaster properly to anticipate  
>> the intended design loading.
> Would you mind providing a reference for that? I have no trouble
> believing that the stiff plaster takes dynamic loads, but I don't see
> why it would take the static loads, given precompressed bales and all
> static loads applied before the plaster is applied. So experimental
> evidence would be very valuable.


Just curious as to how you think a SB wall assembly differentiates between  
the dead and live components of the gravity loads to which it must respond  
and then proceeds to direct the straw portion of the wall to deal with  
only the dead load component of the applied loads ?.

(And I don't think it's reasonable to assume that all of the dead loads  
will be in place at the time of plastering. ie think of multiple storey  
structures as a "for instance")

To anyone who has any doubts about the harder/stiffer elements taking the  
loads I would suggest a simple demonstration they can do on their own to  

Find a piece of deep pile broadloom or carpet and place a few small stones  
into the carpet in a manner that the carpet strands stand proud of the  
small stones.

Then place a chair or ladder next to the piece of carpet, take off your  
shoes and socks and climb up and then jump onto the stone-studded carpet.

When you recover, comment as to which element (hard stone (analagous to  
the plaster in a SB wall assembly) or the compressible carpet (analagous  
to the straw) took the load .

As to official in-lab test data, any of the compression resistance tests  
done on plastered wall panels (in North America, Europe, AUS or NZ) will  
provide the same "evidence".

Those same tests will also show the importance of proper detailing of the  
plaster to deal with the expected failure modes (ie Euler buckling,  
localised crushing, delamination etc.)

=== * ===
Rob Tom
Kanata, Ontario, Canada
< A r c h i L o g i c  at  Y a h o o  dot  c a >
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