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Re: [Strawbale] Green roofs on strawbale buildings



RT,
I like your illustrative style of explanation.
As an engineer I wouldn't consider load bearing strawbales because the thought of the loads being gradually transferred to the render skin goes against all my instincts. Anyone who has ever renovated an old house will have seen how crumbly lime plaster goes over time. If I am going to devote the time, effort and money to building a home I want it to last for a few hundred years. Besides all buildings need doors and windows and they have frames so it's little extra trouble to use them as part of the structure. I have to admit I have gone a lot further down that path than most, in my strawbalehouse, but it is for a purpose.
Brian
www.strawbalehouse.co.uk


----- Original Message ----- From: "RT" <ArchiLogic@yahoo...>
To: "Euro SB" <strawbale@amper....muni.cz>
Sent: Friday, September 17, 2010 4:38 PM
Subject: Re: [Strawbale] Green roofs on strawbale buildings


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

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.


Dave;

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
confirm:

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 >
manually winnow the chaff from my edress if you hit "reply"
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