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Re: [Strawbale] Planning a home of BigBales 2011 in Estonia

Hello Dave,

Have you read Buce King's book?
It is easy to proove that plaster plays an important structural role in plastered bale walls: plaster a bale on 2 sides and (once the plaster is dry) push with your hands on the bale. Push with the other hand on a non plastered bale. The difference in stiffness of the bale your hands will expérience results from the resistance added by the (rigid) plaster. Even an important gap between plaster and the roof bearing assembly would not take away this phenomena.
So if we agree that plaster plays an important structural role we can debate wether one wants to use this strengh for live and/or dead loads. If possible, I would like the straw to be able to resist to all the normal loads (dead and live) and have the plaster as a safety margin for when mother nature throws that amazing storm/snowload/earthquake at your building.
After having seen a presentation from a Peter Braun (a Swiss engineer) on the Big bale buildings he designs I have come to no longer think of loadbearing big bale building as something simple. He often expérienced differences in settlement during the build and he came up with different ways of counterbalancing them. True, he seems to me to like the challange of making complicated buildings... 
Me, I prefer simple buildings.
I also think it is great that not all people are like me...

All the best,
Andre
France


Le 26/02/2011 21:32, Dave Howorth a écrit :

On Sat, 2011-02-26 at 12:16 +0100, Caroline Meyer White wrote:


A load bearing strawbale wall is carried by the plaster skins. It can
be hard to understand, as they are so thin. But because the plaster is
always more stiff then the straw, relatively, the load ends up on the
skin, - untill they crack, then it will go to the bales at some point.
The density of the bales etc does have some relevance, but less then
perhaps expected.

I'm sorry but I believe this is a canard. An oft-repeated
misunderstanding. The simplest way to understand is to remember that the
normal way of building is to build the wall, then apply the load, then
apply the plaster. So whilst the plaster may take the bulk of live
loads, the bales frequently take the bulk of the dead load.

There are documented cases of loadbearing walls with noticeable gaps
between the top or bottom of the plaster and the wall plates. Check the
other SB lists for details.

Of course it all depends on specifics. If the plaster is applied and
allowed to dry first and dead loads are applied subsequently, then the
plaster will bear more load. If the bales are precompressed with straps
or studding, they will bear a greater proportion of the load.

Cheers, Dave

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