[Strawbale] Re: Strawbale Digest, Vol 9, Issue 1

[Rene Dalmeijer]

Eric,

The tests done by John Zang in Australia show that about 4% compression 
of total wall height is required. This will not solve the differential 
settlement of SB walls and the window frames. SB walls with earth 
plaster will always display a certain percentage of creep over time, 
much more so then vertical wood posts. At present we have very little 
idea how much creep besides that it is not much. Reports vary from 50mm 
to less then discernible. Where a few mm is the most common. I suppose 
50mm takes place where insufficient pre-compression has been applied.

Besides the above I would seriously recommend you to reconsider the use 
of threaded bar to pre-compress the straw bales and use packing straps 
instead. The threaded bar is a real pain in the neck and it also 
creates a condensation point right in the middle of the bales. In most 
cases where SB walls have been taken down revealing the central pins 
show decomposing straw around the all thread specifically in the bottom 
bales. The condensate trickles down the all thread.

Rene
On Jun 3, 2006, at 12:03, strawbale-request at amper....muni.cz wrote:

> Hi guys
>
> Interesting thoughts.
>
> We are considering a straw bale wall for approx 50% of the external 
> wall
> with the other 50% made up of glass.
> We have identified the issue of differential settlement and considered
> pre compressing the straw bale walls.
> Essentially we would have threaded bar inside the bales (2 per bale).
> These would be fixed to the sole plate and the wall plate would be
> tightened down to compress the bales. Thus taking out the initial
> compression.
> Do you know of any figures (rule of thumb) to apply to the compressive
> nature of the bales.
> The roof would be supported by both glass and straw bale walls.
>
> Cheers
>
> Eric Larmett
> Senior Engineer