[Strawbale] results of sb houses across europe pls

[Derek Roff]

I agree with Dave, that plaster on bales is very important for the 
reasons mentioned.  I would add another major reason, and a couple of 
lesser reasons:

-3- a well-bonded plaster-bale-plaster sandwich functions as a 
stressed-skin composite panel, significantly improving all of the 
wall's structural properties, especially shear, in-plane, and 
out-of-plane load bearing capacities.

-4- plaster skins offer significantly more protection from mice, 
insects, and other critters, which can otherwise be smelly, 
destructive, and/or annoying.

-5- sound insulation is dramatically increased.

Derek

--On Sunday, July 11, 2010 10:13 PM +0100 Dave Howorth 
<dave at howorth....uk> wrote:

On Sat, 2010-07-10 at 22:35 +0000, Neale Brickwood wrote:

> I'm thinking of a dry build using a timber frame to provide the
> structure and dry enclosure with the straw being inserted from the
> inside (in the dry) timber cladding outside, plasterboard inside. I
> know it dosnt stack up with the purist principles but will provide
> substantial Co2 savings by omitting brick, block and insulation and
> obviously sand and cement.
>
>
> I presume i'd need a breathable vapour barrier between the timber
> structure and the cladding which would allow the straw to breathe. 
Do
> you know if any one has done any U value calcs for this type of 
build
> or do you forsee any problems?

Neale,

The term "breathable vapour barrier" is an oxymoron. Breathable means
"vapour permeable". You probably mean a watertight, airtight barrier.

Straw bales are traditionally coated with lime or clay plaster for two
main reasons:
-1- it provides fire resistance
-2- it provides an airtight barrier that helps the straw function
effectively as insulation

Gaps between between bales and separate fireproof layers are known to
act as chimneys in fires and these can increase the spread of flame.

Having said all that, you might want to look at the S-House design.

Cheers, Dave