[Strawbale] Strawbale construction

[Stewart at TSHargrave....uk]

On 8 May 2006 at 15:56, Eric Larmett wrote:

> I am proposing a timber deck on a pile and cradle substructure, timber
> base and floor joists, straw bale wall, vertical battens on the inside,
> horizontal battens on the outside tied through the bales with baler
> string. Between the horizontal battens and the straw will be a breather
> membrane stapled to the base plate and wall plate to seal against vermin
> infestation. External wall finish will be wall tiles vertically hung.
> 
> On top of the wall is a timber wall plate to carry a roofing system that
> overhangs the wall giving a sheltered veranda or walkway.
> 
> The inside face of the wall is finished in a lime plaster.
[..]
> I welcome comments/discussion.


Based on fairly limited experience, two things immediately occur:

1). The render of a loadbearing wall contributes significantly to its stability and 
load carrying capacity. It's a case of the whole being greater than the sum of the 
parts. If render is only applied to one surface of the wall, then roof loads may not 
be evenly supported across the thickness of the wall. Further more, straw may 
continue to settle slightly on the side not supported by the render. This could 
ultimately result in bowing walls, or compromised stability.

2). It is important not to form a fire chimney by leaving an air gap between the 
straw and its cladding.

-- 
Stewart H.