Alternative outside wall finish

["Pierre Masson" <pmasson@isn.net>]

Hello all,

I've been thinking for some time about alternatives to the stucco rendering on 
exterior walls (whether lime, portland, earth and clay, etc).  Here are my 
latest ideas on a way to do this.  This would be for non-load-bearing infill 
strawbale walls.  Please see the attached jpg file, for details.  The problem I 
had was in incorporating a thin stucco layer between the shingles, for 
instance, and the bales, so as not to create an air channel for flames, 
critters, etc.  My solution is to use ladders made of 2x6 and 2x4, or whatever 
dimensions would be required by the size, load requirements, etc, and to 
insert the bales in between.  Nothing new here, this has been done by 
others.  I think there's a picture in "The Straw Bale House".  The trick for me 
will be to do all the exterior sheeting (diagonal 1x T&G boards, OSB, 
plywood, whatever) and the shingling or clapboard or other exterior finish first, 
then install the bales.  I would butter the exterior side of the bale with stucco 
(say 1/2"), then shove it in between the ladders, so that it would make good 
contact with the inside face of the sheeting.  On my drawing (plan view), I 
have inserted a sheet of newspaper that would separate the stucco from the 
sheeting to make it easier to make eventual repairs on the outside finish, but 
I'm not quite sure that it would make much of a difference anyway.  The 
inside could be finished with a standard earth, lime or stucco rendering.

Another advantage is that when the bales are finally installed, there is no 
danger of them getting wet... not trivial.  I would also the roof already done at 
this stage, so it would be fairly easy to store the bales in the shell of the 
house.  I'm planning to use this technique this summer on a small building, 
and see how everything works out in actual practice.

Disadvantage would perhaps be the amount of wood required, but this would 
worth some number crunching (and the wood could probably be mostly 2x4 
and 2x6, which are fairly small cross-sections, specially if one were to use 
rough lumber which is really 2 x 4, not 1.5 x 3.5 (8 square inches versus 
5.25)).

Comments and other ideas are quite welcome. 

Bye for now, Pierre

Pierre Masson
Prince Edward Island, Canada
pmasson@isn.net

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