SB: RE: (Loopy's) Rainscreen Claddings

["Dale Banks" <loopy@homernet.net>]

Rainscreen Rob,
Thanks for your insights.  I think your question "Why bother with the bales
in that design ?" should be asked of every house being designed with
strawbales, and is 'kwite kewl' to ask here on this list.  My particular
answer is rather lengthy, but I'd like to address it to help understand the
circumstance.
Background:  The 2x6 studs are locally milled beetle-killed spruce given to
me in exchange for helping someone (so I had these already); I built a paper
bale workshop and plastered it with local clay/sand/straw this summer and
enjoyed working with the earthen plaster as did my family and friends; the
clay is available locally for "dirt cheap"; I enjoy the plastered bale look
and feel;  we needed an addition to accommodate sprouting children; the main
house is sided and we figured the addition should match.
Why bales?  Well, by using the local bales (wild grasses, or "cow hay") and
clay, we will replace the non local fiberglass, sheetrock, housewrap, and
OSB or plywood sheathing typical in "local" construction.  We will also
spend less money on the addition, although the plastering will take longer
than hanging sheetrock.  Loadbearing walls are not an option with these
bales or the local unpredictable weather, so we decided to build the frame
with the 2x6's we have and use bales to provide insulation, a surface to
plaster to, and shear reinforcement (when compressed and plastered) - not to
mention the great window seat options.  We figure we will have a beautiful
plastered interior with a durable, weatherproof exterior that matches the
main house, and we'll use locally available materials.

"Generally-speaking, in order for an air barrier to be effective at its
intended purpose, it needs to be continuous."

This is a good point,and I have considered doing what you describe with
housewrap on the backside of each stud, extending a few inches into each
adjacent bay.  I think your math (below) is wrong, and one could actually
expect 1/16" x [(stud height x 2)+(bay width x 2)] or in my case 1/16*[14+4]
or 1 1/8 square inches per bay- still too much.  I was thinking of letting
the plaster dry and then filling the cracks with more mud or caulk along
each stud instead of using the housewrap.  Any thoughts on that?


Dale

-----Original Message-----
From: Rob Tom [mailto:ArchiLogic@yahoo.ca]

Failing that, I don't think that it'd be unreasonable to suggest that
[(a total crack width of 1/16" per stud bay) X  (stud height+bay
width) = ] ~6 sq inches leakage area per stud bay would develop
once the plaster dries out.
        ~~~ * ~~~
         Rob Tom



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