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Re: GSBN:plaster and straw question



At a wood/plaster interface, the water is trapped, and remains in place
as the temperature rises, so the critters start a-molding.  I saw
abundant evidence of just this behind every failed stucco wall (about
30 of them) that I inspected after the 1989 San Francisco earthquake.
Even where there were two layers of grade D paper as per code, water
had gotten behind it (the paper) and there was, typically, lots of rot
in buildings over ten years old.

Hmmm.

So what then would be your recommended detail for something like this
(excuse the ASCII art):



		Exterior

plaster
----------------------------------------------------


                Bale wall

-----------------------------------------------------
	|        |         plaster
        |6x6 post|
        |        |
	----------


              Interior


At some point on one of the many lists, the general recommendation
was to put plywood or OSB on the bale side of the post, extending out
to the left and right some distance (6" or more comes to mind).
Expanded metal lath goes over the ply and extends over the bales.  A
bead of caulk was recommended at the interface between post and
plaster.

In theory this kind of setup would avoid cracking and air
infiltration at the wood-to-plaster interface. But if the wood's
going to rot back there, it might not be a great idea after all.

I believe this was intended for cement plasters.  We're going to be
doing earthen plaster... so that probably changes some things.  One
other difference is that we'll be building in Texas, and the heat and
humidity is outside and cool and dry (hopefully) will be inside.




--
Bill Christensen
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