[Greenbuilding] [BULK] Re: Mold questions

[Lawrence Lile]

>Lawrence Lile has mentioned that he caulks the stud/ sheeting
connections and the horizontal spaces between the sheeting to prevent
moisture infiltration.
Another way to do this, add some insulation, and cut down on all that
caulking would be to install inuslboard with the aluminum foil coating
on it. The foam panels can cover the joints between the sheeting if
offset by, say, 12".  Being foam, the moisture won't pass through the
panels. The joints between the foam panels can be taped over with Tuck
Tape or some such.

I decided to avoid the foil faced insualtion, prefering materials that
allow some moisture transport.  Extruded foam does allow some moisture
to move (not a lot) whereas foil faced does not.  I am convinced that
the ability to dry is more important than low permeability.  

Also, I am worried about placing the foil faced on the outside of a
house, the wrong side for a vapor barrier in my area.  In addition, I
have understood that the foil faced insulations, which start out at a
really high R value, end up outgassing the blowing agent and then losing
R value over the years.  All foams have this problem, but the
polyisosyanurate has the problem to a greater degree.  This comes from a
contractor, I don't have a reference for any reasearch on this.  

The manufacturer of Extruded foam board recommends a 1/4" gap between
boards for expansion and moisture movement, with no tape cover.  Tyvek
over the top will keep air from moving through the gaps.  

Your Mileage May Vary, of course. 

--Lawrence Lile