[GBlist] vapor barrier question

[Thomas Deerfield <tom@ti.cz>]

Y'all,
Here is a curve-ball question for you.
I am about to install blown cellulose in the attic of a home in 
Far-Northern California, on top of the existing 2 layers of 3.5 inch 
fiberglass batts. I am at 3,500 feet elevation, with somewhat hot summers 
and cold winters.

When the original insulation was installed, they put one layer of 3.5 inch 
foil-faced batt with the foil vapor barrier down, as instructions and 
common knowledge agree it should be. Then they put the second layer with 
the foil barrier facing the attic, for unknown reasons, (perhaps they 
thought it would act as a radiant heat shield?).

My question is how to proceed. Advice from local insulation contractors has 
conflicted:
1) tear off the top vapor barrier (dusty, nasty job)
2) slash the top foil with a knife, then blow on top;
3) leave it as-is and blow right over the whole sandwich.

Comments?
Thomas


Thomas Deerfield
The Shasta Group
PO Box 560
Mount Shasta, CA 96067


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