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johnwest's picture

Double VB? (post #215902)

Hello,

 

I live in Toronto, Canada. I have a bonus room over a garage that gets pretty hot in the summer and cool in the winter (no hvac in thsi room either). It has R12 batts with an interior vapor barrier. The inside of the knee wall is unface, so my plan was to cover up the exposed batt side in the attic. I purchased Silverboard but I thought I was getting Silverboard XS. After installing everything, I realized I received the wrong product. If I don't tape the seams, can I avoid creating a double vapor barrier? I didn't really do a perfect air sealing job since it is a best effort retrofit. I'm wondering if I should scrap it all and just use something like a building wrap. It is only 1/2" Silverboard.

 

Thanks

If the VB is on one side of (post #215902, reply #1 of 3)

If the VB is on one side of the board then you could score/scratch the board to break down the vapor barrier a bit.  You don't need to destroy it, just make it leakier than the other barrier.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

It goes, drywall, (post #215902, reply #2 of 3)

It goes, drywall, polyethelyne, batt insulation, Sliverboard. So the insulation is basically sandwiched in there between the two vapor barriers. The board I added is definiltey leakier, but only at the seams. They're 2x8' sheets - i had to break them down to fit them into the attic space.

Yeah, use something to (post #215902, reply #3 of 3)

Yeah, use something to scratch the silver.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville