Canned spray and vapour barrier
PJ109
| Posted in Green Products and Materials on
Hoping to get some insight,
We are about to complete attic air sealing on a 2000 home in climate 7A, which has a 6mi poly on the ceiling with cellulose insulation.
The vapor barrier/air barrier isn’t very well sealed around the light, wires, and plumbing stacks.
I am planning on taping all the softshell electrical boxes, and spray foaming where the wires/plumbing vent pass throught the top plates.
As a preventive measure, I want to spray foam where the vapor barriers meet the top plate along the perimeter of the exterior wall and the interior partition walls as a preventive measure since we are doing it.
I am trying to locate a canned spray foam that will stick to the vapor barrier and wood. I tried several canned foams to no avail.
To anyone’s knowledge is there a brand of canned spray foam that does stick to plastic/vapour barrier?
Much appreciation.
Much appreciation.
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Replies
That 6mil sheet is most likely polyethylene (which is what "poly" is short for). Not much will stick to polyethylene reliably. I have found that canned foam, and closed cell spray foam (I haven't checked open cell for this) do seem to adhere to polyethylene reasonbly well. I have used both the usual Great Stuff and also Loctite's Tite Foam for this kind of thing, and both seem to stick reasonably well to polyethylene. Polyurethane sealants also stick pretty well.
If you want to get it to stick a little better, try roughing the surface of the polyethylene in the area where you're trying to seal it. Use some fine grit sand paper for this (220 or even finer), and lightly sand the poly until it looks frosty instead of clear. All you need is some surface roughness and any adhesive should be able to hold to it better.
Bill