Concrete thermal blanket for basement vapor barrier

15 years ago

Hi all, I am going to put up a vapor barrier on my poured concrete crawlspace walls. I was going to use 6 mil poly, but a buddy gave me a Grip-Tite concrete curing blanket. This product has a vapor barrier, radient layer, and an R value of about 2.5. I would need to cut it into 5 foot strips to install.

This sounds like it might be a good alternate use for this product. Does anyone have any direct experience with these blankets that can shed light as to why I should not use it for this application? It seems like such a good fit, I cannot understand why it has not been mentioned (or done) before.

Thanks

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Comments (8)

jamesbodell
Original Author
15 years ago
There is NO radiant layer, not sure where I got that from, and I would not have to cut it as its at 6ft already. I thought it was a 16x16, but its 6x25.
sierraeast
15 years ago
As long as it is a vapor barrier, you might as well use it. Im going with heavy poly. The most important thing is to insulate any pony walls and run the membrane to the sill plate and seal it by caulking and stapling to the sill. You'll want to make sure your rim board areas are insulated as well , typically with spray foam or cutting foam panels inbetween joist spacing allowing perimeter gaps so you can fill them with caulk or out of the can spray foams when adhering.
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jamesbodell
Original Author
15 years ago
I had considered using foam boards and expanding foam to seal in place around the box but have a dilema. You cannot easily remove the foam for termite inspection. While I have no current termite activity, I have had some in the past and had to hire an exterminator. I actually pay a maintence fee for a yearly inspection.

I have caulked the gap between the floor (well, ceiling in the basement) and box where some air was coming through, and I was thinking of using glass insulation in the box.
BUT:
I DO have mice in winter. They love to live and breed in the glass insulation.

Thus the dilema!
mightyanvil
15 years ago
What is the purpose of the vapor barrier?
jamesbodell
Original Author
15 years ago
Trick question? To keep water vapor out of my house. I already have it on the floor.
mightyanvil
15 years ago
What is the source of the water vapor at the walls?
GammyT
15 years ago
As Mightyanvil asked, what is the source of the water?

Also, how old is the house? Brand new and old are two different things.
jamesbodell
Original Author
15 years ago
Sorry. The addition is 16x16 and 4 years old. Its poured concrete, and is under the kitchen, so lots of water lines.
The rest of the house varies from 30 to 100 years old.

I have 6mil poly on the floor, which is very uneven as its ledge. Only 2-3 feet of working room, and hard on the knees.

I want to put the barrier on the walls and lap it it over the poly on the floor to make a better seal. The insulation is a benefit as it will help keep the space a little warmer. Currently, I have fiberglass insulation pushed up in the joists, but I am considering taking that down. Also, some of the wall space has 2" XPS foam boards attached with contact cement.

I also still have condensation down there, and some mold, but I plan to get a dehumidifier next summer.

The only remaining question is foam or glass bats in around the box of the house.