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mcvane 02-01-2010 10:59 AM

properly insulating a crawlspace
Hi All.

I am planning on insulating my crawl-space, and from reading previous posts, it is a crawlspace (basement area) where it's relatively dry, an extension of my basement and I can store things there. The size is 4' high and the length of the crawlspace is about 20' x 15'

It has never been insulated though and it has bare concrete walls. So, I live in Toronto, Canada, and we paid money for a energy inspection and the report stated that the crawlspace insulated will help in warming up the room above it which is the family room.

This is my plan (as suggested by home depot - yeah..not sure if that's the right advice)

Frame the wall with 2x4s, 16" appart, drill the bases to the ground...and insulate with the batts of R12 insulation. Then, after the insulation is done, cover everything up with Vapour barrier...

So, in essence, right against the concrete wall the studs, then the insulation and cover the inside part of the basement with the vapour barrier.

Is this the right way to go? I got a bit of a lecture from the home depot guy that said that I should put a vapour barrier right against the concrete, but I knew that wasn't quite right...I always thought the vapour barrier goes on the extreme inside of the living keep the moisture out...

Anyways, any opinions/advice would be appreciated...


Scuba_Dave 02-01-2010 11:35 AM

Normal wood is not supposed to be up against concrete/block
Best bet is rigid foam up against the block
You could go with thinner R3, then build your wall

Or some people just use 2" thick R10 rigid without a wall
Depends upon the area, what you need, if critters can get in there to chew on the insulation
My last house had 1" insulation installed aroudnthe perimter
But the floor of the house was also insulated

Is the floor dirt...concrete ?

mcvane 02-01-2010 12:18 PM

...The floor is totally gaps or crevices in the corner or anywhere. Built pretty well it appears.

Maybe I should put that black tarp type material against the floor/wall where I drill in the holes for the wood?

Or maybe i need 2 sets of vapour barrier: One against the concrete, put the 2x4 studs and insulation in between and then have another layer of vapour barrier on the inside?

Maybe it's overkill?

Scuba_Dave 02-01-2010 12:54 PM

Is there a vapor barrier on the outside of the block - the tar like stuff ?

mcvane 02-01-2010 01:08 PM

I assume there is a vapour barrier on the exterior wall.

The reason I can say this is that in the crawlspace which is 4 feet in height, there is a part where wood beams have been installed by the builders and I see an overlap of the tar type black sheets on top of the concrete where the wood was screwed/nailed into place.

I think this house was well built, but we moved in about 2 years ago.

I hope that makes sense?

Gary in WA 02-01-2010 08:56 PM

"Or some people just use 2" thick R10 rigid without a wall
Depends upon the area, what you need, if critters can get in there to chew on the insulation" ------------- You need to cover foam board in your case:

Be safe, Gary

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