I am putting insulation in a bedroom wall in my home,i was told i also have to install a vapor barrier. I have 3 mil plastic but i don't know if thats enough. My home was built in 1892 and it is balloon frame construction. and there is no insulation in walls. We live in the midwest just outside Chicago,and had much experience with severe winters.
3 mils isn't much. Even if it was enough to be effective, getting it installed without tearing it, making holes, etc I don't think will be easy. A product designed as a real vapor barrier is several times as thick.
Even though it's only 3 mil, it would probably work fine, but I agree with Trader that it'll be harder to work with because it'll be easily damaged.
Whatever you do, DON'T use two layers of 3 mil plastic to make a 6 mil vapour barrier. If water ever gets between those two sheets (from a flood, or whatever) it'll never dry out and it'll be a breeding ground for mold.
The building code here in Canada requires 6 mil polyethylene plastic for vapour barrier.
But, the truth is that when companies make this plastic, it's thickness can vary. So, if you buy plastic that claims it's 6 mil, that means that the thinnest area in the roll is guaranteed to be 6 mil or more.
You'd be better off just buying something labeled as "vapour barrier", in which case it's probably about 6 mil on average. The stuff that's guaranteed to be at least 6 mil at it's thinnest point costs a lot more than something that just claims to be "vapour barrier".
nANCY C posted for all of us...
And I know how to SNIP
I just got a sample of a new vapor barrier material that has some plastic squiggles on it to allow the moisture that inevitability gets behind the siding to drain. I can't remember the name.
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