Facing Insulation in a Crawl Space

Facing Insulation in a Crawl Space

LESLIE: Randy in North Carolina, you’ve got The Money Pit. What can we help you with today?

RANDY: I’ve got some insulation. It was, I think, only 39-and-a-half inches wide and it was about – and the strips put under my house.

TOM: OK.

RANDY: And my nephew put it up but he put the paper – it’s got paper on one side and it’s facing downward into the floor. A friend of mine told me that was backwards; he said that wouldn’t serve the purpose like that.

TOM: Yeah. Well, you’ve got a smart friend there; that is upside down. You essentially put the vapor barrier upside down. The vapor barrier – the rule of thumb, Randy, is that the vapor barrier always go – points towards the living space or the heated space. So that should have been up.

RANDY: OK. Because I’ve got my furnace under the house; you know, the furnace is under the house, too.

TOM: Well – but the crawlspace is not heated so, again …

RANDY: Right, right. Exactly, exactly.

TOM: (chuckling) I understand the heater is in the crawlspace but that’s not the heated space. The heated space is upstairs; hence, the vapor barrier should have been up against the underside of the floor.

Now, I’ve got a trick of the trade for you, though. And that is that you can go down the crawlspace and you can cut that vapor barrier about every six inches; kind of slice it. That will allow some air to breathe through there and help it dry out. The problem is you can trap moisture in there, so you need to slice it so it has some ventilation.