Use Vapor Barrier to Warm Up Drafty Floors
LESLIE: Rob in Washington has a call for The Money Pit. How can we help you?
ROB: I just built a new house and we’ve moved in – there for about a year or so. And we’ve noticed that the floors – it’s kind of drafty on the floors and they’re really cold. And I was wondering if you have any recommendations for adding some type of insulation barrier for under the house in addition to the insulation we have down there right now, which I don’t think is doing the job.
TOM: You have insulation in the floor joists now under the house?
TOM: And do you know how thick the insulation is?
ROB: I’d say it’s probably eight inches.
TOM: Well, that’s pretty good. The other thing that you could do – is this over a dirt or a concrete floor?
ROB: This is dirt.
TOM: Well, what you want to do is you want to make sure you cover the soil with a vapor barrier. Cover it with plastic sheeting; as few seams as possible. And the reason for that is because you’re going to get a lot of moisture that’s going to evaporate off the soil floor and get into the insulation. And when you take insulation and you make it damp, it loses its ability to insulate. In fact, if you add just two percent moisture to eight inches of insulation, it’s going to lose about a third of its r factor. So that’s why it’s important for that to be dry. So I would suggest that you try to dry the area out, add a vapor barrier, make sure you have ventilation on the sides of the foundation. And that will help and get that insulation as dry as it possibly can be.
ROB: Great. Well, I’ll go try it, make it happen.
TOM: Give it a shot, Rob. Thanks so much for calling us at 888-MONEY-PIT.