Insulation Tips for a Slab House
LESLIE: Dean in Utah has a question about insulating a slab house. Dean, how can we help?
DEAN: I want to save energy by insulating my slab floor in my existing house.
DEAN: And I understand that some of this foamboard can be used but that there’s an optimum angle at which to place that foamboard next to your house. It doesn’t need to – it’s not good to have it parallel to the foundation wall but at some angle going out into the soil.
TOM: Now, your goal here is to warm the first floor of the house or is there a basement? What area were you looking …
DEAN: No, it’s a slab, one-story house.
TOM: Alright. Well, what you’re talking about is putting insulation against the outside of the foundation walls, correct?
DEAN: Right. Exactly.
TOM: OK. And this is a house that’s already constructed, right?
TOM: This is not one you’re building. So, in order to do that you’d have to excavate out the soil around the house.
TOM: That’s a boatload of work for a little bit of benefit, my friend. I’m not so sure I would do that. Just a lot of work and if you’re looking for ways to make your house more energy efficient and make your house warmer, there’s probably a lot of other things that you can do besides that. You’ll pick up a little bit of insulation by doing that but man, that’s a lot of work; excavating all that soil, getting it out so you can get down a couple of feet and putting foamboard against the walls. A lot of work for a little bit of benefit.
I would rather suggest that you look into having an energy audit done and I would be surprised if you didn’t find a dozen other places where that energy and that money is better spent to reduce the cost of operating your home, sir.
LESLIE: And Dean, your energy provider can do that energy audit for you. Many – you know, a lot of times these companies will do it for little or no charge and then they basically tell you where these energy leaks are around your home and give you some ideas on how to fix them.
TOM: For example, you may very well have gaps between the bottom of the sill, which is the bottom framed piece of the wall, and that slab that could be letting air in that needs to be sealed up. And …
DEAN: It’s a concrete block house, so …
DEAN: … there’s no gaps there.
TOM: Well, you know, there’s a material called Sill Sealer that’s supposed to be in between the frame of the wall and the top of the concrete block. And there could be. The thing is, you can’t see them but there’s tools that actually help energy auditors find those drafts and find those gaps that could seal them up. Just one example. But I think I would recommend against excavating the house and putting the foam on the outside. I think it’s too much work for not enough benefit.
Dean, thanks so much for calling us at 888-MONEY-PIT.