Insulation: How to Keep Heat Inside
LESLIE: Sebastian in New York, you’ve got The Money Pit. How can we help you today?
SEBASTIAN: Yes. I have a 1940s brick-sided bungalow, or Cape Cod, in Michigan. It has plaster walls ventilating on the interior.
SEBASTIAN: I was told the best – and it has no insulation in the walls. I was told the best way to insulate this is by going from the outside, drilling through the mortar joints and pushing the cellulose. I just didn’t feel confident this was the proper way of doing this.
TOM: Yeah. No, I don’t think so. Typically, you don’t insulate that type of an exterior wall. I mean there’s just really no effective way to get insulation in there; there’s no wall cavity for you to fill out.
LESLIE: Mm-hmm. And the stones should be insulating enough itself but it generally isn’t.
TOM: (overlapping voices) Yeah. Believe it or not, the air that’s trapped inside of it. So what I would focus on in your house, Sebastian, is two things. In terms of the exterior walls, I would concentrate on air infiltration; so that means good-quality windows, proper sealing, weatherstripping and caulking.
But most importantly, from an insulation perspective, it’s everything that’s above you because 80 percent of your heat loss is going to go up; only about 15 percent goes through the exterior walls and about 5 percent through the floors. So I would concentrate on making sure that you have at least 19 to 22 inches of insulation in the attic space, because that’s going to do the best – that’s going to be the most effective way at cutting down on utility costs and improving comfort.
SEBASTIAN: OK. The walls actually feel like an ice cube; when you’re laying there in bed, you can actually feel the cold coming off the walls. It’s really extracting; the temperature flows from hot to cold and you can really feel it leaving your body.
TOM: What kind of insulation do you have in the attic space?
SEBASTIAN: That I know I can put in, because I just put in – I just added 2x6s up there; it’s on top of the original [inaudible at 0:04:19.7].
TOM: (overlapping voices) Yeah. I think what you’re going to find is this: when you insulate the attic, you’re going to find that you have, all of a sudden, more heat in the house and that’s going to make those walls warmer.
TOM: Because you’re losing a lot of heat.
SEBASTIAN: OK. Very good. Thank you.
TOM: Give it a try, Sebastian. Thanks so much for calling us at 1-888-MONEY-PIT.