Insulating a Cathedral Ceiling
LESLIE: Kevin in Texas is calling in with an insulation question. What can we do for you today?
KEVIN: Hi. I’ve got an older house that a guy built and he put 2x4s for the ceiling joists and when I look up in the house, the ceiling is underneath and I’ve got 10 on top and there’s not enough room for really insulation too much in there. And these 100-degree Texas days are really killing us and I was just curious what I could do to try to get some more insulation in there.
TOM: See, in a house like that, where you’ve got a cathedral roof and you’ve got exposed beams …
TOM: … the best way to insulate that is from the outside, believe it or not. You use sort of a sandwich roof.
LESLIE: (overlapping voices) Like foam sheathing.
TOM: Yeah, use like a foam sheathing; very thick, like about four inches of foam. Then you have a second layer of sheathing.
KEVIN: And put that – like take the tin roof off and put that down?
TOM: Yeah, then you have a second layer of sheathing and then on top of that you have your roofing material.
TOM: So that’s how that type of a house has an insulated roof or an insulated ceiling. So it’s insulated from the outside, not from the inside, so to speak.
LESLIE: And then is there any sort of coating that would be beneficial to the roof surface on the exterior at all?
TOM: Yeah. There’s a low-e coating you can put on that. It’s basically a high-tech paint that helps reflect some of the heat out.
KEVIN: OK. Yeah, I have that on there already but still.
TOM: Yeah, that’s a good last step.
KEVIN: Yeah. OK. What about the spray-in foam insulation? That wouldn’t be a …?
LESLIE: (overlapping voices) Well, you’re probably maxed out in there.
TOM: (overlapping voices) You just don’t have enough inches of space there to get much r value.
KEVIN: OK. That’s one of my big concerns; my question was about the spray-in.
TOM: (overlapping voices) Yeah, that’s the issue. OK?
KEVIN: I didn’t know what the r factor was on four inches. (chuckles)
LESLIE: Probably not much.
KEVIN: Not much. OK, well that kind of gives me idea what I need to do then.
TOM: Alright. Good luck with that project. Thanks so much for calling us at 888-MONEY-PIT.