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Insulating a Cathedral Ceiling

  • Transcript

    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 …

    KEVIN: Yes.

    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?

    LESLIE: Mm-hmm.

    TOM: Yeah, then you have a second layer of sheathing and then on top of that you have your roofing material.

    KEVIN: Oh.

    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)

    TOM: Alright.

    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.

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