Attic Insulation and Venitlation
LESLIE: Susan in Texas has a question about insulation. How can we help you today?
SUSAN: We are fixing to insulate our ceilings in our house. We had a new roof put on and it’s black and we have thought about that kind that you blow in and it expands.
TOM: Yes. Mm-hmm.
SUSAN: But I didn’t know what the cost would be as opposed to the regular fiberglass that you either blow in or just lay in. And also, what it would do to the shingles on the roof if you had that sun beating down on that black roof and that barrier, where the heat can’t get through to the attic at all.
TOM: Well, I mean, here’s the thing: the insulation belongs between the heated space and the unheated space or the cooled space and the uncooled space, in your case, in the summer. So, spring insulation to the underside of the roof sheathing means that your attic now becomes conditioned and I don’t think that’s what you want to do.
I think that the foam insulations are very good in new construction; I’m not so convinced that they work that well in retrofit. So what I would tell you to use is to use blown-in or batt fiberglass insulation and I would tell you to use 19 to 22 inches. And most importantly, make sure you add additional ventilation to the roof structure because most attics don’t have enough ventilation and you want to make sure that the space can really breathe. That’s going to give you comfort …
SUSAN: OK, like wind turbines?
TOM: (overlapping voices) No, not wind turbines. They look fancy …
LESLIE: Like a continuous ridge vent.
TOM: Yeah, a continuous ridge vent, like Leslie said. Much better.
SUSAN: A continuous ridge vent.
TOM: Yeah, it goes right down the peak of the roof.
TOM: You won’t even see it when it’s installed and it lets lots and lots of hot, moist air out of the attic.
SUSAN: OK. Well, I appreciate that, then.
TOM: You’re very welcome. Thanks so much for calling us at 1-888-MONEY-PIT.