Should You Ventilate a Spray Foam Attic?

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    LESLIE: Joe in Rhode Island, you’ve got The Money Pit. What’s going on with your spray foam attic?

    JOE: Well, we built a new home.

    TOM: Yep.

    JOE: And it’s 2×6 construction with a truss roof.

    TOM: OK. Yep.

    JOE: And I used opened-cell, spray foam attic and they come in and then they shave it all down to the studs.

    TOM: Yep. Yep.

    JOE: So, we have a completely sealed envelope of the structure itself.

    TOM: OK.

    JOE: Now, when – it’s a truss roof, so there’s really no attic. But there is a space up there.

    TOM: OK.

    JOE: When you sheetrock the whole ceiling and close that off, do I need to be concerned with some sort of ventilation in the spray foam attic space?

    TOM: No, not at all. Not at all.

    Where did they insulate in the attic? Did they insulate under the roof itself or …?

    JOE: They insulated the roof, right to the plywood roof.

    TOM: Yeah. Nope, you absolutely do not need to ventilate a spray-foam house and here’s why: because, basically, now that attic is a conditioned space.

    I have a spray-foamed attic. It’s terrific because it’s pretty much the same temperature as the rest of the house all the time. It used to be that it was, you know, super hot in the summer and really cold in the winter. Now, it’s pretty much even-steven. And the fact that you used spray foam means that it expanded and sealed all the little cracks and gaps and crevices, so you’re not going to have any problems with drafts getting in there.

    JOE: OK.

    TOM: So you do not need to ventilate that roof.

    JOE: Oh. How about – we have mechanical equipment up there. I have the air-conditioning unit up there.

    TOM: Yep. Mm-hmm.

    JOE: No concerns with that, in that space, either?

    TOM: No. It’ll even work better because now, when it’s trying to cool in the summer, it’s not going to be doing so in an attic space that’s 110 degrees.

    JOE: Alright. I was concerned because there’s absolutely no ridge vent, no soffit vent and no …

    TOM: Yeah. No, that is done correctly. And we have to start thinking differently. Now, we use attic ventilation when we use products like fiberglass, because we have to manage the moisture. But with spray foam, ventilation is not an issue. That is now a conditioned part of your house, just like any room in your house.

    JOE: OK.

    TOM: You may not have heating ducts up there but it does not need to be ventilated.

    JOE: Fantastic.

    TOM: Alright? That’s a good choice.

    JOE: Alright. Alright. Very good.

    TOM: Good luck, Joe. Thanks so much for calling us at 888-MONEY-PIT.

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