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Community and Q&A

Spray foam insulation under roof sheathing

nuckl00 | Posted in General Questions on

Your article describes that you don’t need any ventilation if you do spray foam insulation under the roof sheathing. But will heat get trapped between the ridge and ridge beam? Because when you have a 3 ply beam for the ridge, it forms a trianglular cavity in between. Do I need to worry about heat or humidity getting trapped in that space? I can’t seem to find any discussion online relating to that…..

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  1. Expert Member
    BILL WICHERS | | #1

    It doesn’t really matter if heat gets trapped, moisture is really the only concern, and with the relatively small area above that beam also being pretty well sealed up by the spray foam on either side, I doubt there is much possibility for moisture to get up there to cause problems. If you’re worried, you could always cut in a ridge vent just for that small space, and the ridge vent alone in this case will provide plenty of ventilation for that tiny enclosed space above the ridge beam, even without any separate intake vents the way you’d normally have with soffits for a vented attic.


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