Venting Beneath Roof Deck
I have a detached garage in NJ zone 4a and I am going to install Tesla power wall lithium ion batteries inside as a home power backup. They prefer to operate in the range 32°F to 86°F (0°C to 30°C) .
The spray foam contractor says that I don’t need any ventilation space between the spray foam and the underside of the roof and suggests spraying directly onto the underside of the roof OSB. What is your opinion? I want to avoid ice dams and roof rot.
Dr. Joseph Lstibuerk (building science expert) seems to think that the underside of roofs need to be ventilated:
If not, would installing a product like Smart Baffles we effective even though my garage does not see to have a ridge vent? I suppose one benefit of having baffles separating the foam from the roof would be that come time to replace the roof, the roof underside won’t be stuck to the spray foam and thus break when the roof deck is removed (so I won’t need to re-insulate).
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