Quote:
Originally Posted by skidderman
Are you suggesting that if one had a perfect seal then air circulation is not required? Was told that as well but don't know what to think.
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I do not have a technical knowledge of sprayfoam insulation, so I would not want to speak with too much confidence. My understanding is that spray foam, like foam paneling, is totally sealed with no internal airspace so condensation cannot form inside of it.
Batt insulation on the other hand is full of air space so condensation is a risk and needs to be allowed to breathe. As it is sealed on the inside with vapor barrier, the outside cannot be flush against a roof because unlike tyvec the roofing materials do not breath. With the roof you also get the risk of ice dams depending on the construction and need that air flow.
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