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Is air gap between insulation and roof deck needed when there is no eve vent?

mikeysp | Posted in General Questions on

Hi, in zone 4a. My son’s house. Built in 1942. Addition we are working on probably 1960s. 

There is only 2-1/2″ of space between top plate and roof deck. 

In section of roof near eve where I only have a few inches to work with, I am going to spray foam in some recycled XPS I have on hand. 

Since the eves are not vented, do I still need an air gap between the roof deck and the XPS?

The house really needs a full remodel in the next few years, but since a roof leak damaged the ceiling tiles, my son pulled them out and repaired the leak. I was thinking about a drop ceiling, but also just some strapping and a few inches of XPS for now where rafters are thin.

Thank you for your advice.


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