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metal roofs and spray foam ?
Do i need to vent my cathedral ceilings if i sprayfoam the roof trusses 100% ?
or do i need to create an air cavity above the spray foam , such that the air above it needs a soffit and a ridge vent ?
i have one roofer whom says: i have never had to vent a sprayfoam cathedral before
but the CMHC (Canadians) says that we should vent it .
Other: i must admit... if i were using shingles... this would be necesary to increase the longevity of the roof.
Also: if i were to use bafflels / pink insulation bats soffits, air space and vents are a MUST.
input please ?
thanks
DON..... METAL roofs ! Not Shingles. I understand the venting for shingles.... but for metal roofs and cathedral ceilings with Spray foam. Why is the industry split on putting an air passage?
2 Answers
- Anonymous9 years agoFavorite Answer
The increased heat will not damage the roof. Building codes however say that there must be a minimum one inch vented airspace. However, buildings are built all the time without the vented airspace. As long as the foaming is done properly, I have no problem with installations that do not have an airspace. I hope this helps. 30 years metal roofing industry experience.
Source(s): Www.asktoddmiller.com Www.classicroof.com - 9 years ago
As a rule of thumb there should be air flow in the space below the roof. When the sun beats down on dark shingles they get very hot. Having air flow allows the heat to escape. If shingles get too hot they will curl up shortening the life of your roof substantially.