ridge vent

[astidham]

I have put a 12' ridge vent foam roll in the center of my roof.
I have not cut the felt back in this area and was wondering, could i just put a slit in the felt for the heat to escape? I will be installing soffit vents

[dug]

There is a formula for the recommended vent area. I can't find it but it is somewhere on the forums here, I think Mt. Don might have provided it.

I seem to remember that I ended up with about 7 or 8 sq. inches per 24 in. spaced bay, around the bottom end of what I needed (I think, don't quote me!). I thought you needed at least the same amount at the top exit so you might need to make a little wider slit.

I worried about insects making a home out of the vented areas so I tacked down some screen there, but I worry about a lot of things that probably don't matter.

[astidham]

Thanks dug

[MountainDon]

According to the IRC, Section R806, the minimum total vent area is 1 sq ft of vent area per 150 sq ft of the area. There are ways to reduce that given in the same section.

[John Raabe]

See if this link to a Fine Homebuilding book on Roofing and Flashing works...

http://books.google.com/books?id=uiEDP_VVEHEC&pg=PA53&dq=venting+cathedral#v=onepage&q=venting%20cathedral&f=false

[astidham]

Thanks Don, and John.
I have a ~2" gap under the felt at the ridge.
I can cut away all the felt in that area.

[Don_P]

That 2" gap is what I typically shoot for up top. I don't think a slit will let enough moisture out.

[astidham]

Thanks for the input Don_P