Roofing/Ridge Vent


QUESTION: We had a new asphalt shingle roof installed about 7 years ago and the contractor also installed a ridge vent.  When I look at the peak from inside the attic, there is a gap of about 3 or 4 inches between the plywood sheathing on one side of the house to the other.  This gap is covered by the ridge vent, which has a mesh fabric liner on the underside.  But the felt paper and shingles on top of the plywood sheathing and underneath the ridge vent block all but about 1 inch of this gap. From inside the attic, should I score the felt paper and shingles and snap them back to the edge of the plywood so the full gap is exposed, thus increasing my free area?  Or would this cause some problem?  Thanks!

ANSWER: Do you know if you have a ridge beam going across the top of the roof or is the structure made out of trusses?


---------- FOLLOW-UP ----------

QUESTION: There is no ridge beam.  The structure is made of trusses.

That means that there is no ridge beam blocking the opening so the cut-out area is smaller. You need about 1" on each side. Since there is no ridge beam the 1" starts in the center for a total of 2". If you already have it leave it alone. If not you can cut back a little on each side. Be careful that the ridge vent comes down far enough to do this. The ridge vent should come onto the shingles a few inches. The steeper the roof the more you can get away with here. Increasing the opening will do little unless you have intake vents to match the same area.



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Brad Zacharia


All aspects of residential Roofing. This includes shingles and flat (low slope) roofs. I have knowledge in the installation as well as the design of roofs from an engineering standpoint.


I have been doing roofing for 40 years. This was my father's business and I took it over in 1980.

I have written responses to artcles that I felt needed a response to and those responses have been published in roofing trade magazines.

BSEE Drexel University

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