How To Correctly Build A Roof With A Valley

Up from the valley center.

How to correctly build a roof with a valley. Make sure they are properly formed. Then starting at the base of the valley center your first piece of flashing in the valley. Because most framing lumber is not perfectly straight i check each piece and mark the crown before i start cutting the lumber into rafters. Keeping all of the crowns pointing up prevents waves from marring the finished roof.

Re lay the shingles you removed from the existing roof. Ensure ice and water protector has been installed along the valley first. It is important to get the roof construction correct at the valleys. For example install valley boards flush with the rafters not on top.

The valley rafter is marked for a 12 in 17 pitch and then cut with a double bevel to fit into the ridge intersection. Bed the end of each shingle in a 2 in wide ribbon of roofing cement placed 4 in. Shingle the addition roof letting the new shingles fold through the valley center and onto the old roof deck by at least 1 ft. To secure the roof valley flashing nail it down carefully.

Cut two rafters with a circular saw to the pitch of the addition roof and nail them across the rafters on the old roof.