Intersecting Roof Valleys

Again choosing the easy way out we opted to build blind valleys aka california valleys where one intersecting roof is built on top of the other.

Intersecting roof valleys.

For roof pitches less then 6 per foot the flashing extends at least 12. Intersecting roofs using a closed valley must have the same slopes so that the shingle butts line up at the valley intersection. Stop nailing 6 inches from the center. Roof one side of the valley running the shingles across it.

An unequally pitched valley rafter is laid out in the same way as the unequally pitched hip. To splice the pieces add roofing cement to the lower piece and install the upper piece with at least a six inch overlap. The main difference between the two is that valley rafters sit on inside corners while hip rafters sit on the outside corners. The gable roof on the porch addition was framed with a dropped structural ridge supporting the common rafters above.

The diagonal rafter that runs from the intersection of the ridges down to the top of the walls at the inside. Snap a chalkline 2 to 3 inches past the valley center on the top layer of shingles. Where two gable roof lines meet the intersection forms inside corners called valleys. It s also known as a cross gable roof since the home has a cross footprint.

Interestingly you can mix and match roof styles when building a gable and valley roof designs for a cross footprint home. Lay one and two tab shingles as you near the valley so full size shingles will run across the valley. The gable and valley roof is a very popular roof design. For roof pitches of 6 or more per foot the flashing extends at least 9 under the roof covering on each side.

Shingle the other side of the valley the same way. Gable and valley roof. Fold the top of the flashing over the ridge and nail it off every ten inches or so along the outer edge of the flashing now this valley will carry water off the roof and away from the house.