How To Flash A Roof Valley

Remember to caulk the underside of the flashing with a sealant.

How to flash a roof valley.

Snap a chalkline 2 to 3 inches past the valley center on the top layer of shingles. Attach the flashing panel in place at the bottom. Lay the flashing down in the roof valley and start at the lower end of the roof. Lay one and two tab shingles as you near the valley so full size shingles will run across the valley.

Make sure to cover the gap at the bottom of the raised ridge. Cut the bottom edge and fold it down over the drip edge. Two ways to flash roof edges. Step 6 install the flashing.

Make sure that the end of the flashing panel is perfectly in line with the edge of the roof. Stop nailing 6 inches from the center. One common method is to lay the edge metal under the eaves membrane and over the rake. Install valley battens on both ends of the roof valley then attach first flashing 3 4 inches over the roof flange and another 3 4 inches over the fascia if any is present.

Now nail this first flashing at both its far ends. Use 1 inch galvanized roofing nails. Fold the top of the flashing over the ridge. To splice the pieces add roofing cement to the lower piece and install the upper piece with at least a six inch.

Roof one side of the valley running the shingles across it.