How To Install A Metal Roof Valley Flashing

Shingle the other side of the valley the same way.

How to install a metal roof valley flashing.

Use 1 inch galvanized roofing nails. Attach the flashing panel in place at the bottom. Then install a non corrosive metal valley flashing of 24 minimum width lap successive sheets of metal flashing a minimum of 12 inches and seal laps. Snap a chalkline 2 to 3 inches past the valley center on the top layer of shingles.

Use fasteners to attach the panel to the structure making sure that there is complete compression of the sealant. Lay the flashing down in the roof valley and start at the lower end of the roof. First clean the debris out of the valley including sawdust nails and whatever else is in there. The top joinery of both valleys when they meet on the same plane of roof is shown here.

Install an underlayment centered in the roof valley. Fold the top over the roof ridge and cut the bottom along the drip edge metal. Roof one side of the valley running the shingles across it. I have my valley custom made with water trough to help with leaking b.

Make sure that the end of the flashing panel is perfectly in line with the edge of the roof. Low slope roofs slope less than 3 12 use tape sealant between the valley trim and the panel. Lay one and two tab shingles as you near the valley so full size shingles will run across the valley. Apply an approximately 3 inch width of asphalt roofing cement along the sides of flashing and embed shingles in mastic.

Stop nailing 6 inches from the center.