Recommended procedures of basic valley flashing installation.
Metal roof w valley installation.
Best practices for sealing the metal roof valley vary based on the slope of the roof.
Shingle the other side of the valley the same way.
Install synthetic roofing underlayment or felt paper according to manufacturer specifications and then install the first piece of valley flashing.
Install an underlayment centered in the roof valley.
Then install a non corrosive metal valley flashing of 24 minimum width.
W type valley flashing is more rigid for handling so it stays straight and it stops waler rushing down one side of a roof from rushing back up the other side.
Stop nailing 6 inches from the center.
Cut the panels from the ground instead of on the roof to avoid damaging the roof with the debris.
Allow w valley trim flashing to overhang roof edge so it can be trimmed back flush with roof overhang.
Starting at the bottom fasten w valley trim flashing to purlins or substrate using 1 1 4 roofing nails 1 from trim edge every 24 on center.
Snap a chalkline 2 to 3 inches past the valley center on the top layer of shingles.
Lap successive sheets of metal flashing a minimum of 12 inches and seal laps.
Low slope roofs slope less than 3 12 use tape sealant between the valley trim and the panel.