Recommended procedures of basic valley flashing installation.
Metal roof w valley installation.
Shingle the other side of the valley the same way.
Snap a chalkline 2 to 3 inches past the valley center on the top layer of shingles.
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.
Roof one side of the valley running the shingles across it.
Install synthetic roofing underlayment or felt paper according to manufacturer specifications and then install the first piece of valley flashing.
Stop nailing 6 inches from the center.
Then install a non corrosive metal valley flashing of 24 minimum width.
Install an underlayment centered in the roof valley.
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.
How to seal metal roof valley.
Lay one and two tab shingles as you near the valley so full size shingles will run across the valley.
Low slope roofs slope less than 3 12 use tape sealant between the valley trim and the panel.