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