In addition it is important to avoid nailing the shingles through the valley metal.
Roof valleys metal or shingle.
These items can be fabricated in many different profiles.
Roofing shingles are installed then cut and sealed where they overlap the metal channel.
A chalk line is then used to strike a line from the top of the valley to the bottom of the valley.
The metal is usually pre painted to best complement the shingles color blend.
For an open valley a sheet of metal usually steel sometimes copper is fastened to the roof deck.
Whether for slate shingle or metal roofing valley flashing adds detail and helps to direct water.
With an open valley a strip of metal will be visible on the roof wherever two opposing roof planes meet.
Some homeowners do not like the look of open valleys while others feel the metal accentuates the roof s shape particularly if copper or painted flashing is used.
That flashing is left exposed so the roof has visible lines of metal running down the valley.