Open Valley Roof Vs Closed

In looking at the fabral metal roofing supply catalog it has a valley flashing that from the end looks like a w.

Open valley roof vs closed.

I further feel that an open metal valley would flush faster without wearing away the granules. After the self adhering underlayment is installed across the valley a pre bent metal valley lining is installed. Open roof valley this is almost the same as the closed roof valley method except a pre bent metal valley lining is installed instead of a secondary roof underlayment. Repairs to closed valleys are a lot more involved than working on an open valley as is re roofing or making changes to a portion of your roof in the future.

Since it isn t bogged down by the friction shingles invariably create. A closed valley is where the tiles or shingles are butted up against each other in the center of the valley. An open valley has a gap usually about 6 inches between the tile or shingles at the valley area. This leaves a metal strip or line on the surface of the roof that serves as the valley line.

The only type of valley that is unacceptable is the woven valley. After the underlayment is placed a pre bent metal valley lining is installed. The closed variation is a flashing that has been completely covered with shingles while in the open variation will have the flashing completely exposed to the elements. In comparison to a closed valley an open valley adds another layer of lining into the valley.

What is an open valley roof. Proponents of the open version say that an open flashing allows the rainwater to move away from the roof faster. For an open valley a sheet of metal usually steel sometimes copper is fastened to the roof deck. It is always a good idea to check with the manufacturer or a certified installer of the product such as ourselves.

Regardless of open or closed this of course presumes that a grace water ice membrane is used. When you research this topic online you will likely find people who prefer one of these methods of the other and they will give their reason. This metal lining can be made of any type of metal that is resistant to the effects of weather acid rain or other contaminants. Although the open valley is recommended by the manufacturer closed valley is acceptable.

And while some homeowners may prefer the aesthetics of a closed valley the heavier and thicker the shingle the less likely it is to lie flat across a joint. Once the shingles are installed they don t run through the valley area.