Open Valley Vs Closed Valley Roof

There are 2 different methods to roof valleys.

Open valley vs closed valley roof.

The shingles completely cover the underlayment and they become the valley lining itself. An open valley has a gap usually about 6 inches between the tile or shingles at the valley area. In comparison to a closed valley an open valley adds another layer of lining into the valley. A closed valley is where the tiles or shingles are butted up against each other in the center of the valley.

After the self adhering underlayment is installed across the valley a pre bent metal valley lining is installed. Find out the differences before you talk to a roofing expert. There are two methods for sealing valleys. Regardless of open or closed this of course presumes that a grace water ice membrane is used.

In closed valley applications the field shingles are installed across the valley. Open valleys refer to trimming back the shingles along the valley metal hence exposing the flashing and allow water to run off. This essentially extends the asphalt shingles through the valley so the roof surface covers or closes the valley area hence the name. I further feel that an open metal valley would flush faster without wearing away the granules.

Moving on here are a couple of things to think about when deciding open or closed. Because of the sheer amount of water being navigated through this section your valleys need to be properly sealed. Are there advantages to either application. In looking at the fabral metal roofing supply catalog it has a valley flashing that from the end looks like a w.

With each new course roofing shingles continue up the valley. For a closed valley shingles are installed across the joint where planes intersect. Open valleys and closed valleys. Valleys are created where two roof slopes meet.

Furthermore the description of the roofing company whose closed valley failed seemed to fit the profile of a fly by night roofing company and so i d have to assume that workmanship and expertise was secondary to making a quick buck. 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. What are the differences. In the closed valley method the shingles are installed onto the roof.