Open Or Closed Roof Valley

Although the open valley is recommended by the manufacturer closed valley is acceptable.

Open or closed roof valley.

An open roof valley meanwhile is a flashing method in which a sheet of pre bent metal is installed after the valley lining is placed. Closed valleys are very vulnerable to mechanical damage. 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. Open valleys are excellent for preventing moisture from entering through the lining and protecting your roof from the humidity of the outside air.

The only type of valley that is unacceptable is the woven valley. The metal is usually pre painted to best complement the shingles color blend. However open valleys may be susceptible to water back up along the top of the cut off shingles in the valley if not properly trimmed potentially causing roof leaks. The main advantage of closed valleys is that they protect the roof from snow and ice build up however in florida this is not an issue that needs to be considered.

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. A closed valley is where the tiles or shingles are butted up against each other in the center of the valley. Closed valleys may have a tendency if not constructed properly to channel water under the shingles laid over the bottom layer of shingles. If you have a shingled roof as most torontonians with a sloped roof tend to have then you will have one of two kinds of valleys on your home.

Closed valleys protect the roof lining from abrasion that water run off would cause and are therefore quite durable options. An open valley has a gap usually about 6 inches between the tile or shingles at the valley area. However it is said that provided the rest of the roofing shingles were properly installed and are performing properly open valleys will perform better over time than closed valleys. Open valleys may be susceptible to water backup if the cut off shingles are not properly trimmed potentially causing roof leaks.

An open valley can easily and quickly shed ice and water. For an open valley a sheet of metal usually steel sometimes copper is fastened to the roof deck.