Open Or Closed Roof Valley

The metal is usually pre painted to best complement the shingles color blend.

Open or closed roof valley.

Open valleys may be susceptible to water backup if the cut off shingles are not properly trimmed potentially causing roof leaks. A closed valley is where the tiles or shingles are butted up against each other in the center of the valley. For an open valley a sheet of metal usually steel sometimes copper is fastened to the roof deck. Closed valleys may have a tendency if not constructed properly to channel water under the shingles laid over the bottom layer of shingles.

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. Although the open valley is recommended by the manufacturer closed valley is acceptable. 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. The roofers apply the shingles cutting and sealing the ones that overlap the metal.

The only type of valley that is unacceptable is the woven valley. Open valleys are excellent for preventing moisture from entering through the lining and protecting your roof from the humidity of the outside air. Closed valleys protect the roof lining from abrasion that water run off would cause and are therefore quite durable options. 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.

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. 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. 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. 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.

An open valley can easily and quickly shed ice and water. It is always a good idea to check with the manufacturer or a certified installer of the product such as ourselves.