Closed Vs Open Valley Roof

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.

Closed vs open valley roof.

It is always a good idea to check with the manufacturer or a certified installer of the product such as ourselves. This allows water to fall from the higher slope to the lower slope and prevents it from going under the shingles to the roof deck. 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. Although the open valley is recommended by the manufacturer closed valley is acceptable.

That said an open roof valley is a good option if you want to the metal strip to serve as an architectural detail on the roof. The metal is usually pre painted to best complement the shingles color blend. When compared to a closed valley and open valley adds an additional layer of lining. Proponents of the open version say that an open flashing allows the rainwater to move away from the roof faster.

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. For an open valley a sheet of metal usually steel sometimes copper is fastened to the roof deck. Shingles are cut on the higher slope in a straight line through the valley. Since it isn t bogged down by the friction shingles invariably create.

The only type of valley that is unacceptable is the woven valley. 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. Meanwhile on an open valley roof the metal lining that prevents water from seeping into the underlayers is left exposed. Closed valleys may have a tendency if not constructed properly to channel water under the shingles laid over the bottom layer of shingles.

I prefer open valleys to let the water run out on metal. Thus closed roof valleys extend the time between your roof repair projects.