Closed Vs Open Valley Roof

The exposed metal lining can serve as an architectural feature on your roof.

Closed vs open valley roof.

On a closed valley roof the shingles extend to the valley area completely closing it off. Thus closed roof valleys extend the time between your roof repair projects. A closed valley is where the tiles or shingles are butted up against each other in the center of the valley. Designwise an open valley roofing system would be probably more appealing.

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. 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 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. For an open valley a sheet of metal usually steel sometimes copper is fastened to the roof deck.

The metal is usually pre painted to best complement the shingles color blend. Installer s and designer s opinions differ as to the functionality of closed valleys versus open valleys. 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. Roofing material manufactures or roofing associations may have recommended installation guidelines for their products or for various roofing materials.

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. Open valleys may be susceptible to water backup if the cut off shingles are not properly trimmed potentially causing roof leaks. Shingles may crack when being manipulated around the valley. Meanwhile on an open valley roof the metal lining that prevents water from seeping into the underlayers is left exposed.

An open valley has a gap usually about 6 inches between the tile or shingles at the valley area. Ultimately laying any shingle in a valley can restrict proper water and debris flow unlike the metal flashing used in an open valley. The shingles in the valley may lose their granules and thus their coloration and protective capability faster than the rest of the roof. It s also less susceptible to water damage as the shingles will naturally channel water away from the roof.

It depends on your needs and preferences. A variation of closed cut valley. What s the difference between a closed and open valley roof. Another consideration is the outdoor temperature.

I would probably say go with the open valley if your roof is being installed in colder temperatures.