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 cut valley roofing.
For an open valley a sheet of metal usually steel sometimes copper is fastened to the roof deck.
Open valleys may be susceptible to water backup if the cut off shingles are not properly trimmed potentially causing roof leaks.
The closed cut valleys are cheaper and commonly done in my area but they tend to wear out sooner due to the high volume of water in the valley washing away the protective grit on the shingles there before on the rest of the roof.
Install synthetic roofing underlayment or felt paper according to manufacturer specifications and then install the first piece of valley flashing.
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Fold the top over the roof ridge and cut the bottom along the drip edge metal.
The valley lining whether asphalt or metal should have 6 inches open at the top 3 inches on either side of the valley centerline and increase by 1 8 inch for each foot of valley length to accommodate the greater flow further down the valley.
If homeowners are looking to have their roof last for many years an open valley is iko s recommended choice and a good up sell opportunity for the roofing professional.
Jb wholesale roofing and building supply has 8 locations to serve everything you need for your roof whether residential or commercial.
I m leaning towards an open metal valley but i ve had contractors disagree saying that the metal expands.
For an open valley the installer should snap two chalk lines defining the cut edges of the valley on either side of the center line.
Roofing shingles are installed then cut and sealed where they overlap the metal channel.
The metal is usually pre painted to best complement the shingles color blend.
A basic demonstration for roofing contractors and homeowners on how to install gaf timberline shingles using the closed cut valley method.
With an open valley a strip of metal will be visible on the roof wherever two opposing roof planes meet.
As another benefit to the roofing professional open valleys are sometimes used to easily bridge the gap between roof faces of vastly different pitches.
When to choose a closed valley over an open valley.
The underlayment sheet metal liner if required and initial shingle covering into or through the valley follow the same guidelines for the standard closed cut valley and open valley construction.