A valley is where two roof surfaces meet. It’s also considered one of the leak-prone areas of the roof. It creates a channel that lets moisture to run down the roof. Metal sheets or roof rolls are placed over them to prevent water penetration.
Find out the difference between open and closed valleys from a trusted residential roof installation expert.
Closed Valley
Before shingle installation, contractors install an underlayment over the roof deck. A self-adhering ice and water shield may be integrated into the underlayment. It can also be another kind of underlayment with a heavier gauge than the underlayment that lays on the rest of the roofing system. Moreover, the self-adhering underlayment is considered the valley lining.
In a closed valley, roofers will install the shingles onto the roof deck and extend the shingles through the valley. As a result, shingles conceal or close the valley area. After the roofing installation, the valley and self-adhering underlayment will be covered with asphalt shingles.
Open Valley
Meanwhile, in an open valley, another layer of lining is added to the valley. A pre-bent metal valley lining is installed after the self-adhering underlayment. This valley material can be made from any metal that resists acid rain, weather, and other harsh outdoor elements.
Shingles are extended into the valley as they are installed over the roof deck. However, they aren’t run through the valley area. It’s also important that the shingles aren’t nailed through the valley metal. Roofs usually use a chalk line to strike a line from the valley’s top to its bottom. After this, the shingles are cut out of the valley, opening the surface of the valley to water run-off.
At State Roofing & Exteriors, you can count on us for asphalt and metal roofing needs. Give us a call at (360) 794-7164 or fill out our contact form to schedule a free estimate. We serve clients around Seattle, WA.
