In roofing terminology, the valley refers to the straight line formed when two different roof planes meet. Homes with a T-shaped or L-shaped footprint tend to have this feature as well as homes with gable dormer roofs. The valley is also the most vulnerable part of the roof, which is why flashings are installed on top of it so that water gets channeled safely from two opposing roof planes to the gutters at the edge of the roof.
If you are looking to invest in a new roofing system, you’ll have to decide what method of flashing to consider for this crucial roof component. Here are the differences between closed and open roof valleys.
Steps Taken During Installation
To better understand the two methods, it is worth discussing how roofers prepare the would-be valleys of the roofing system. Before they assemble the roof covering, they first install an underlayment over the entire roof decking or sheathing. Then, they apply either a self-adhering ice and water shield or another underlayment with a heavier gauge that will serve as the valley lining.
About Closed Roof Valleys
A closed roof valley is a flashing method in which the installation of the roof covering is extended to where the two opposing roof planes meet. This “closes” the entire valley area, with the self-adhering underlayment layer completely hidden from view. Easier and faster to install, it is a cost-effective method because it doesn’t require additional materials. Since the area is covered by shingles, the closed valley makes the roofing system more appealing when seen from the ground.
About Open Roof Valleys
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. An open valley can easily and quickly shed ice and water. It also minimizes shingle granule loss, leading to a long-lasting look. It can have as stunning an appearance as the closed valley if done properly.
Planning to install a GAF roofing system in your home? Don’t hesitate to turn to Pritchett Bros. Give us a call at (812) 567-1266, or fill out our contact form to get a FREE roof inspection. We serve homeowners in Bedford, Bloomington and other nearby areas.