What are the Differences Between Closed and Open Valleys?

Republic Roofing’s damage repair specialists explain what are the differences between closed and open valleys.

• Closed Valleys 

The roofing contractor applies an underlayment over the whole roof deck before installing a shingle roof. You may include a self-adhering ice and water shield or another form of underlayment. This layer is thicker than the underlayment that covers the rest of the roof system. This self-adhering underlayment forms the valley lining.

The roofer will put the shingles onto the roof deck and extend the asphalt shingles across the area where opposing roof planes meet, covering or “closing” the valley area. When done, the asphalt shingles will cover the valley and the self-adhering underlayment. So, the asphalt shingles function as the valley lining and the water-resistant wear surface.

• Open Valleys 

An open valley, as opposed to a closed valley, offers an additional layer of lining to the valley. Following the installation of the self-adhering underlayment over the valley, a pre-bent metal valley lining is fitted. Manufacturers can make this valley flashing material from any metal resistant to weather, acid rain, and other pollutants. Galvanized steel, aluminum, and copper are all acceptable materials.

The asphalt shingles are installed on the roof deck. However, these shingles do not cover the valley region completely. Your roofer will leave the center of the metal valley visible. Furthermore, it is critical to prevent nailing the tiles through the valley metal. Then, a chalk line is drawn from the top to the bottom of the valley. The shingles are then removed from the valley area, “opening” the valley lining’s surface to water run-off and the environment. An open valley will have a strip of metal visible on the roof where two opposing roof planes meet.

When Is It Better to Choose a Closed Valley Over an Open Valley?

Contractors and homeowners may opt to build an open valley or a closed valley for a variety of reasons, including:

• Aesthetics: Contractors, designers, and owners have preferences for one style of the valley over another. It is critical to note that a closed valley hides the valley line and allows the roof planes to merge. On the other hand, open valleys expose the metal, which may be more visually appealing if you use copper as the valley lining.
• Cost: By removing the metal laid in valleys, contractors can minimize the cost of materials for roofing projects. This will lower the project’s installation cost, especially if the roof has many valleys.
• Utility: The functionality of closed valleys vs. open valleys differs according to installers and designers. Closed valleys conduct water under the shingles placed over the bottom layer of shingles if not built appropriately. However, if open valleys are not correctly trimmed, water might back up over the top of the cut-off shingles, leading to roof leaks.

When upgrading the roof system on your home or structure, assess both solutions. Likewise, if you decide to do your roof replacement yourself, consider these variables before beginning your project. 

If you hire a professional roofing contractor to replace your roof, clarify how they will handle the valley aspect. Addressing the valley detail before construction begins allows you to evaluate the options and achieve the look and functionality you need on your roof.

Specialists Will Help You Choose the Right Type of Valley for Your Roof

Republic Roofing, your top specialist for residential and commercial roofing services, can help you narrow down your search for roofing and gutter businesses. 

For more than 20 years, Republic Roofing in Tennessee, has been providing commercial and residential roofing services to companies and residents in the area.

For more information, contact Republic Roofing at 901-437-5278. We service areas in Lakeland, Germantown, Bartlett, Memphis, and Collierville, TN.