An Open or Closed Case for Roofing Valleys?

Professional contractors know that one of the most vulnerable areas of any roof is the valley, where the roof’s planes intersect. If not properly protected and sealed, a valley can channel water directly into the home with potentially disastrous consequences. There are two very popular types of roof valley construction methods used among contractors today, each with their own advantages and disadvantages.

Closed valleys have become popular among contractors for their aesthetic qualities as well as the ease and speed of installation. They don’t require additional materials to install or the number of extra steps that an open valley requires. For a closed valley, shingles are installed across the joint where planes intersect. With each new course, roofing shingles continue up the valley.

According to long-time IKO sales representative Jeff Tessaro, closed valleys for residential construction have been popular since he was a roofing contractor in the late 90’s. “Residential roofs still tend to favor closed valley systems because they’re more cost-effective, and the contractor already has the needed materials on-hand,” Tessaro says.

However, Tessaro points out that in a closed valley system, ice and water aren’t shed as quickly and the continuous build-up and channelling of water during storms may result in granule loss. 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.

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. Roofing shingles are installed then cut and sealed where they overlap the metal channel.

“Provided the rest of the roofing shingles were properly installed and are performing properly, my experience has been that an open valley system holds up better over time,” Tessaro says. He notes that due to the metal construction of an open valley, it may shed ice and water more quickly, which could help minimize granule loss. Installed correctly, it provides a unique aesthetic, especially when using painted or copper coil stock. “And, if problems with roof leaks or other damage occur years later, an open valley system is often easier to repair or replace,” says Tessaro.

These are reasons why the IKO’s application instructions recommend open metal valleys for best performance.

Tessaro says, “Homeowners understand the importance of choosing the right shingles. Color, performance, value and limited warranty are factors they consider, but very few know about open versus closed valley applications. This offers contractors a significant opportunity to educate the homeowner and position the open valley as an upsell option.”
Tell us what your experience is with open versus closed valley applications.