You’ve probably heard your roofer mention valleys when discussing your home’s roof. But what exactly is a roof valley, and why do you need one?
Every roof needs some drainage system, or in other words, a way to allow water to flow off the structure. One such method is the “valley,” where two roof pieces join together (typically forming an inverted V).
The valleys on your roof are meant to divert rainwater that comes down the roof’s slopes and directs it into the gutter, which then takes it away from your house.
There are two different types of valleys: open and closed. Both can help water run off your roof, but they are created differently.
Roof Valley Types: Open And Closed
Valley shapes vary depending on where your home is located in Dayton, OH. There are open valleys and closed valleys, but both types of roof valleys serve the purpose of allowing water to properly run off your roof. The distinction between open and closed comes in when they affect energy efficiency and downspout drainage.
Open Valley Roof:
An open-style valley is used for metal roofs and does not allow air transfer to the exterior side of your roofing material.
For instance, houses in cooler climates or higher elevations are more likely to benefit from open valleys. Of course, water will still drain off the roof either way, but you use an open valley when the pitch of your roof is so steep that water runs away quickly even without asphalt shingles or non-asphaltic material in place.
Water will run down the roof, come off one of the edges rather quickly and flow around both sides of the valley. If you don’t have an open valley, water can accumulate on either side. First, it may get under your shingles, which causes leaks. Then it can also get behind your drip edge and under your roofing felt.
Benefits Of An Open Valley Roof
- The exposed metal in an open valley roof can increase the aesthetic and weather resistance.
- This makes shingle installation easier.
- They are resistant to water and weather conditions.
Closed Valley Roof:
Closed valleys – sometimes called “vented” – are built for asphalt roofs and allow air to escape from the gutter and through the valley itself.
If you live in warmer climates or where heavy rainfall is common, closed valleys can help prevent ice damming—a buildup of ice along the eaves that prevents water from draining off your roof properly.
When cold weather comes around, you don’t want any water sitting along your lower roof edge. That warm air can get trapped between the shingles and underlayment in the valley. The only way to fix it is to remove all the snow with a shovel or snow blower.
Benefits of a Closed Valley Roof
- The cost of a closed valley roof may be slightly lower.
- If the valley angles are steep, a closed valley roof can be difficult to install.
- This mixes in with the remainder of the roof’s open valley.
The best choice: It’s up to you
When it comes down to choosing between open and closed valleys, we recommend you do your research and talk to your contractor to see what’s right for you.
The 2 major considerations are energy efficiency and downspout drainage.
For thermal performance, metal roofs perform best with open valleys. Closed valleys don’t allow heat transfer through the roofing material; however, they’re better at preventing ice-damming.
Asphalt roofs tend to work well with closed valleys because of the better ice-dam protection.
The best way to determine which type of roof valley is right for your home is to consult with a roofing contractor. They can help you make an informed decision based on your particular needs.
All Around Roofing, Siding & Gutters are always open to answering any questions or concerns you may have regarding your roof valley or roof. In addition, if you would like to schedule a free estimate with us, please call (937) 902-2839, and we’ll be glad to help!