Valleys are a common roofing feature, and they're inevitable whenever two different sections of your roof intersect. They collect quite a bit of water due to water from two roofing sections flowing into them, but they usually don't pose a problem for your roof. When a valley doesn't drain properly, however, it's referred to as a dead valley, and they can cause major damage to your roof.
Dead valleys can occur when two downsloping roof sections intersect, creating a very flat valley between them. They can also occur when a downsloping roof section intersects with a second-floor exterior wall. Since they don't drain very well, dead valleys accumulate ponding water. Standing water will quickly cause major damage to most types of roofs, so you'll rapidly develop a leak in your roof.
If your roof has a dead valley, you'll need to have it reinforced in order to prevent a leaking roof and the water damage that can ensue. To find out how to tell if your roof has a dead valley and how you can stop it from damaging your roof, read on.
How Do You Know if Your Roof Has a Dead Valley?
When you have an area on your roof that collects small leaves and other debris, it's likely a dead valley. When a roof slopes properly, rainwater will push leaves off of your roof. Since a dead valley has a shallow slope, it will collect leaves just like a gutter. You can use a pair of binoculars to examine your entire roof from the ground, which will allow you to see any areas that are collecting leaves.
Why Does a Dead Valley Cause Damage to Your Roof?
A dead valley will collect ponding water, and the leaves that collect there will also trap moisture against the roof when they get wet. Shingle roofs aren't meant to withstand these levels of constant moisture. They rely on a steep slope to shed water quickly. When water collects on a shingle roof, the shingles quickly deteriorate. After several years, water will begin to seep through the damaged shingles. The wooden decking underneath of your shingles will eventually begin to rot, which will cause major structural damage to your roof.
How Can a Roofer Stop a Dead Valley From Damaging Your Roof?
One method that can be used to prevent a dead valley from damaging the shingles is to install a copper pan in the valley. Copper doesn't rust, so it's not harmed by moisture or ponding water. Installing copper all along the dead valley will protect the shingles underneath. As an added bonus, copper pans are also quite visually appealing when they're installed on your roof.
Unfortunately, copper is very expensive. As a result, copper is only suitable when the dead valley is very small. If you need to protect a larger area of your roof, then a roofing contractor can install a single-ply membrane in the area, such as PVC. Single-ply membranes are very water-resistant, which is why they're commonly used in flat roofs. Flat roofs don't shed water as quickly, so the added water resistance is necessary.
The single-ply membrane can fully adhere to the shingles, and it will protect them from water damage once it has been installed. One downside of using a single-ply membrane is that they won't match the rest of your roof, and they don't look as good as a copper pan. However, a roofer can cover the single-ply membrane up by adhering roofing shingles to it. The shingles will deteriorate due to the ponding water, but the damage won't lead to your roof leaking—your roof is relying on the single-ply membrane for protection.
If your roof has a dead valley, contact a roofing service in your area and have it inspected. Whether you choose to protect your roof with a copper pan or a single-ply roofing membrane, you'll prevent the dead valley from causing extreme structural damage to your roof. For more information about protecting your roofing materials, contact a local roofer.
