Flashing seals up the space between the roofing shingles and a neighboring structure, like the chimney or a roof vent. Flashing doesn't always last as long as the main roof, so it's important that you know the symptoms that it is failing.
1. Visible Rust
Roof flashing is typically made from rust-resistant metals, like aluminum, but that doesn't make it immune to rust and corrosion. Constant exposure to moisture and the elements can cause oxidation to occur, which means rust will set in. You may notice discoloration first, or the metal may begin to look like it is flaking or developing pinprick holes. Once flashing begins to degrade in this manner, replacement is the only option.
2. Warps and Bends
Warping and similar damage have several causes. Dents are typically a result of trauma, often from hail. Waves across the length of the flashing can be the result of a manufacturing defect on new flashing or simple age on old flashing. Curling and pulled up edges are typically caused by wind. Regardless of the type of warp and what caused it, the flashing will need to be replaced if it shows any of this damage.
3. Missing Pieces
It can be easy to overlook a length of missing flashing until after the leak begins. Get in the habit of glancing at your roof after any major storm or following windy weather. Look around the base of the chimneys, vent stacks, and along the valleys and ridges. If you see any damaged or missing flashing, schedule a prompt repair so you can have the area sealed before a leak causes damage to the interior of your house.
4. Failed Sealants
Flashing isn't simply nailed into place. The edges and sometimes the entire surface of the metal is covered with a sealant. This sealant is typically made of some sort of silicone caulk or roofing tar. Over time, the sealant will age and begin to crack or peel. When this happens the flashing is more prone to damage and leaks are more likely to occur. If you notice that the sealant is failing, you can have it reapplied so that the life of the flashing is extended.
5. Neighboring Shingle Damage
Sometimes you don't see the flashing damage right away, especially if the surface looks fine and water is instead seeping beneath the flashing. In this case, the first symptoms may appear on the shingles bordering the flashing. If they look darker than the rest of your shingles, are beginning to curl, or have lost a lot of their surface granules, both the shingles and the flashing will need to be replaced.
Contact a roofing repair service in your area for more assistance with any flashing issues.