What Is Roof Flashing and Why Does It Fail?

Flashing is the metal layer placed where your roof meets walls, chimneys, vents, and valleys. Its job is to create a waterproof barrier, guiding rainwater and melting snow away from seams that would otherwise leak. Without flashing, those joints become entry points for moisture.

Think of flashing as a shield for the most exposed parts of your roof. It works with your shingles, not against them. When flashing is intact, water flows over it and down the slope. When it fails, water finds the gap and starts working its way into your attic and walls.

Look for water stains on ceilings or walls, especially near exterior corners or along the roofline. You might also notice peeling paint or damp spots in the attic. Check the flashing itself if you can safely see it from the ground or a ladder, looking for rust, gaps, or lifted edges.

Another sign is a musty smell in the attic, which suggests moisture is accumulating. If you see daylight through the roof joints from inside the attic, that is a clear indicator flashing has shifted. Acting quickly when you spot these signs can limit the spread of water into your home's structure.

You can reduce flashing failures by having your roof inspected after major storms and at least once a year. Keep gutters clear so water does not back up under flashing. Trim overhanging branches that could scrape or drop debris onto the roof.

If you spot a problem, do not wait. Small leaks become big ones quickly. For interior water damage, you may need professional drying to prevent mold and structural issues. Check your insurance policy to understand what is covered, and keep records of any repairs. Policies vary, and your insurer decides what is covered.

• Inspect flashing after storms
• Clean gutters to prevent water backup
• Trim branches near the roof
• Look for stains or musty smells in the attic
• Act quickly if you suspect a leak