Flashing Leaks: A Very Common Roof Leak

A small strip of metal can let a lot of water into a house. Here is why flashing fails and how to fix it.

What Flashing Does

Flashing is the metal that seals roof joints, where the roof meets a wall, chimney, vent or skylight, and in the valleys. It directs water over the roofing and away from the seams.

It must overlap correctly with the shingles to work.

How It Fails

Wind bends and lifts it. Metal rusts. Old tar and caulk dry out and crack. Poor installation leaves gaps from the start.

Once the seam opens, water runs behind the shingles.

A Lasting Repair

The fix is new metal tucked under and over the roofing layers, with sealant at the right places. Caulk alone is temporary.

A roofer water-tests the repair and checks the shingles around it.