When homeowners think “roof leak,” they often picture missing shingles. But in many real-world cases, shingles are fine—the leak comes from flashing: the metal (and membrane) details that connect the roof to walls, chimneys, skylights, and valleys.
This guide shows what flashing does, where it fails, and what a lasting repair typically involves.
What is roof flashing?
Flashing is a waterproof transition system. It’s designed to prevent water from entering at roof joints and changes in direction where shingles alone cannot reliably seal.
Common flashing types (and where they’re used)
- Step flashing: where roof meets a sidewall (common on dormers and second-story walls).
- Counter flashing: often used with masonry or stucco interfaces.
- Valley flashing: where two roof planes meet and concentrate water.
- Apron flashing: at the front/base of a wall or chimney.
- Drip edge: at eaves/rakes to guide water into gutters and protect edges.
How flashing fails
- Improper layering: flashing not integrated with underlayment and shingles.
- Fasteners in water paths: nails/screws placed where water runs.
- Sealant-only “repairs”: temporary fixes that crack under UV and movement.
- Corrosion or fatigue: older metal can develop pinholes or separation.
Signs of a flashing-related leak
- Leaks during wind-driven rain (not every storm).
- Staining near chimneys, skylights, and wall intersections.
- Interior water lines that appear offset from where you assume the leak is.
What a durable flashing repair looks like
Lasting repairs usually involve rebuilding the flashing layers—not smearing more sealant. The exact solution depends on the roof material and the detail, but generally includes removing enough roofing to correctly integrate new flashing.
Need leak repair?
If you suspect flashing issues, start with a roof-level inspection and a clear repair plan. Visit roof repair or contact us. If water is actively entering, consider emergency service.