Direct Answer
Roof flashing is the thin metal (or sometimes rubberized) material that seals the joints and transitions where the roof is interrupted — around chimneys, walls, valleys, skylights, vents, and pipe penetrations. Flashing is what keeps water out at the spots where shingles alone can't. Most roof leaks are actually flashing failures, not shingle failures.
Shingles shed water down the slope, but every place the roof is interrupted — a wall, a chimney, a valley, a pipe, a skylight — needs flashing to direct water away and seal the joint. Flashing is the unsung hero of a watertight roof.
Common Types of Flashing
- Step flashing — interweaves with shingles where a roof meets a wall
- Valley flashing — lines the troughs where two roof slopes meet
- Chimney flashing — step flashing up the sides plus counter-flashing cut into the mortar
- Drip edge — metal at the roof edge that directs water into the gutters
- Penetration flashing — around vents, pipes, and skylights
Why Flashing Fails
- Sealant at flashing edges dries out and cracks
- Flashing lifts, loosens, or pulls away from the surface
- Poor installation (wrong overlap, missing pieces, inadequate sealing)
- Wind or storm damage bends or peels flashing back
Signs & Symptoms
- Water stain near a chimney, wall, valley, or skylight
- Visible lifting or gaps at flashing edges
- Dried or cracked sealant at flashing joints
- Leak during wind-driven rain
Repair Options
- Re-seal flashing edges (temporary)
- Re-flash the failing area with new metal (lasting)
- Re-flash a chimney with new step and counter-flashing
- Replace valley or skylight flashing
When to Call a Roofer
Any leak near a chimney, wall, valley, or penetration is likely a flashing issue. Get it inspected and repaired at the source before water causes interior damage.
How Beyond the Ladder Handles It
We install and repair flashing properly — step, valley, chimney, drip edge, and penetrations — so water is directed away from the joints that leak most.
Related Questions
Is flashing the most common cause of roof leaks?
Yes. Most leaks that aren't a cracked pipe boot come from failed flashing at a chimney, wall, valley, or penetration. Shingles rarely leak on their own — the joints do.
What material is roof flashing made of?
Most commonly aluminum, galvanized steel, or copper. Each has different durability and cost. Copper lasts longest; aluminum is most common for residential work.