Know Your Roof · Flashing & Roof Edge
Roof Flashing: Types, Materials and Common Problems
Quick answer
Roof flashing is thin metal, sometimes rubber, installed wherever a roof meets something else: a chimney, a wall, a vent, a valley. It steers water over those weak spots and away from the roof deck. A lot of roof leaks start at flashing, not in the middle of the shingles.
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Where flashing goes
Along walls and dormers (step flashing). Around chimneys (base, step and counter flashing, plus a cricket). In valleys where two slopes meet. Around pipes and vents (pipe boots). At the roof edge (drip edge). And where a roof slope runs up into a wall (apron or headwall flashing).
What it's made of
Galvanized steel and aluminum are the usual picks: durable and affordable. Copper lasts a long time and looks good, so it shows up on premium and historic work. Lead turns up on older roofs and some pipe flashings. Rubber or neoprene is common for pipe boots, and it's the first thing to crack.
How flashing fails
Rust or corrosion. Sealant that dried out and cracked, even though it was never meant to be the main protection. Metal that's come loose or lifted from wind and temperature swings. Or a bad install, like missing pieces or overlaps going the wrong direction. Cincinnati's freeze and thaw cycles move roofing materials a little every day, and that loosens joints over time.
Signs of a problem
Stains on a ceiling or wall near a chimney, dormer or vent. Rust streaks. Sealant that's cracked or missing. Leaks that only show up in wind-driven rain.
What does flashing repair cost in Cincinnati?
Most flashing problems are repairs, not replacements. Flashing repair around a wall, chimney, or valley typically runs $400 to $900. A minor repair that includes flashing, a vent boot, or one or two shingles runs $400 to $750. The final number depends on how much flashing is damaged and how hard it is to reach, and every job starts with a free roof inspection.
Looking for another word? See the roofing terms glossary, A to Z.