How long does roof flashing last?
Updated August 2026
Roof flashing lasts 20–50 years, but it rarely dies of old age: it fails at the seams and sealant long before the metal wears out. Aluminum and galvanized-steel flashing runs 20–30 years, copper stretches past 50, and rubberized membranes around some penetrations last as long as the roof they sit on. The catch is that flashing lives at the roof's most vulnerable joints, the valleys, chimney, skylights, and where walls meet the roof plane, so the caulk and roofing cement sealing those edges dry out and crack in 5–10 years, decades before the metal. That is where nearly every roof leak starts.
Lifespan by type and situation
| Type or situation | Typical lifespan | Why |
|---|---|---|
| Aluminum flashing | 20–30 years | Common and affordable; can corrode where it contacts other metals |
| Galvanized steel | 20–30 years | Durable until the zinc coating wears and rust sets in |
| Copper flashing | 50+ years | The premium choice; often outlives the roof and shingles around it |
| Lead or lead-coated | 50+ years | Long-lived and moldable, used on tile and slate roofs |
| Step flashing at walls | 20–30 years | Fails early if shingled over instead of woven in correctly |
| Valley flashing (open valley) | 20–30 years | Takes the most water flow, so it wears and rusts faster than field flashing |
| Sealant or roofing cement at joints | 5–10 years | The real weak link; needs resealing several times per roof life |
Signs yours is near the end
- Water stains on the ceiling or walls directly below a chimney, skylight, or roof valley
- Rust streaks, flaking, or dark corrosion visible on the metal flashing
- Cracked, shrunken, or missing caulk and roofing cement along the flashing edges
- Flashing that has lifted, curled, or pulled away from the chimney or wall
- Damp or rotting wood at the roof-to-wall joint or around a skylight frame
- Granules and rust washing into the gutter directly below a flashed seam
How to add years
Flashing is cheap to maintain and brutally expensive to ignore. An annual look, best paired with a gutter cleaning, catches lifted metal and cracked sealant while a tube of roofing cement still fixes it; inspecting the flashing each fall is the single highest-value roof habit there is. Resealing the joints every 5–10 years keeps water out of the one place a roof cannot defend itself, and letting failed flashing go turns a $200–500 repair into rotted sheathing, soaked insulation, and a four-figure interior job. If the terms trip you up, learn what flashing is and how it differs from a drip edge, the metal strip that protects the roof's outer edges. Match new flashing to the roof: copper on a 50-year roof, at minimum aluminum on shingles.
What it costs to replace: plan on $200–500 for a typical repair ($500–1,500 to reflash a chimney). Replacing on your own schedule, before it fails, is almost always cheaper than the emergency version. The home maintenance cost calculator helps you set the money aside before it comes due.
OnOtto tracks your flashing inspections age and service history, and warns you before end of life instead of after the flood.
Track your home's systems, free for 30 daysFrequently asked questions
Does roof flashing need to be replaced when I get a new roof?
Almost always, yes. Reputable roofers replace flashing during a full reroof rather than reusing it, because old flashing that has been bent, resealed, and worked around rarely seals well under new shingles, and it is a small cost next to the roof. The exception is high-end copper or lead flashing in excellent shape, which can sometimes be reused. If a contractor quotes a new roof but plans to keep the old flashing to shave the price, treat that as a red flag.
Can you repair flashing without replacing the whole roof?
Yes, and it is one of the most common roof repairs. A roofer can reseal, refasten, or swap a single run of flashing at a chimney, valley, or wall for $200–500 in most cases, far less than touching the field of the roof. Because flashing fails at the sealant long before the shingles wear out, targeted flashing repair is usually the right move on a roof with years of life left. Only when the surrounding shingles are also shot does a larger job make sense.
What is the most common place for flashing to leak?
The chimney, by a wide margin. It interrupts the roof plane on all four sides and relies on step flashing, counter-flashing, and a mortar or caulk seal, all of which move with freeze-thaw and dry out over time. Roof valleys and skylights are close behind. These transition points, not the open shingle field, cause the large majority of roof leaks, which is why any leak hunt should start at the nearest flashed joint uphill of the stain.
How often should roof flashing be inspected?
At least once a year, and again after any major wind or hail storm. Fall is ideal, since you can pair it with clearing the gutters and catch problems before winter freeze-thaw pries at loose metal. You are looking for rust, lifted or curled edges, and cracked sealant. Resealing joints every 5–10 years and fixing small issues on sight keeps flashing doing its job for the full 20–50 year life of the metal instead of failing early.