Roof Flashing Cost Calculator

What this calculator estimates

This calculator quotes the all-in installed price for residential roof flashing replacement in 2026 US dollars. It separates the bill into the line items real roofers invoice:

• Chimney flashing — apron + step + counter-flashing kit installed at the chimney perimeter, including reglet cut and mortar repointing.
• Skylight flashing — manufacturer-spec flashing kit (Velux, Fakro, VELUX) installed around the curb.
• Step flashing — L-shaped pieces interleaved with shingle courses where the roof meets a vertical sidewall.
• Valley flashing — open or closed valley metal installed where two roof planes meet.
• Drip edge — perimeter flashing along eaves and rakes.
• Headwall / counter-flashing — at horizontal roof-to-wall transitions, with a counter-flashing piece embedded in or hooked over the wall cladding.
• Permit — typical municipal building permit fee when required.
• Disposal — debris haul-away and dump fee.
• Weekend / after-hours premium — 25% surcharge.

A minimum service-call floor of $325 applies in most US metro markets — even a single skylight flashing replacement carries that floor because mobilizing a 2-person crew, ladders, and basic materials is the dominant cost.

How to use it

1. Count chimneys and skylights that need flashing replacement. Each gets a manufacturer-spec kit.
2. Measure step flashing length — total linear feet of sidewall-to-roof intersections. A single dormer typically has 10–14 ft per side.
3. Measure valley flashing length — total linear feet of valleys. A simple gable roof has zero; a hip-and-valley colonial commonly has 30–60 ft.
4. Measure drip edge — total perimeter of eaves and rakes. A 40x25 ft ranch is ~130 ft.
5. Measure headwall — total linear feet where the roof terminates against a vertical wall (e.g., porch roof meeting house wall).
6. Pick material. Aluminum is the 2026 default. Copper for slate/tile/historic. Lead Code 4 only in regions where it remains legal and specified. Zinc is the European-influenced premium choice. Galvanized is the low-end option, increasingly rare in residential because of accelerated corrosion in modern atmospheres.
7. Set storey count. Labor multiplier is 1.0× for single-storey, 1.2× for two-storey, 1.45× for three-storey or higher.
8. Toggle add-ons. Permit, disposal, weekend premium, and any extra labour hours (carpentry, tuck-pointing) adjust the total.

Typical 2026 US roof flashing cost ranges

These ranges reflect 2026 nationwide pricing pulled from HomeAdvisor, Angi True Cost Report, NRCA contractor surveys, and Q1 2026 quotes from major US metros.

Copper roughly 3.4×, lead 2.1×, zinc 2.55×, galvanized 0.85× the aluminum base. Add 20% for two-storey and 45% for three-storey or higher.

Cost drivers

Material choice. Material is 35–55% of a flashing line item. Aluminum at ~$1.85/lb in 2026 is the cost-effective default. Copper at ~$5.20/lb and zinc at ~$3.40/lb scale aggressively when you total several hundred linear feet. Lead at ~$1.40/lb is cheap raw but heavy labour because of bending and soldering.

Building height. Two-storey eaves require 28–32 ft ladders, stand-off stabilizers, and OSHA-compliant fall protection above 6 ft (29 CFR 1926.501). Three-storey work often requires roof anchors, scaffold rental ($150–$400/day), or a powered lift.

Substrate complexity. A simple gable roof needs only drip edge and headwall flashing. A complex hip-and-valley roof with multiple dormers, a chimney, two skylights, and a porch roof can easily have 12 distinct flashing details — each its own setup and labor sequence.

Masonry condition. Old chimneys with deteriorated mortar require tuck-pointing before counter-flashing can be installed into a reglet. Add 1–4 hours of mason labour at $75–$125/hr.

Carpentry repair. Failed flashing usually means water has been entering the structure for months or years. Sheathing replacement, fascia repair, and rafter-tail sistering add $200–$1,500 depending on damage extent.

Geographic spread. California, the Pacific Northwest, and the Northeast are 15–25% above the national median. The Southeast is 10–15% below. Texas, the Midwest, and Mountain states are within 5% of the national median. Coastal markets (saltwater corrosion) often spec copper or stainless instead of aluminum, raising the bill 2–3×.

Per-locale code and standards (US)

US flashing installation is governed by:

• IRC R903.2 — Flashing required at wall-roof intersections, valleys, skylights, chimneys, and other roof penetrations.
• IRC R905.2.8 — Asphalt shingle flashing details, including step flashing requirements.
• ASTM A653 / A653M — Galvanized steel sheet specifications for steel flashings.
• ASTM B370 — Copper sheet and strip for building construction.
• NRCA Architectural Manual — Industry-standard detailing for residential flashing including 4-inch minimum vertical and horizontal flashing legs.
• Manufacturer requirements — GAF, Owens Corning, CertainTeed, IKO all require new flashing during re-roof to maintain warranty.

If a contractor proposes reusing existing step flashing during a re-roof, walk away — every major shingle manufacturer voids warranty in that scenario.

Flashing types and where each goes

Apron flashing — the front-face flashing across the downhill side of a chimney or skylight, lapped over the shingles below.

Step flashing — L-shaped pieces (typically 5x7 inches) interleaved one-per-shingle-course along sidewalls of chimneys, skylights, dormers, and house-to-porch transitions.

Counter-flashing — installed into a reglet cut into masonry (or under siding) and bent down over the step flashing to seal the top edge.

Cricket flashing — a small saddle-shaped roof structure on the upslope side of wide chimneys (over 30 inches) to divert water around the chimney instead of damming behind it. IRC R1003.20 requires crickets behind chimneys wider than 30 inches.

Valley flashing — open valleys show 4–6 inches of exposed metal; closed valleys have shingles woven or cut over the metal. Both require valley metal underneath, ideally 24 inches wide on a single-piece, no-splice run.

Drip edge — installed along eaves under the underlayment and along rakes over the underlayment. IRC R905.2.8.5 requires it in most jurisdictions.

Headwall flashing — the horizontal counterpart of step flashing, used where the roof terminates against a vertical wall.

Diagnostic step-by-step

1. Look for staining on interior walls or ceilings under or near roof penetrations — a tell-tale sign of failed chimney or skylight flashing.
2. Inspect attic decking from below after a heavy rain — dark wet stains under flashing locations confirm a leak.
3. Walk the roof edge with binoculars — lifted or visibly rusted step flashing along a sidewall is the most common failure mode.
4. Check the chimney crown — if the mortar is cracked, counter-flashing has likely lifted along with it.
5. Probe the fascia under suspect drip edge — soft fascia means chronic seepage.
6. Photograph everything before getting quotes — contractors will give different recommendations; your photos are the baseline for comparing.

Avoiding scams and overcharging

The flashing-only repair market is a common door-knocker scam target after wind storms. Red flags:

• “Storm damage” claims after a normal rain event.
• Pressure to sign before written quote.
• Cash-only or wire-transfer demands.
• Refusal to provide license number or proof of insurance.
• Up-selling from a $400 flashing repair to a $14,000 full re-roof at the first visit without a written diagnostic.

Insist on a written estimate that itemizes linear feet, component type, material specification, and what’s included in labour. Get insurance and license proof before any work begins.

Related calculators and guides

• Roof leak repair cost calculator — when flashing failure has caused interior damage
• Roof replacement cost calculator — when re-roofing is the better economic call
• Gutter installation cost calculator — drip edge integration with new gutters

Sources: 2026 HomeAdvisor Roof Flashing Cost Guide; Angi 2026 True Cost Report; IRC 2024 R903.2, R905.2.8, R1003.20; ASTM A653, B370; NRCA Architectural Manual; OSHA 29 CFR 1926.501.