Chimney Flashing Cost Calculator

What this calculator estimates

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

• Chimney flashing assembly — apron + step + counter-flashing scaled by chimney size class.
• Cricket / saddle — required by IRC R1003.20 on chimneys wider than 30 inches.
• Tuck-pointing — mason labour to repair deteriorated mortar joints before counter-flashing can be reglet-cut.
• Crown / cap repair — when the chimney top has cracked or spalled.
• 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 small-chimney flashing replacement carries that floor because mobilizing a two-person crew, ladders, and basic materials is the dominant cost on small jobs.

How to use it

1. Count chimneys that need flashing replacement. Each gets its own assembly.
2. Pick chimney size — small (single flue, ~24 in), medium (~30 in default), large (~36x48 in), oversize (48x60+ in). Size scales the apron + step + counter perimeter.
3. Pick material. Aluminum is the 2026 US default. Copper for slate/tile/historic. Lead where it remains legal and specified. Zinc as the European-influenced premium. Galvanized is the low-end option.
4. Set storey count — labor multiplier is 1.0× single-storey, 1.2× two-storey, 1.45× three-storey or higher.
5. Pick masonry condition. Good = no tuck-pointing. Fair = 2 hours of mason labour. Poor = 6 hours of mason labour at local mason rates.
6. Toggle cricket / saddle if your chimney is wider than 30 inches measured across the roof slope.
7. Toggle cap / crown repair if the chimney top is spalled or cracked. Often discovered during the flashing job.
8. Toggle add-ons — permit, disposal, weekend premium, and any extra labour hours for carpentry repairs to rotted sheathing.

Typical 2026 US chimney 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.

Add 20% for two-storey access and 45% for three-storey or higher.

Cost drivers

Chimney size class. A single-flue 24-inch chimney has roughly 8 linear feet of flashing perimeter. A double-flue 36-inch chimney is 14 linear feet. An oversize 48x60-inch stack on a center-chimney colonial is 20+ feet plus a substantial cricket. The labor and material scale near-linearly with perimeter, which is why size class is the biggest cost lever.

Masonry condition. Counter-flashing has to seat into a reglet cut into the mortar joint. If the mortar is sound, this is 30 minutes per side with a grinder. If the mortar is crumbling, it has to be ground out, repacked with fresh Type N mortar, cured 24 hours, and only then reglet-cut. Deteriorated masonry adds $450–$650 to a typical job.

Material choice. Aluminum at ~$1.85/lb in 2026 dominates US residential. Copper at ~$5.20/lb is the slate/tile premium. Lead Code 4 at ~$1.40/lb raw is cheap but heavy and limited in some jurisdictions. Zinc at ~$3.40/lb is a European-influenced premium choice. Galvanized at ~$1.10/lb is the budget option, increasingly rare because of accelerated corrosion in modern atmospheres.

Building height. Two-storey chimney work requires 28–32 ft extension ladders with stand-off stabilizers and OSHA-compliant fall protection above 6 ft (29 CFR 1926.501). Three-storey work commonly needs scaffold rental ($150–$400/day) or a powered lift ($350–$750/day), and the labor multiplier accordingly jumps to 1.45×.

Cricket requirement. IRC R1003.20 mandates a cricket on chimneys wider than 30 inches measured perpendicular to the roof slope. A cricket is fabricated from sheathing, underlayment, ice-and-water shield, flashing, and matching roof covering — typically adding 4–6 hours of labour plus $80–$140 in materials. Skipping a required cricket is a code violation that will cause both leaks and a failed inspection if a permit is pulled.

Crown / cap condition. The chimney crown is the masonry cap on top of the brick that sheds water away from the flue. When the crown cracks, water enters the brick from above and migrates down to the flashing — replacing flashing without fixing the crown means re-leaking within 1–3 years. Discovery of a failed crown during a flashing job adds $280–$420 to the bill.

Carpentry repair. Failed chimney flashing usually means water has been entering the structure for months or years. Rotted sheathing under the flashing is common — every 10 sq ft of replacement adds $150–$280.

Per-locale code and standards (US)

• 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.
• IRC R1003.20 — Cricket required on the upslope side of chimneys wider than 30 inches measured perpendicular to the roof.
• IRC R1003.9 — Chimney crown construction 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 and minimum step-flashing dimensions.
• NFPA 211 — Chimney inspection and maintenance requirements.

A contractor proposing to reuse existing chimney flashing during a re-roof is voiding the shingle manufacturer warranty — GAF, Owens Corning, CertainTeed, and IKO all require new flashing at chimneys, skylights, sidewalls, and headwalls when re-roofing.

The four-piece chimney flashing assembly

Apron flashing. The piece that wraps across the downhill (front) face of the chimney, lapping over the shingles below. Typically 8–14 inches up the chimney and 6 inches over the shingle field.

Step flashing. L-shaped pieces (5x7 inches standard) interleaved one-per-shingle-course along each sidewall of the chimney, lapping at least 2 inches over the course below.

Counter-flashing. Installed into a reglet groove cut into a masonry mortar joint, then bent down and over the top edge of the step flashing to seal the joint between metal and brick. The fact that counter-flashing is not nailed to the brick — it’s wedged into the reglet and lead-caulked — is what allows it to expand and contract with temperature without tearing.

Cricket flashing. On the upslope (back) face of chimneys wider than 30 inches. A small saddle-shaped roof structure with its own apron at the bottom and side step flashings tied into the main roof. Required by IRC R1003.20.

Diagnostic step-by-step

1. Look for staining on interior walls or ceilings near the chimney — a tell-tale sign of failed chimney flashing.
2. Inspect attic decking at the four corners of the chimney after heavy rain — dark wet stains confirm a leak.
3. Probe the mortar joints at the chimney sides with a screwdriver — soft or crumbling mortar means the counter-flashing reglet has failed.
4. Walk the roof with binoculars — lifted or visibly rusted step flashing along a sidewall is the most common failure mode.
5. Inspect the crown from a ladder — visible cracks mean water is entering from above and the flashing alone won’t stop the leak.
6. Photograph everything before getting quotes — your photos are the baseline for comparing contractor recommendations.

Avoiding scams and overcharging

The chimney-flashing 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, itemized quote.
• Cash-only or wire-transfer demands.
• Refusal to provide license number or proof of insurance.
• Up-selling from a $500 chimney flashing repair to a $14,000 full re-roof at the first visit without a written diagnostic.

Insist on a written estimate that itemizes chimney size, material specification, masonry condition assessment, whether a cricket is included, and what’s specifically included in labour. Get insurance and license proof before any work begins.

Related calculators and guides

• Roof flashing cost calculator — when the scope extends to step, valley, drip edge, and headwall
• Roof leak repair cost calculator — when chimney flashing failure has caused interior damage
• Skylight installation cost calculator — paired with chimney for whole-roof penetration scope

Sources: 2026 HomeAdvisor Chimney Flashing Cost Guide; Angi 2026 True Cost Report; IRC 2024 R903.2, R905.2.8, R1003.9, R1003.20; ASTM A653, B370; NRCA Architectural Manual; NFPA 211; OSHA 29 CFR 1926.501.