Chimney Flashing Repair Cost Guide
Chimney flashing repair costs $300–$800 for re-sealing and minor repairs, while complete chimney flashing replacement runs $800–$2,500 depending on chimney size and flashing material. Step flashing replacement costs $10–$20 per linear foot, counter flashing runs $15–$30 per linear foot, and cricket installation adds $500–$1,500. Lead and copper flashing materials cost 2–3 times more than galvanized steel but last significantly longer.
Chimney flashing is one of the most common leak sources on residential roofs, making it a steady repair revenue stream for roofing contractors. Proper chimney flashing involves multiple components — step flashing, counter flashing, base flashing, and often a cricket — and failure at any point creates water entry. Understanding chimney flashing systems and pricing the repair or replacement accurately ensures profitable work and eliminates expensive callbacks.
Step Flashing Repair and Replacement Costs
Step flashing is the interlocking L-shaped flashing woven into each shingle course along the chimney sides. Pre-bent step flashing pieces cost $1–$3 each for galvanized steel or $3–$6 each for aluminum. A typical chimney requires 15–30 step flashing pieces per side. Replacing step flashing requires removing the surrounding shingles, which adds labor — budget $10–$20 per linear foot installed for complete step flashing replacement including shingle removal and re-installation. For repair of a few displaced or corroded step flashing pieces, charge $200–$500 per side. Common step flashing failures include: corrosion of galvanized steel (especially in coastal or acidic environments), pieces that have shifted or pulled out due to thermal movement, and improper original installation where step flashings were not woven into each shingle course. Always replace step flashing during a re-roof — reusing old step flashing is a false economy that invites callbacks.
Counter Flashing Installation and Repair
Counter flashing covers the upper edge of the step flashing, preventing water from running behind it. The counter flashing is typically embedded in the chimney mortar joints (reglet-mounted) or surface-mounted with sealant. Reglet counter flashing is the preferred method: cut a slot in the mortar joint using a grinder with a diamond blade, insert the flashing, and seal with high-quality urethane caulk. Aluminum counter flashing costs $3–$5 per linear foot for materials, while lead-coated copper runs $8–$15 per linear foot. Installation runs $15–$30 per linear foot for reglet-mounted counter flashing. Surface-mounted counter flashing (attached to the chimney face with sealant) costs less at $10–$20 per linear foot installed but is less durable and less professional. For repair of existing counter flashing, re-sealing the reglet joint with fresh urethane sealant costs $200–$400 — this is a quick, high-margin repair when the flashing itself is still in good condition.
Chimney Cricket Installation Costs
A chimney cricket (also called a saddle) is a small peaked structure behind the chimney that diverts water and debris around the chimney. Building codes require a cricket when the chimney width exceeds 30 inches measured perpendicular to the slope. Cricket construction involves framing a small triangular structure on the roof deck (2x4 or 2x6 lumber), sheathing it with plywood, and covering it with metal flashing or membrane. Material costs run $100–$300, while labor for framing, sheathing, and flashing installation runs $400–$1,200 — total installed cost of $500–$1,500 depending on chimney width and roof pitch. Pre-fabricated metal crickets are available from companies like Chimney King for $100–$300, reducing installation time significantly. Always install a cricket during re-roofing if the chimney exceeds the 30-inch threshold — it is a code requirement and a major leak prevention feature. Photograph the completed cricket installation for your records.
Base Flashing and Front Apron Costs
The front apron flashing at the base of the chimney (where the lower roof slope meets the chimney face) is a critical waterproofing component. Fabricate apron flashing from a single piece of metal that extends at least 4 inches up the chimney face and 4 inches across the roof surface, tucked under the shingles. Galvanized steel apron flashing costs $20–$50 for materials; copper or lead-coated copper runs $50–$150. Installation runs $150–$400 for the apron alone. Apply ice and water shield membrane under the apron flashing and extending at least 12 inches up the roof deck behind the chimney. For complete base flashing systems (apron plus membrane), budget $250–$600. Common apron flashing failures include: inadequate overlap with step flashing at the corners (a frequent leak point), corrosion holes in older galvanized steel, and sealant failure at the chimney face. A well-fabricated apron with proper corner details eliminates the most common chimney leak location.
Flashing Material Selection and Pricing
Flashing material choice affects both cost and longevity. Galvanized steel is the economy option at $1–$3 per square foot — it costs less but corrodes in 15–25 years, especially in coastal, industrial, or high-humidity environments. Aluminum costs $2–$5 per square foot and resists corrosion better but can be damaged by alkaline mortar contact — use a barrier between aluminum and masonry. Lead flashing ($5–$10 per square foot) is extremely durable and malleable, conforming perfectly to irregular chimney surfaces, but environmental concerns limit its use in some areas. Copper ($8–$20 per square foot) is the premium choice — it lasts 70–100 years and develops an attractive patina. Lead-coated copper ($10–$25 per square foot) combines copper durability with lead solderability. For most residential work, recommend aluminum or lead-coated copper based on the homeowner budget. Always match the flashing material to the existing roof metals to prevent galvanic corrosion between dissimilar metals.
Pricing Chimney Flashing Work
Chimney flashing work should be priced as a specialty service. Set a minimum service call of $350–$500 for any chimney flashing repair — even simple re-sealing jobs require mobilization, ladder setup, and careful work at a critical detail. For complete chimney re-flashing (step flashing, counter flashing, apron, and cricket if needed), price the job at $800–$2,500 depending on chimney size, material choice, and accessibility. Always inspect the chimney masonry condition while you are there — cracked mortar, spalling brick, and deteriorated chimney caps are common, and recommending masonry repair (or referring to a mason) adds value. During roof replacements, present chimney re-flashing as an essential component, not an optional add-on. Price it as a separate line item at $500–$1,500 per chimney. On a re-roof, chimney re-flashing labor is more efficient because the surrounding shingles are already removed, so your margins are higher than standalone repairs.
Frequently Asked Questions
Signs that flashing needs attention include: visible rust or corrosion, gaps between flashing and chimney face, cracked or missing sealant in the reglet joint, water stains on interior ceilings or walls near the chimney, and lifted or displaced step flashing visible from the roof. If the flashing is more than 20 years old and showing any of these signs, recommend full replacement rather than patching.
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