What Is Chimney Flashing and Why Does It Fail?
Chimney flashing is the metal seal where your chimney meets the roof. It has two parts: step flashing (L-shaped metal woven into the shingles) and counter flashing (embedded in the chimney mortar that overlaps the step flashing).
Flashing fails for several reasons in Chicago:
Freeze-thaw cycles expand and contract the metal, breaking sealant bonds Age — sealant and caulking deteriorate over 10–15 years Poor original installation (this is extremely common) Wind damage loosening connections Corrosion of galvanized steel flashing
How to Tell If Your Flashing Is Leaking
Water stains on the ceiling or walls near the chimney Damp spots in the attic near the chimney chase Peeling paint or wallpaper near the chimney Musty smell near the fireplace area Visible gaps between flashing and chimney or roof Rust stains running down the chimney
Flashing leaks often worsen during heavy rain or when snow melts on the roof. If you notice leaks only during certain weather, flashing is the prime suspect.
Flashing Repair Options and Costs
Recaulking/resealing (if flashing is intact): $200–$500 Partial flashing repair (replacing damaged sections): $400–$800 Full flashing replacement (step + counter flashing): $800–$1,500 Premium copper flashing installation: $1,200–$2,000+
Recaulking is a temporary fix that buys 2–5 years. If your flashing is original and the house is 15+ years old, full replacement with modern materials is the better investment.
Should a Roofer or Chimney Company Fix Flashing?
A chimney company is typically the better choice. Flashing connects two systems — your roof and your chimney — and chimney professionals understand both the masonry and waterproofing aspects.
Roofers tend to address only the roof side of the equation. A chimney professional will ensure the counter flashing is properly embedded in the mortar joints and that both roof and chimney sides are watertight.
Need Professional Help?
Widen Chicago provides honest diagnostics, transparent pricing, and expert service for every chimney and vent job. Same-week scheduling available.