Chimney Flashing Repair Cost

Chimney flashing repair cost depends on three things: the type of flashing failure, the roof material it's installed in, and how easily a crew can get to it safely. Pacific Northwest rain makes flashing one of the most common chimney repair needs in the region — and one of the most variable in pricing because of how many configurations exist.

What is chimney flashing and why does it fail?

Chimney flashing is the metal seal between the chimney and the roof. It's what keeps water from running down between the chimney and the roof deck. Two pieces work together: step flashing (woven into the roof courses up the side of the chimney) and counter flashing (embedded into the chimney mortar joints and overlapping the step flashing).

Flashing fails when the metal corrodes, when the sealant between counter flashing and the chimney mortar deteriorates, or when the original installation was wrong from day one. In the PNW, year-round rain accelerates all three failure modes. Chimney flashing repair is one of the most common service calls we get in our service area.

Cost factors specific to flashing repair

Beyond the general chimney repair factors that apply to any chimney work (see our chimney repair cost guide), flashing repair has several variables that move pricing meaningfully.

• Roof material. Composition shingle roofs are the easiest to work with. Cedar shake takes more care to lift and replace courses. Tile and slate roofs are the most complex — both for access and for re-integrating shingles around the new flashing.
• Type of flashing failure. Resealing existing flashing (caulking the counter flashing where it meets the chimney) is the simplest fix. Replacing corroded step flashing requires lifting roof courses. Full flashing replacement is most involved.
• Material choice. Galvanized steel is the budget option but corrodes faster in our climate. Aluminum, copper, and lead-coated copper last longer but cost more.
• Roof slope and access. A walkable 4/12 pitch is easy. A steep 12/12 pitch needs harness setup and slower work.
• Chimney shape. Square chimneys have four straightforward flashing pieces. Chimneys with offsets, multiple shoulders, or unusual geometry need custom-bent flashing.
• Underlying damage. If the flashing has been leaking for a while, the roof deck or chimney mortar underneath may need repair too. Often discovered once the old flashing is lifted off.

Three levels of flashing work

Flashing repair generally falls into three scopes, each with different cost profiles.

Why flashing is a frequent PNW problem

A few PNW-specific factors make chimney flashing fail more often here than in drier climates.

• Year-round rain volume. Flashing in dry climates can have minor imperfections that never cause issues. In our climate, even small failures result in active leaks within months.
• Original installation quality. A lot of older homes in our area were built before flashing standards were rigorous. Improperly installed flashing fails earlier and is often the actual root cause of "old" chimney leaks.
• Roof material mix. Cedar shake and composition shingle dominate the PNW housing stock. Cedar in particular is harder to integrate flashing into and tends to develop leaks over time.
• Moss and debris. Pacific Northwest roofs collect moss and organic debris that traps moisture against the flashing, accelerating corrosion.

When to repair vs. when to replace

The decision usually comes down to age, current condition, and roof material. Some quick heuristics:

• Flashing under 15 years old, intact, just leaking: usually reseal works.
• Flashing 15-30 years old, counter flashing showing wear: counter flashing replacement.
• Flashing 30+ years old, visible corrosion: full replacement is usually the right call. Resealing old failing flashing is a temporary fix that often needs to be redone within a year or two.
• Multiple flashing failures over the years: full replacement, possibly with an upgrade to copper or lead-coated copper for longevity.

Frequently asked questions