Chimney4uSeattle & Puget Sound

Chimney Flashing Repair

Stop the leak where your chimney meets the roof

A brown ring on the ceiling near the chimney, or damp sheathing in the attic around the chase, points first at the flashing — one of the easiest details on a roof to get wrong.

Flashing is a layered metal assembly, not a seam of caulk. Below: how step and counter flashing work together, how a flashing failure is told apart from a crown or masonry failure, and what a repair that holds involves.

Reviewed by Chimney4u editorial team · Last updated

What chimney flashing actually is

Flashing seals the joint where the chimney passes through the roof. It is not one piece, and it is not a strip of anything glued across a gap. On a sloped roof it is a layered assembly, and the layers have separate jobs.

Base flashing, and step flashing
The lower layer: metal that sits on the roof deck under the roofing and turns up against the chimney. Brick Industry Association detailing calls for at least 4 inches along the roof and 4 inches up the chimney face. On a slope it has to be stepped — L-shaped pieces woven in course by course, each lapping the one below, because a straight strip cannot follow a pitch.
Counter flashing
The upper layer, anchored in the chimney rather than the roof and lapped down over the top of the step flashing, so the vulnerable top edge of the lower layer is never exposed. It catches water running down the face of the masonry and sheds it onto the outside of the step flashing.
Through-wall flashing
Flashing carried all the way through the masonry to the outer face, where it turns down and forms a drip, sending water that is already inside the brick back out. In some details the counter flashing and the through-wall flashing are one piece.

Neither layer works alone: step flashing handles water coming down the roof, counter flashing handles water coming down the chimney and shields the step flashing's exposed top edge. The Brick Industry Association also notes the roof intersection is only one of three flashing zones on a chimney — the base and the area just under the crown are the others.

Why caulk and roof cement do not hold

Flashing is an expansion joint. The roof and the masonry expand and contract at different rates, and the flashing detail is what lets them move independently while still keeping water out. A rigid bead of sealant or a smear of roof cement across that joint is being asked to do the one thing the detail exists to avoid. Roof cement also hides the condition of the metal beneath it, and has to be stripped back to sound material before anything new can be set.

Telling a flashing leak from a crown or masonry leak

A stain near the chimney does not by itself mean the flashing failed. Water enters a chimney at several distinct points and each has a different repair. New flashing under a chimney that is really leaking through its crown does not stop the stain — you find that out one wet season later.

  • Points to the flashing. Staining close to where the chimney passes through the roof, worse in wind-driven rain than in still rain. Lifted, curled, or rust-streaked metal, roof cement over the joint, or daylight where metal meets brick.
  • Points to the crown. The crown is the sloped slab on top of the chimney. A cracked crown sends water straight down inside the masonry, so the signs show up high and inside — damp at the top, staining down the flue, moisture in the firebox — not at the roof line.
  • Points to the masonry itself. Efflorescence, spalled faces where the front of a brick has popped off, or open joints on the weather side. The Brick Industry Association states that heavy wind-driven rain will penetrate a single wythe of brickwork regardless of materials or workmanship.
  • Points to a missing or damaged cap. Water standing at the base of the flue, a rusting damper, or a musty smell after rain, with the roof-line joint dry.
  • Points somewhere other than the chimney. A stain nearer a plumbing vent, a valley, or a skylight. Water runs along rafters before it drops, so the wet ceiling is rarely under the hole.

Wide chimneys and the cricket on the upslope side

A wide chimney partway down a roof slope behaves like a dam: everything shedding off the roof above arrives at the uphill face and lingers there, with debris keeping the area damp between rains. A cricket is the fix, and it is a code requirement rather than an upgrade. The 2021 Washington State Residential Code requires one where the chimney dimension parallel to the ridgeline is greater than 30 inches and the chimney does not intersect the ridgeline, and requires the cricket-to-chimney intersection to be flashed and counter flashed the same way a normal roof-to-chimney intersection is. Required height is a fraction of the chimney's width and increases with roof slope.

Where flashing sits in the order of work

Flashing straddles two trades: the metal is anchored in masonry and woven into roofing. When the chimney needs more than one thing done, the order decides whether the work lasts or gets undone.

  1. Roofing decisions first

    If the roof is near the end of its life, do the flashing as part of the reroof rather than twice. Reroofing over old chimney flashing is the cheaper choice that produces the next leak.

  2. Masonry repairs next

    Counter flashing is let into a mortar joint, so repointing and crown work come first. A reglet cut into a soft or hollow joint gives the metal nothing to hold.

  3. Then the flashing itself

    Old metal, sealant, and roof cement come out, the reglet is cut, counter flashing is set and mortared, and stepped base flashing is woven back in with the roofing.

  4. Water repellent last, if at all

    The Brick Industry Association is explicit that a water repellent is not a substitute for real repairs and is not permanent. It goes on after the leak paths are closed, never instead.

  5. Interior repairs after the masonry dries

    Drywall, insulation, and framing are put right once water has stopped entering and the assembly has dried out.

The metal, and why it matters here

Metal choice matters most where flashing is embedded in masonry. The Brick Industry Association calls copper durable, tolerant of chimney temperatures, and safe to embed in fresh mortar, though it can stain the crown or brickwork. It calls stainless steel an excellent flashing material and specifies ASTM A240 Type 304 at a minimum thickness of 0.01 inch. It does not recommend galvanized steel, because thicker zinc coatings can crack where the metal is folded, and says aluminum should not be used in brick masonry because the alkalis in fresh mortar attack it.

What the job includes

  • An assessment from the roof and, where it can be reached, from inside the attic, to establish where water is actually entering
  • A written scope and price before any work begins, with nothing starting until you approve it
  • Removal of failed step and counter flashing, sealant, and accumulated roof cement over the joint
  • A reglet cut into a sound mortar joint, with new counter flashing let in, mortared solidly, and the joint tooled and sealed
  • New stepped base flashing woven in course by course as the roofing around the chimney is reset
  • Photographs of the chimney before and after, from the same angles where practical
  • A plain explanation of what was urgent, what can wait, and what does not need doing

What it does not include

  • Crown repair or replacement. A cracked crown, or one with no overhang, is chimney crown repair and is scoped separately.
  • Repointing, brick replacement, or rebuilding. Open joints and spalled brick are chimney masonry repair — a reglet cannot be cut into a joint with nothing left in it.
  • Reroofing, valley work, or roofing repairs away from the chimney. Only the roofing immediately around the chimney is lifted and reset.
  • Framing a new cricket where none exists. That is carpentry and roofing; it is identified during the assessment and quoted on its own, not folded silently into a flashing price.
  • Masonry waterproofing, which is a separate service and, per the Brick Industry Association, not a substitute for real repairs.
  • Interior repairs. Stained drywall, wet insulation, and rotted framing are put right by others once the leak is stopped and the area has dried.

How the work goes

  1. Assess from the attic and the roof

    Establish the entry point before anything is dismantled, checking the flashing against the crown, the masonry faces, the cap, and other roof penetrations nearby.

  2. Written scope and price

    You receive a written scope and price, including any masonry or roofing that has to happen first and in what order. Nothing starts until you approve it.

  3. Strip back to sound material

    Old flashing, sealant, and roof cement come off, and roofing immediately around the chimney is lifted so the deck and the base of the masonry can be seen.

  4. Set the counter flashing into the masonry

    Cut the reglet into a mortar joint, let the counter flashing in to the detailed depth, mortar it solidly, then tool and seal the joint.

  5. Weave and lap the stepped base flashing

    Step flashing goes in course by course with the roofing, each piece lapping the one below and running up the chimney face and out onto the roof, with the counter flashing lapping down over it.

  6. Seal, reinstate, and photograph

    Laps, bends, and corners are sealed, the roofing is closed back in, and before-and-after photographs are taken from the same angles where practical.

What to look for

A brown ring or spreading stain on the ceiling within a foot or two of the chimney
Water is entering at or near the roof line. Flashing is the first thing to rule in or out, though the stain can surface some distance from the entry point because water tracks along framing.
Rust streaks running down the metal or the brick at the roof-to-chimney joint
CSIA lists rust stains as one of the three water-intrusion signs a homeowner can see. Rust also says the metal is a corrodible type and is being wetted repeatedly.
Flashing that is lifted, bent, curled at the edge, or pulling away from the brick
CSIA names bent or damaged flashing as a water-intrusion sign. Once the top edge is open, water runs behind the metal instead of over it.
Cracked, crumbling, or repeatedly reapplied roof cement over the joint
The joint has been patched rather than rebuilt. A rigid material over a moving joint fails again, and each patch tends to buy a shorter interval than the last.
Damp insulation or dark staining on the attic sheathing around the chimney chase
Water has been entering long enough to wet the framing. The attic is usually where the path is easiest to see, and worth checking before opening the ceiling below.
A leak that started after a reroof and was not there before
Old chimney flashing is often reused or shingled over during a reroof rather than replaced. Worth raising with whoever did the roofing.

What changes the price

We do not publish a headline figure, because it would be a guess about your chimney. These are the things that genuinely move the number, and we put a real one in writing after we have looked.

Roof pitch and height
A steeper or higher roof takes longer to work on safely. Work reachable from a ladder is a different proposition from work needing fall protection and roof anchors.
Roofing material
Composition shingle lifts and resets more easily than tile, slate, cedar shake, or standing-seam metal. Some materials cannot be reused once disturbed; some are brittle enough that neighbouring pieces break during the work.
Chimney width and the number of faces at the roof line
A narrow chimney at a gable end has few joints. A wide one crossing the slope has an uphill face, two sides, and a downhill face, and each face adds step flashing, counter flashing, and corners.
Whether a cricket is present or required
Adding a cricket to a wide chimney that has none turns metalwork into framing, then roofing, then flashing — a materially larger scope than reflashing an existing detail.
Condition of the mortar joints
Counter flashing has to be let into a sound joint. Open, soft, or face-patched joints mean repointing first, which is separate work with its own sequence.
Metal specified
Copper and stainless steel behave differently from cheaper metals where flashing is embedded in mortar and exposed to a long wet season. The choice is made with you as part of the written scope.

Common questions

How do I know the leak is the flashing and not the chimney crown?
Position and timing. A flashing failure stains near the roof line and is usually worse in wind-driven rain; a cracked crown sends water down inside the masonry, so it shows up higher or inside the flue and firebox. Confirming it means looking from both sides — NFPA 211's Level II inspection covers what is reachable without demolition, including accessible attics, and CSIA's Level 2 procedure requires getting on the roof. Both can be failing at once, which is why the assessment comes before the quote.
Can I just caulk the flashing myself and be done with it?
It buys time and not much more. Flashing is an expansion joint between a roof and masonry that move at different rates, so a rigid bead across it has to crack. Sealant is part of a flashing assembly — the reglet joint is tooled and sealed, laps and bends are sealed — but the Brick Industry Association's position is that flashing which does not extend properly through the masonry and form a drip is of almost no benefit. If a caulk repair has already failed once, the metal underneath it is what needs attention.
Does chimney flashing repair need a permit in Seattle?
It depends on the scope and the chimney. Seattle generally requires a building permit before altering or repairing a structure, exempts minor repairs under a value threshold set in the code, and is clear that being exempt from a permit does not exempt the work from the building code. Unreinforced masonry chimneys have their own rule — SDCI Director's Rule 07-2025, effective January 8, 2026 — requiring a permit for unreinforced masonry chimney work with only narrow exceptions. Requirements change and depend on the property, so confirm with SDCI before work starts.
Should a roofer or a chimney company do this work?
Both trades touch the detail, and whoever does it has to be comfortable on both sides of the joint — cutting a reglet into masonry and weaving step flashing into roofing. What is legally enforceable in Washington is L&I contractor registration rather than any chimney certification, and you can look up a contractor's registration and its current status free at L&I before hiring. If the roof is near the end of its life, doing the flashing as part of the reroof usually beats doing it twice.
My chimney is wide and there is no cricket behind it. Is that a problem?
Probably, and it is worth settling before flashing is quoted. The 2021 Washington State Residential Code requires a cricket where the chimney dimension parallel to the ridgeline exceeds 30 inches and the chimney does not meet the ridgeline, with the cricket-to-chimney intersection flashed and counter flashed like any other. Code editions and local amendments change, so confirm the current requirement with your building department first.
The stain came back after the flashing was replaced. What now?
Usually a second water path was open all along. CSIA names four things that keep water out of a masonry chimney — a cap, a sound crown, sound flashing, and waterproofing — so new flashing under a cracked crown or an uncapped flue closes only one. The Brick Industry Association's guidance on recurring efflorescence is to find the moisture source before further repairs, and the National Park Service is equally direct that repointing fails again if the leak feeding it was never corrected. Look at the crown, the cap, and the masonry faces next.

Sources

  1. Technical Notes on Brick Construction 46 - Maintenance of Brick Masonry — Brick Industry Association, December 2017. Accessed 2026-08-27.
  2. FLASHING CHIMNEYS (Brick Brief, July 2005) — Brick Industry Association. Accessed 2026-08-27.
  3. Builder Notes Issue 4 - Brick Veneer Construction: Advanced Flashing - Roofs and Chimneys — Brick Industry Association. Accessed 2026-08-27.
  4. Technical Notes 19B - Residential Chimneys - Design and Construction — Brick Industry Association. Accessed 2026-08-27.
  5. Technical Note 7 - Water Penetration Resistance: Design and Detailing, November 2017 — Brick Industry Association. Accessed 2026-08-27.
  6. Standard Operating Procedure - Level 2 Inspection, Masonry Fireplace (Rev. 4/5/19) — Chimney Safety Institute of America (CSIA). Accessed 2026-08-27.
  7. Four Low-Cost Recommendations to Prevent Major Water Damage — Chimney Safety Institute of America (CSIA), dated June 11, 2010. Accessed 2026-08-27.
  8. Water, not fire, causes most chimney damage — Chimney Safety Institute of America (CSIA) press release, hosted on the NCSG association platform. Accessed 2026-08-27.
  9. Standard Operating Procedure - Level 1 Inspection, Masonry Chimney Attached to a Building Heating Appliance (Rev. 4/5/19) — Chimney Safety Institute of America (CSIA). Accessed 2026-08-27.
  10. Committee Input No. 9-NFPA 211-2024 [ Chapter 15 ] - First Draft Committee Input Statements, NFPA 211 A2026 cycle — National Fire Protection Association (NFPA). Accessed 2026-08-27.
  11. U.S. Annual/Seasonal Climate Normals 1991-2020, station USW00024233 (precipitation-day counts) — NOAA National Centers for Environmental Information (NCEI). Accessed 2026-08-27.
  12. U.S. Annual/Seasonal Climate Normals 1991-2020, station USW00024233 (seasonal precipitation) — NOAA National Centers for Environmental Information (NCEI). Accessed 2026-08-27.
  13. Preservation Briefs 2: Repointing Mortar Joints in Historic Masonry Buildings — U.S. National Park Service, Heritage Preservation Services (Robert C. Mack, FAIA and John P. Speweik), October 1998, ISSN 0885-7016. Accessed 2026-08-27.
  14. Fixing Leaky Chimney Systems (Part 2 - Crowns) — SaverSystems (ChimneySaver), article by Stuart Karanovich, April 3, 2025. Accessed 2026-08-27.
  15. Fixing Leaky Chimney Systems (Part 3 - Flashing) — SaverSystems (ChimneySaver), article by Stuart Karanovich, April 3, 2025. Accessed 2026-08-27.
  16. 2021 Seattle Residential Code, Chapter 1 Scope and Administration — Seattle Department of Construction and Inspections (SDCI). Accessed 2026-08-27.
  17. SDCI Director's Rule 07-2025, Alteration and Repair of Unreinforced Masonry Chimneys — Seattle Department of Construction and Inspections (SDCI). Accessed 2026-08-27.
  18. R1003.20 Chimney Crickets (IRC 2021 text) — UpCodes (reproducing IRC 2021 model code text). Accessed 2026-08-27.
  19. Register as a Contractor — Washington State Department of Labor & Industries. Accessed 2026-08-27.
  20. Verify a Contractor, Tradesperson or Business — Washington State Department of Labor & Industries. Accessed 2026-08-27.

Next step

Start with an inspection

Tell us what you have noticed. We will look at the chimney, show you what we found, and put a price on the work before anything begins.

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