Chimney Flashing Repair in Los Angeles
Leaking flashing can usually be resealed, re-seated or replaced — ideally before water reaches the wall framing behind it.
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About Chimney Flashing Repair
Chimney flashing is the metal seal between the chimney and the surrounding roof. It's a frequent source of water staining near chimneys — not because it's poorly designed, but because the chimney and the roof move independently through temperature changes, and the flexible sealant that bridges them eventually cracks and separates.
The tricky part about flashing failures is that water enters at the roofline but travels inside the wall cavity before appearing as a stain on the ceiling or wall. The stain rarely appears directly above the entry point. A homeowner who sees a water stain two feet from the chimney and patches the ceiling hasn't fixed anything — the water is still getting in at the roof.
Los Angeles' winter rain season — particularly the concentrated storm bursts that arrive off the Pacific and run up against the foothills — concentrates significant water exposure on chimney-to-roof intersections. Flashing that has been functioning adequately for years can develop a slow leak after one heavy storm season.
The Three Types of Chimney Flashing
Step Flashing
Individual L-shaped metal pieces installed in a staircase pattern along each side of the chimney, woven between the roof shingles. Each piece overlaps the one below it to direct water down and away.
Counter Flashing
Metal pieces embedded into the chimney mortar joints that overlap the top edge of the step flashing. This creates the watertight seal at the chimney face. When the mortar joint deteriorates, the counter flashing lifts and allows water behind it.
Saddle Flashing (Cricket)
A peaked ridge structure behind a wide chimney that diverts water around the chimney rather than letting it pool against the back. Building codes call for one behind chimneys above a certain width, and on older homes it is sometimes missing altogether.
Signs Your Chimney Flashing Needs Repair
Water stains on ceiling or wall near the chimney
The most common presenting symptom. Water enters at the roofline but travels inside the wall cavity before becoming visible — the stain is rarely directly over the entry point.
Rust or visible gaps in the flashing metal
Oxidized flashing metal has reached the end of its service life. Gaps between the flashing and the chimney masonry are a direct entry point.
Cracked, dried, or missing sealant at flashing joints
The flexible sealant that bridges the metal to the masonry shrinks and cracks over years of thermal cycling. The temperature swing between the Los Angeles coast and the inland valleys accelerates this.
Loose or lifted counter flashing
Counter flashing embedded in mortar joints lifts when the surrounding mortar deteriorates. A lifted edge creates a gap behind the metal on every rainfall.
Water in the firebox that isn't from the crown or cap
After confirming the cap and crown are intact, back-of-chimney flashing failure is the next thing to check — particularly the saddle flashing behind the chimney.
Musty smell near the chimney interior wall
Sustained moisture in the wall cavity from a slow flashing leak promotes mold growth before visible water staining appears.
Why Flashing Is Awkward to Repair Well
- Counter flashing re-embedding requires cutting and re-pointing masonry mortar joints — not just surface sealant
- Incorrect flashing slope or lapping can redirect water rather than stop it
- Saddle flashing installation behind wide chimneys requires framing and roofing coordination
- Roof access at chimney height requires fall protection equipment that most homeowners don't have
- Identifying the actual entry point requires experience — surface caulk over the wrong location does nothing
- The failing zone is often a small part of an otherwise sound flashing run, so what gets replaced is worth establishing before anything is removed
How Flashing Repair Works
Look at the flashing
The flashing run is assessed from the roof — step flashing condition, how the counter flashing is seated, the sealant joints, and how water drains behind the chimney.
Narrow down the entry point
Where it is not obvious which part of the run is failing, that gets established before anything is removed. Replacing intact material fixes nothing and hides what was actually leaking.
Remove deteriorated sealant
All cracked or failed sealant is removed completely before new material is applied — sealant over sealant doesn't hold.
Re-seat or replace flashing metal
Lifted counter flashing is re-embedded into fresh mortar. Corroded or damaged metal is replaced. Step flashing that has lifted from the shingles is reseated and secured.
Apply elastomeric sealant
Flexible elastomeric flashing compound is applied to the metal-to-masonry joints. It is used because it moves with thermal expansion rather than cracking away from it, which rigid compounds tend to do at this junction.
Check the work over
The finished joint is looked over, and anything noticed on the surrounding masonry or roof line while up there should be raised with you before anyone leaves.
What Drives the Cost
No price is published here: a fresh bead of sealant and new flashing with a cricket behind the chimney are not the same job. These are the variables that move it.
The roof covering
On asphalt shingle, step flashing can be worked out and back in with a few shingles lifted. Clay or concrete tile has to be lifted carefully and breaks easily. A flat roof uses a different detail altogether, with the roofing membrane turned up the chimney face beneath the counter flashing.
Resealing or replacing
Cutting out failed sealant and resealing sound metal is the smallest version of this job. Replacing corroded step flashing, or installing new flashing where the original detail was never right, is a different scale of work.
How the counter flashing is set
Properly set counter flashing sits in a reglet, a slot cut into a mortar joint. Replacing it means cutting or cleaning out that slot and repointing around the new metal. Counter flashing that was only surface-mounted relies entirely on its sealant.
Whether a cricket is needed
A wide chimney with no cricket (saddle) behind it may need one framed, sheathed and flashed. That is carpentry and roofing as much as flashing work.
Roof access and pitch
A steep roof, a tall eave or a chimney far from any safe ladder point takes more setup before any flashing is touched.
Whether roofing has to come up
If the roofing around the chimney has to be taken up and relaid, part of the job may belong to a roofer, and the two trades need to agree who handles which layer.
Call or send the details, and ask for an estimate for the work.
Where the Chimney System Ends
Water appearing near a chimney can come from the chimney flashing, from another part of the chimney — the crown, the cap, or the masonry itself — or from roofing outside the chimney system altogether. The roof covering, a valley, a vent or the decking can all fail close to a chimney and produce the same stain on the same ceiling.
If the evidence points to roofing outside the chimney system, a roofer is the appropriate specialist. This page covers chimneys and the flashing detail that seals them to the roof, not the rest of the roof. Flashing work that does not address the actual entry point changes nothing, and it is better to hear that before paying for it.
Where you know water is getting in but not from where, chimney leak repair works through the possible paths in turn rather than assuming the flashing. And where the masonry around the flashing has deteriorated — open joints, spalled brick, a stack that has moved — the counter flashing has nothing sound to be re-seated into, which makes it a masonry repair question before it is a flashing one.
Related Guides
Related chimney & fireplace services
Part of Leaks & Water Damage — Water is the single most common cause of chimney damage in Los Angeles. These pages cover where it gets in and what stops it.
- getting a leaking chimney repairedChimney Leak Repair — The repair page for water coming in — crown, flashing, cap, masonry or liner.
- the concrete slab at the top of the stackChimney Crown Repair — The slab that sheds rain off the top of the chimney, and what happens when it cracks.
- chimney waterproofingChimney Waterproofing — Vapour-permeable repellent on sound masonry. Prevention, not a leak fix.
- repairing damaged brick and mortarChimney Masonry Repair — Brick replacement, spalling, cracked faces and structural masonry damage.
Further reading: Why Chimney Flashing Leaks Happen and How to Spot Them · Chimney Leaks: Where the Water Usually Comes From
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The same work, explained for local conditions.
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When to call someone else
If you're not sure whether the leak is coming from the flashing, the crown, or the cap, start with a chimney inspection. Diagnosing the correct entry point before any repair prevents replacing components that aren't failing.
Have a question?
info@chimneycleaningla.comChimney Flashing Repair FAQ
More chimney and fireplace questions are answered on the main FAQ page.
Water showing up where the chimney meets the roof?
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