Chimney Flashing Explained: Step, Counter and Cricket

Every chimney rises through the roof plane at a hard right angle, and that intersection is one of the most demanding water-management details on the entire house. Wherever a vertical surface meets a sloped one, the roof has to be built out of shingles and underlayment while the wall has to be built out of brick, block, or stucco, and neither material seals against the other on its own. The seal comes from a system of metal, flashing, layered and shaped to carry water down and away from every seam. When people say a chimney leaks, what they almost always mean is that the flashing around it has failed. The masonry itself is rarely the problem. Understanding the three parts of a proper chimney flashing system, step flashing, counterflashing, and the cricket on wider chimneys, is the fastest way to tell a real repair from a smear of tar that will fail again next season.

01 / THE SHORT ANSWERA watertight chimney is three details, not one

A properly flashed chimney is built from three distinct pieces working together, each solving a different part of the same problem. Step flashing handles the water running down the roof slope on either side of the chimney. Counterflashing, set into the masonry above it, covers the top edge of the step flashing so water can never get behind it. And on a chimney wide enough to dam water and snow on its uphill side, a cricket, sometimes called a saddle, splits that flow around the corners instead of letting it pool against the brick. Skip any one of the three, or install it wrong, and the chimney leaks. Get all three right, and the same chimney can go decades without a drop finding its way inside.

This matters for anyone comparing repair quotes, because the three-part system is also the three-part checklist. A contractor who talks about resealing a chimney without mentioning step flashing, counterflashing, or the cricket where one is needed is very likely planning to caulk over the symptom rather than rebuild the detail that actually keeps water out.

02 / THE FIRST LAYERStep flashing, piece by piece

Step flashing is a run of small, L-shaped metal pieces, one installed with every course of shingles that climbs alongside the chimney. Each piece is bent so one leg lies flat under the shingle course and the other leg turns up against the chimney's masonry. The next shingle course goes down over the bottom of that piece, and the next step flashing piece goes in above it, overlapping the one below by a few inches. Layer after layer, each piece sheds water onto the piece beneath it and out onto the shingle field, the same way roof shingles themselves overlap to shed water downhill.

Done correctly, step flashing is never a single continuous strip of metal bent to fit the roof pitch. A single bent piece cannot flex with roof movement or thermal expansion over a Macomb County temperature swing that runs from summer heat to well below freezing, and it tends to crack or pull loose at the bend over time. Individual step pieces, one per course, move independently and last far longer. If you can see a chimney's flashing from a ladder or a neighboring roofline and it looks like one long strip of bent metal rather than a stack of individual step pieces, that is worth flagging to whoever inspects the roof next.

03 / THE SECOND LAYERCounterflashing: the piece cut into the mortar

Step flashing alone is not enough, because its top edge is exposed against the brick, and wind-driven rain can get behind that edge if nothing covers it. Counterflashing is the second piece of metal that solves this: it is cut into the mortar joints of the chimney itself, usually in a reglet, a small groove ground or raked into the mortar, then bent to overlap down over the top of the step flashing like a cap. Water running down the brick face hits the counterflashing first and is thrown clear of the step flashing underneath, never given the chance to work behind it.

The distinction matters because it defines where each piece is fastened. Step flashing is part of the roof system, integrated with the shingles. Counterflashing is part of the masonry system, set into the chimney itself and sealed with mortar or masonry sealant at the reglet, not caulked to the roof surface. A chimney where the top piece of metal is simply caulked to the face of the brick, rather than physically cut into a mortar joint, is missing this layer, and that seam is one thermal cycle away from separating.

04 / THE THIRD PIECEThe cricket, for wide chimneys

Step and counterflashing manage water running along the sides of a chimney. They do not solve the problem on the uphill, high side, where the roof slope runs directly into the back of the masonry and has nowhere to go. On a narrow chimney this is a small volume of water and snow, easy to manage. On a wide chimney it can be a real load, water and Michigan snowmelt ponding against the brick every time it rains or thaws, exactly where the masonry meets the roof deck.

A cricket is a small secondary roof structure, built behind the chimney, that peaks in the middle and slopes down to each side. Instead of water hitting a wall and pooling, it hits the cricket's peak and is diverted around both corners of the chimney onto the main roof, where it can run off normally. Building codes require a cricket once a chimney reaches a certain width measured along the roof's high side, and the exact threshold is worth confirming for your specific chimney rather than assuming. Our companion guide on what a chimney cricket is and whether you need one covers that threshold, the leak signature of a missing cricket, and what it looks like to add one at reroof time.

A missing cricket does not usually show up as a puddle on the roof. It shows up as a stain creeping down the ceiling on the chimney's uphill side, months after the water started finding a way in.

05 / THE SHORTCUT THAT FAILSWhy tar and caulk always fail here

The fastest, cheapest response to a chimney leak is a bucket of roofing tar or a tube of caulk smeared along the seam where the flashing meets the brick. It stops the drip for a season, sometimes two, and that is exactly why it keeps getting used. It is also why it keeps failing. Tar and caulk are surface coatings. They do not address the fact that water is finding a path behind the flashing, they just block that path from the outside, on top of materials that are already moving independently: brick and mortar expand and contract at a different rate than metal flashing and asphalt shingles, and Macomb County's freeze and thaw cycles put that mismatch through its paces dozens of times a winter.

A surface sealant bridges that movement rigidly for a while, then cracks at the exact seam it was meant to protect, usually within a year or two. Because the crack forms in the same spot every time, homeowners often end up recaulking the same corner repeatedly, sometimes for years, without ever fixing the underlying flashing detail. Each recoating also makes the eventual proper repair a little more expensive, because a roofer has to strip years of hardened, brittle tar off the flashing and masonry before rebuilding the joint correctly.

There is one legitimate, limited use for sealant in a chimney flashing system: as a secondary seal at the reglet where counterflashing is set into mortar, applied over correctly lapped metal, not as a replacement for it. The difference is whether the sealant is backing up metal that is already doing the shedding, or trying to do the shedding itself. The first is normal, permanent flashing work. The second is a patch with an expiration date.

06 / JUDGING A QUOTEWhat a proper repair sequence looks like

When chimney flashing has failed, whether from age, a prior sloppy patch, or storm damage, a correct repair follows a sequence, and knowing it is the easiest way to tell a real fix from a shortcut when you are comparing quotes.

1. The old flashing and any sealant buildup come off. Old step flashing, counterflashing, and years of hardened tar or caulk are removed down to the shingles and the brick, so the crew can see the actual condition of both.
2. The deck and shingles around the chimney are checked. Water that has been getting behind failed flashing for a while often means the shingles and the decking closest to the chimney need attention too, not just the metal.
3. New step flashing goes in with the shingle courses. Individual pieces, one per course, correctly lapped, not a single bent strip pretending to do the same job.
4. A new reglet is cut, or the existing one cleaned out, and new counterflashing is set into the mortar joint and bent down over the step flashing, restoring the layer that throws water clear before it can get behind anything.
5. A cricket is built or repaired if the chimney is wide enough to need one, diverting water and snowmelt around the corners instead of letting it pond against the uphill side.
6. Sealant is applied only at the reglet, as a secondary seal over correctly lapped metal, never as the primary defense along an exposed seam.

If a quote skips straight to step six, and the whole plan is caulk or a flashing sealant coating applied over what is already there, you are being sold a patch, not a repair. A written quote for chimney flashing work should describe at least steps one through four in some form, because those are the steps that actually stop the leak rather than delaying it.

Storm events add one more wrinkle worth knowing. Wind can lift or tear flashing that was otherwise sound, and Macomb County has recent history here: the county was included in federal disaster declaration DR-4757 after the severe wind storms of August 2023. Damage of that kind may be covered by a homeowners policy, since coverage generally responds to sudden events rather than gradual wear, though every policy reads differently and no contractor can promise how a claim will be decided. Our storm and insurance claims guide walks through documentation and what we can and cannot do to help.

07 / THE COSTCost, timing and getting it fixed

Chimney flashing work is priced as a repair in our published canon, and Macomb County roof repairs generally run $350 to $3,200 depending on scope. A single-story chimney with sound step flashing that just needs new counterflashing set into the mortar lands toward the lower end. A wide chimney needing a full flashing rebuild plus a new cricket, or one where years of tar have to be stripped and the decking beneath repaired, runs higher, and larger or more complex jobs can exceed that range.

Chimney flashing also comes up naturally during a full roof replacement, since every flashing detail on the roof gets reset as part of that job anyway, and our replacement cost guide walks through when a full reroof makes more sense than another round of flashing repairs. Short of that, our repair estimator and cost calculator use the same published ranges as our honest pricing sheet, and a chimney flashing job is scoped the same honest way: photos of the current flashing, a written price, and no obligation to move forward.

Timing matters more here than it does for a lot of repairs, because a chimney leak rarely stays a chimney-sized problem. Water that gets behind failed flashing follows the rafters and the decking, and it can show up on a ceiling well away from the chimney itself, long after the leak started. A stain that appears near a chimney after a heavy rain or a fast thaw is worth an inspection before another season of freeze and thaw makes the repair bigger than it needs to be. Related small parts fail the same way for similar reasons: our guides on plumbing vent boot leaks and kickout flashing cover the other small metal details that quietly cause big leaks when they are missing or worn out, and the full library lives in our guides section.