The Short Answer
A chimney leak comes from the top or the sides of the masonry: a cracked crown, a missing cap, or brick and mortar soaking up rain. A roof leak at the chimney comes from the flashing where the roof meets the brick, or from water piling up behind a chimney with no cricket. Water in the firebox or wet brick high in the attic points to the masonry. Wet decking and rafters beside the chimney point to the flashing.
Key Points
- Water inside the flue or firebox almost always enters from the top of the chimney, not from the roof flashing.
- Wet brick inside the attic above the roof line means water is coming through the masonry itself.
- Wet decking or rafters at the base of the chimney, worst on the uphill side, points to flashing or a missing cricket.
- Roofers fix flashing and crickets; crowns, repointing and spalled brick belong to a mason or chimney professional.
- Fix the masonry before the flashing, because new counter flashing is set into mortar joints that a mason may need to redo.
A Chimney Is a Hole in the Roof With Its Own Weather Problems
Most of a roof is simple: shingles overlap, water runs downhill and off. A chimney interrupts that on all four sides, and then it keeps going up into the weather as a separate structure. Rain hits its top, soaks its sides and runs down its faces onto the roof. Every one of those surfaces can let water in.
That is why the question is not really chimney or roof. It is which part of the chimney assembly failed. The top and the sides are masonry. The joint where the brick meets the shingles is roofing. The uphill side, where snow and water collect, can be either, depending on whether the chimney has a cricket.
The Six Places a Chimney Lets Water In
The crown
Masonry
The concrete or stone slab on top of the brick, around the flue. A good crown slopes to shed water, overhangs the brick with a drip edge so water falls clear, and is sealed where it meets the flue liner. A crown that was just a thin layer of mortar feathered to the edge cracks in freeze-thaw, and water goes straight down into the brick and the chimney's core.
The cap and the flue top
Chimney
The cap is the metal hood or cover over the flue opening. Without one, rain falls straight down the flue and shows up in the firebox, on the damper, or at a cleanout door. A cap also keeps birds and animals out. If the flue liner is cracked, water that gets down the flue can soak into the surrounding brick.
The brick and mortar
Masonry
Brick and mortar absorb water, and water also gets in through hairline separations between the brick and the mortar joints. On a chimney that stands in the wind for decades, cracked or eroded joints and spalled brick faces let wind-driven rain into the core, and it can run down inside the chimney to the attic or the ceiling below.
The flashing
Roofing
The metal that seals the joint between the shingles and the brick: step flashing woven into the shingle courses along the sides, base flashing at the front, and counter flashing set into the mortar joints and lapped down over all of it. This is the roofer's part, and it is where most leaks at a chimney start.
How a chimney re-flash is doneThe cricket, or the lack of one
Roofing
A small peaked roof built on the uphill side of a wide chimney to split water and snow around it. Without one, the back of the chimney becomes a dam: leaves, water and in winter a pile of snow and ice sit against the brick, and the flashing there is under water every thaw.
Condensation in the flue
Venting
Not every wet chimney is a leak. Water that shows up only when the furnace or water heater is running, or white staining on an interior chimney wall, can be a venting problem. This is a question for a chimney professional or a heating contractor, not a roofer.
What You Can Check From the Ground and Inside the House
Look on a dry day, then again during or just after a long rain, and note what you see each time.
- Water in the firebox, on the damper, or rust on the damper plate: think top of the chimney first (cap, crown, flue).
- A stain on the ceiling or wall right beside the chimney chase, worst after storms: think flashing or the uphill side.
- Leaks only in wind-driven rain from one direction: the face of the chimney or the flashing on that side is the usual suspect.
- Leaks only during a thaw, with a pile of snow and ice behind the chimney: think missing or undersized cricket, and flashing buried in meltwater.
- Brick that stays dark for days after rain, white salt staining (efflorescence) on the outside, or brick faces popping off: the masonry is absorbing too much water.
- Through binoculars: a cracked crown, no cap on the flue, open mortar joints near the top, or metal glued flat to the face of the brick with a bead of caulk along the top, or tar smeared over the flashing. That is surface-mounted counter flashing or an old patch, and both are common failure points.
Stay off the roof. A chimney is usually near the ridge on a steep pitch, and a leak is not worth a fall. Binoculars and a look in the attic will tell you most of what a homeowner can learn.
Read the Attic: Where the Wet Stops Tells You a Lot
If you can safely get into the attic, the chimney usually passes right through it. Go during or just after a rain with a good flashlight, and step only on the framing.
- Step 1
Look at the Brick Itself
Find the chimney where it rises through the attic. If the brick is dark and damp well above the underside of the roof deck, water is coming down through the masonry, from the crown, the cap or the brick faces. Flashing cannot wet brick that sits above it.
- Step 2
Look at the Deck and Rafters Around the Chimney
If the brick is dry up high but the roof deck, framing or insulation is wet right where the chimney meets the deck, the water is getting in at the roof line. That points to flashing, or to the uphill side if the wet is worst there.
- Step 3
Check Which Side Is Worst
Wet on the uphill side only suggests a missing cricket or failed back flashing. Wet on one side only suggests the step flashing on that side, or wind-driven rain on that face. Wet all the way around suggests the whole assembly, or water coming from above.
- Step 4
Photograph and Note the Weather
Take photos with something for scale and note the date, how hard it rained, and which way the wind blew. A pattern across two or three storms often identifies the source before anyone touches the roof.
Remember that water travels. A drip that lands on the attic floor two feet from the chimney may have entered at the top of the brick and run down inside it. The attic narrows the list; it rarely closes the case on its own.
How a Professional Confirms the Source
When the clues are not conclusive, the reliable way to find a chimney leak is a controlled water test with someone watching inside. The rule is to start low and work up, one area at a time, so you know exactly which surface produced the water.
A typical sequence runs the hose at the front base flashing first, then each side, then the back of the chimney and the cricket, then the brick faces, and only last the crown and the top. Each area gets enough time to show a leak before moving up. Testing the top first is a common mistake: water poured on the crown can run down inside the brick and appear at the flashing line, making good flashing look guilty. A dry test does not clear the chimney either, since some leaks need a long soaker or a strong wind from one side.
Roofer, Mason or Chimney Sweep: Who Handles Which Part
Chimney leaks often go unfixed because each trade fixes its own part and assumes the rest is fine. It helps to know who owns what before you call anyone.
Roofer
Where the chimney meets the roof
Step flashing, base flashing, counter flashing, the cricket on the uphill side, the shingles and underlayment around the chimney, and any rotted decking beneath them. Stellar re-flashes chimneys with new metal and counter flashing cut into the mortar joints, but does not rebuild masonry; that work goes to a mason.
Chimney flashing repairMason
The brick and the crown
Rebuilding or replacing the crown, repointing cracked or eroded mortar joints, replacing spalled brick, and rebuilding a chimney top that has deteriorated. If the chimney leans or the brick is loose near the top, that is masonry work before anything else.
Chimney professional
The flue and the cap
Caps, flue liners, dampers, and inspection of the inside of the chimney. If water has been coming down the flue, the liner should be checked before the fireplace or any appliance is used again.
Heating contractor
Venting and condensation
If moisture appears only when an appliance runs, or a furnace was replaced and an older water heater still vents into the chimney, the venting needs a look. An oversized flue left behind by a furnace upgrade is a known carbon monoxide concern, which makes this a safety call, not a leak repair.
Why the Masonry Gets Fixed Before the Flashing
If both the brick and the flashing need work, the mason usually goes first. Proper counter flashing is set into a mortar joint, so if the joints are about to be ground out and repointed, or the top of the chimney rebuilt, new flashing would be disturbed or have to be redone. Once the masonry is sound, the roofer flashes into fresh, solid joints.
The exception is an active leak doing damage. A roofer can make a temporary repair to stop the water while the masonry work is scheduled, as long as everyone understands it is temporary.
Be wary of sprays and coatings sold as a one-step fix. The Brick Industry Association says water repellents cannot stop water through cracks wider than about 0.02 inch, should not be used in place of repointing and sealant repairs, need reapplication, and that film-forming coatings should not go on brick in freeze-thaw climates. If a repellent is used at all, it should be a breathable one, and only after the repairs are done.
What West Michigan Winters Do to Chimneys
Freeze-thaw is the reason chimney leaks here tend to get worse rather than stay steady. Water that soaks into a cracked crown or an open mortar joint freezes, expands and widens the gap, and the next rain gets in more easily. The top courses of brick and the crown take the worst of it because they are the most exposed.
Snow is the other half. Lake-effect snow drifts against the uphill side of a chimney, and on a wide chimney with no cricket that drift melts against the flashing on every sunny afternoon. Wind off Lake Michigan drives rain sideways into the brick faces, so a leak that only shows up in a west wind is common.
The masonry details are covered by Michigan's own rules too. Michigan's amendment to the chimney cap section of its residential code calls for a concrete, metal or stone cap sloped at least 10 degrees, at least 2 inches thick at the edge, overhanging the brick by at least 2 inches with a drip, with a bond break under a concrete cap and a sealed joint at the flue liner. A crown built that way sheds water. A flat, thin mortar crown does not.
Michigan's 2015 residential code remains in effect while a 2021 update is paused by a July 2025 court order. Confirm current requirements with your local building department before relying on any specific section.
What the Michigan Residential Code Requires Where a Chimney Meets the Roof
The roofing side of a chimney is not left to taste. The 2015 Michigan Residential Code sets minimums for crickets and chimney flashing in two chapters, and they are worth knowing before you compare repair quotes, because a quote that skips them is quoting less than the code asks for.
Crickets come up twice. Section R903.2.2 says a cricket or saddle "shall be installed on the ridge side of any chimney or penetration more than 30 inches (762 mm) wide as measured perpendicular to the slope," covered with sheet metal or the same material as the roof. The chimney chapter, R1003.20, says the same thing from the mason's side: a cricket is required where the chimney is more than 30 inches wide parallel to the ridge and does not intersect the ridge, and the joint between cricket and chimney must be flashed and counterflashed like any other roof to chimney joint.
R1003.20 also sizes the cricket. Its table sets the cricket's height as a fraction of the chimney's width: half the width on a 12:12 roof, a third on 8:12, a quarter on 6:12, a sixth on 4:12 and an eighth on 3:12. A 36 inch wide chimney on a 6:12 roof, for example, calls for a cricket about 9 inches tall. A token wedge of shingles a few inches high will not split a lake-effect drift.
The flashing itself has a floor too. Under R905.2.8.1, base flashing on a shingle roof must be corrosion-resistant metal at least 0.019 inch thick (or heavy mineral-surfaced roll roofing), and cap flashing, the counter flashing on the brick, must be corrosion-resistant metal of the same minimum thickness, installed to the manufacturer's instructions. When a roof is re-covered or replaced, R908.5 says existing flashings that are "rusted, damaged or deteriorated" shall be replaced, so old chimney metal should not simply be shingled back in.
The Michigan code rules that matter on a repair
Underlayment, ice barrier, flashing, reroofing limits and the line between a repair and a reroof, section by section.
Michigan code rules for repairsCode sections quoted from the 2015 Michigan Residential Code. A chimney that met the code in force when it was built is not automatically required to be brought up to these rules; ask your building department what applies when the flashing is redone.
Symptom, Likely Source, and Who Fixes It
| What you see | Most likely source | Usually fixed by |
|---|---|---|
| Water in the firebox or on the damper | Missing cap, cracked crown, or water down the flue | Chimney professional or mason |
| Wet brick in the attic above the roof deck | Crown, brick faces or mortar joints above the roof | Mason |
| Wet deck or rafters at the chimney base | Step, base or counter flashing | Roofer |
| Leak worst on the uphill side, during thaws | No cricket, or failed back flashing | Roofer |
| Leak only in wind-driven rain from one side | Brick face or side flashing on that side | Roofer or mason, after testing |
| Brick dark for days, white salt stains, flaking faces | Masonry absorbing water | Mason |
| Moisture only when the furnace or water heater runs | Venting or condensation in the flue | Chimney professional or heating contractor |
These are starting points for a diagnosis, not a substitute for one. One chimney can have more than one source.
Not Sure Whether It Is the Chimney or the Roof?
We inspect the flashing, the roof around the chimney and the attic, tell you which part is leaking, and say plainly when the fix belongs to a mason instead of a roofer. The inspection is free.
Related Guides
Why Roof Leaks Show Up Far From the Source
How water travels along the deck and framing before it drips.
Learn MoreHow Roofers Find Leaks
Visual tracing, attic checks, water tests and what each one misses.
Learn MoreFlashing Problems
Warning signs of failed flashing at chimneys, walls, vents and valleys.
Learn MoreFlashing Repair
How a chimney re-flash is built, and what it costs.
Learn MoreQuestions We Hear
Why is there water in my fireplace when it rains?
Water in the firebox or on the damper almost always comes from the top of the chimney, not the roof. The usual causes are a missing or damaged cap, a cracked crown, or water soaking through the brick near the top. Water inside a chimney can crack flue liners and rust dampers, so have a chimney professional inspect the cap, crown and liner before you use the fireplace again.
Do I need a chimney cricket?
It depends mostly on the chimney's width across the slope. The Brick Industry Association's chimney guidance calls for a cricket on chimneys wider than 30 inches across the slope that do not meet the ridge. Narrower chimneys can do without one, though in heavy snow country a cricket still helps. If your chimney is wide and leaks on the uphill side during thaws, ask your roofer about one when the flashing is redone.
Can a waterproofing spray stop my chimney from leaking?
Not on its own. The Brick Industry Association notes that clear water repellents cannot seal cracks wider than about 0.02 inch, are not a substitute for repointing or flashing repairs, and need to be reapplied. They can help brick that absorbs too much water once the real repairs are done, but only breathable products, and film-forming coatings should not be used on brick in freeze-thaw climates like Michigan's.
Will a new roof fix my chimney leak?
Only if the leak is in the flashing or the roof around the chimney, and only if the new roof includes new chimney flashing rather than reusing the old metal. A new roof does nothing for a cracked crown, a missing cap or porous brick. If the chimney needs masonry work, have it done before the roof goes on so the new flashing is set into sound mortar joints.
What This Page Cites
- Technical Note 19B: Residential Chimneys, Design and Construction, Brick Industry Association (https://inspectapedia.com/chimneys/Residential-chimneys-design-and-construction-BIA.pdf), accessed October 2026
- Technical Note 7: Water Penetration Resistance, Design and Detailing (November 2017), Brick Industry Association (https://www.gobrick.com/media/file/7-water-penetration-resistance-design.pdf), accessed October 2026
- Technical Note 6A: Colorless Coatings for Brick Masonry (August 2008), Brick Industry Association (https://www.gobrick.com/media/file/6a-colorless-coatings-for-brick-masonry.pdf), accessed October 2026
- Four Low-Cost Recommendations to Prevent Major Water Damage, Chimney Safety Institute of America (https://web.csia.org/news/newsarticledisplay.aspx?ArticleID=9), accessed October 2026
- Mich. Admin. Code R 408.30547b, Chimneys (amending R1003.9.1 chimney caps), via Legal Information Institute (https://www.law.cornell.edu/regulations/michigan/Mich-Admin-Code-R-408-30547b), accessed October 2026
- 2015 Michigan Residential Code, Chapter 9 Roof Assemblies, Sections R903.2.2, R905.2.8.1 and R908.5, UpCodes (https://up.codes/viewer/michigan/mi-residential-code-2015/chapter/9/roof-assemblies), accessed October 2026
- 2015 Michigan Residential Code, Chapter 10 Chimneys and Fireplaces, Section R1003.20 and Table R1003.20 Chimney Crickets, UpCodes (https://up.codes/viewer/michigan/mi-residential-code-2015/chapter/10/chimneys-and-fireplaces), accessed October 2026
- Bureau of Construction Codes rules currently open, Part 5 Residential Code status and July 7, 2025 Court of Claims order, Michigan LARA (https://www.michigan.gov/en/lara/bureau-list/bcc/rules-acts/rules/currently-open), accessed October 2026
- Condensing vs. Non-Condensing Gas Appliances: Orphaned Water Heater (workshop presentation, October 2014), U.S. Department of Energy (https://www.energy.gov/sites/prod/files/2014/10/f18/October%209th%20Workshop%20Presentation%20-%20Kevin%20Dunn.pdf), accessed October 2026