Roof problems
Roof leaking around the chimney: causes and fixes
Most leaks around a chimney come from failed flashing, the metal that seals the joint between the chimney and the roof. Cracked mortar, a damaged chimney crown or a missing cap can also let water in. A lasting fix replaces the step and counter flashing, and on a chimney more than 30 inches wide that sits below the ridge, the building code also calls for a cricket, a small peaked diverter that sends water around the chimney. A full chimney reflash is part of our Core and Complete options.
Updated October 3, 2026
- What it looks like
- A stain on the ceiling or wall beside the chimney, damp or white-streaked brick in the attic, or water running down the chimney during heavy rain.
- What it usually means
- Usually failed step or counter flashing. Less often, cracked mortar, a cracked crown or a missing cap.
- How urgent
- Get it fixed before winter. Water at a chimney soaks the framing around it, and freeze and thaw widen the gaps.
- What to do next
- Photograph the stain and the outside of the chimney from the ground. If the roof is older, see a replacement price with a full chimney reflash at thethomasroofing.com, or call Thomas Roofing at (860) 710-5862.
Where the water gets in
- Step flashing: the L-shaped pieces woven into each course of shingles along the sides of the chimney
- Counter flashing: the metal set into the mortar joints that covers the step flashing
- The crown: the concrete cap on top of the chimney, which cracks over time
- Mortar joints and brick, which absorb more water as they age
How to tell what’s leaking
If the stain appears only during heavy, wind-driven rain, flashing is the usual suspect. If the brick looks damp or streaked white from the outside, or the leak shows up after long, steady rain, the masonry or the crown is more likely. A leak on the downhill side of the chimney often means water is getting behind the flashing on the uphill side.
Why sealant doesn’t last
Caulk and roofing cement over old flashing can stop a leak for a season, but they dry out and crack as the chimney and the roof move differently with temperature. Replacing the flashing when the roof is replaced is the durable fix, and it costs less than doing it separately later.
What the building code requires at a chimney
- Step flashing against every vertical sidewall, which includes the sides of a chimney, so water is turned back onto the roof (Connecticut State Building Code R905.2.8.3)
- Chimney, wall and vent flashing installed to the shingle manufacturer’s instructions (Connecticut State Building Code R905.2.8.4)
- A cricket on the uphill side of any chimney more than 30 inches wide along the ridge line that doesn’t sit on the ridge itself, flashed and counter flashed like the rest of the chimney (International Residential Code R1003.20)
Questions
- Can chimney flashing be fixed without replacing the roof?
- Sometimes, on a younger roof. If your roof is near the end of its life, reflashing now disturbs shingles that will be replaced soon anyway, so doing both together usually makes more sense.
- What if the problem is the chimney itself?
- Our roofing options cover the flashing. If the verification visit finds crown or mortar problems, we photograph them and tell you before you sign.
- Do I need a chimney cricket?
- If your chimney is more than 30 inches wide along the ridge line and doesn’t sit on the ridge, the building code calls for one, because without it water and snow collect behind the chimney.
Sources
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