Chimney leaks usually come from failed flashing where the chimney meets the roof, a cracked crown at the top, porous or cracked masonry, or a missing cap. Flashing work is a roofing repair, while masonry and crown repair may need a mason, so the first step is to find out which it is.
The five usual suspects
| Source | What goes wrong | Who usually fixes it |
|---|---|---|
| Base flashing and counterflashing | Metal rusts or lifts; sealant fails; counterflashing pulls out of the mortar | Roofer (see flashing repair) |
| Chimney crown (the top slab) | Cracks let rain run down into the chimney structure | Mason or chimney specialist |
| Brick and mortar | Mortar joints erode and bricks absorb water | Mason; sometimes sealed with a breathable water repellent |
| Chimney cap or rain cover | Missing or damaged; rain falls straight down the flue | Chimney specialist or roofer |
| The saddle (cricket) | Wider chimneys need a small peaked structure on the uphill side to deflect water; if it’s missing or poorly flashed, water collects | Roofer |
Signs your chimney is the culprit
- Brown stains on the ceiling or wall next to the chimney
- Dampness or water dripping inside the fireplace or firebox
- White powdery deposits (efflorescence) on the chimney exterior, which signals moisture moving through the masonry
- A musty smell near the fireplace that gets stronger after rain
- Leaks that only appear in wind-driven rain
What the inspection looks like
A roofer will check the flashing and the area around the chimney from the roof and look at the attic side if accessible. If the flashing looks fine but the stonework is cracked or the crown is deteriorated, they’ll tell you that, and you may need a chimney or masonry specialist. Being clear about this up front is a sign of a straightforward contractor.
Repairs, in order of effort
- Re-sealing minor flashing gaps as a temporary measure
- Replacing or re-setting flashing and counterflashing properly
- Installing or repairing a chimney cap
- Repairing or rebuilding the crown
- Repointing mortar joints and applying a masonry sealer where appropriate
- Building a saddle behind a wide chimney
Before the next rain
If water is coming in around a fireplace and it’s raining, a temporary cover may help. A tarp over the chimney top can prevent rain entering the flue, but it must be secured safely and never left on during fireplace use. For help placing temporary protection, read the page on emergency roof tarping.
Do not light a fire in a fireplace with a damaged or covered chimney, or one that has recently leaked, until it has been checked. Water damage can affect the flue and combustion gases can back up if the chimney is blocked or compromised.
For an overview of how roof leak calls are handled in general, see how we connect callers for professional roof leak repair. If your home has a fireplace, the Almond-Shuey page walks through a chimney leak zone by zone.
Chimney leak questions
Is a chimney leak a roofer’s job or a mason’s?
Both can be involved. Flashing and saddles are roofing work; crowns, brick and mortar are masonry. A good first inspection should identify which applies.
Why does my chimney only leak during heavy rain?
That often means a small gap in the flashing or crown that only lets water through when it’s pushed by wind or runs in volume. Intermittent leaks are still worth fixing.
Will a water repellent on the bricks stop the leak?
It can reduce absorption through masonry but won’t fix failed flashing or a cracked crown. Use breathable products and identify the actual source.
How urgent is a chimney leak?
Treat active leaks as urgent. Water that sits against framing and insulation can rot wood and cause mold over time.
Related services
Water near the chimney?
Call to be connected with an independent roofer who can find where it’s coming in.