It rained last night, and this morning there is water in the firebox, a damp smell by the fireplace or a new stain on the ceiling next to the chimney. A leaking chimney is one of the most common calls we get in the fall, and the good news is that the cause can almost always be found and fixed. In this guide we explain the signs of a leak, the five places water usually gets in, what to do right away and how we repair it.
Signs Your Chimney Is Leaking
Some leaks are obvious. Others take months to show up. Look for any of these:
- Water or wet ash in the firebox after rain
- Dripping or a tapping sound inside the chimney when it rains
- Stains on the ceiling or the wall next to the chimney
- A damp, musty smell from the fireplace, especially after a storm
- Rust on the damper, the firebox doors or the top of a metal chimney
- White powder on the brick, inside or outside
- Brick faces that crack, flake or pop off
- Wet or dark wood in the attic around the chimney
If you see more than one of these, water has probably been getting in for a while. In that case, the sooner the chimney is inspected, the smaller the repair usually is.
Where the Water Gets In
A chimney sticks up through the roof and takes the full force of the weather. As a result, there are only a few places where water gets in, and a good inspection checks every one of them.
1. A Missing or Damaged Chimney Cap
Without a cap, rain falls straight down the flue into the firebox. A rusted or loose cap does the same, and it also lets in birds and squirrels. This is the most common cause of water in the firebox, and it is also the simplest fix. We measure and install a custom chimney cap made to fit your chimney.
2. A Cracked Chimney Crown
The crown is the concrete slab on top of a masonry chimney. Its job is to shed water away from the flue. Over time, our hot summers and freezing winter nights crack it, and every crack lets water into the chimney below. Small cracks can be sealed. However, a crown that is broken or badly built needs to be rebuilt. Read more about chimney crown repair.
3. Failed Flashing
Flashing is the metal that seals the joint between the chimney and the roof. When it lifts, rusts or the sealant dries out, water runs down the outside of the chimney and into the house. A leak from flashing usually shows up as a stain on the ceiling or wall next to the chimney rather than in the firebox. See our chimney flashing repair page.
4. Brick and Mortar That Soak Up Water
Brick and mortar are porous. When the mortar joints wear out or the brick starts to break down, wind-driven rain soaks straight through the wall of the chimney. That is why some chimneys only leak in heavy storms. The fix is to repair the brick and mortar and then waterproof the chimney. Learn more about our chimney leak repair and waterproofing and masonry repair.
5. A Rusted Chase Cover or Damaged Siding
Many newer homes have a wood-framed chimney covered in siding instead of brick. The metal cover on top, called the chase cover, rusts through over the years or holds a puddle of water in the middle. Meanwhile, water also gets in behind damaged siding. Either way, the wood frame inside starts to rot. We repair the siding and replace the chase cover. See our chimney siding repair page.
Not Every Wet Chimney Is a Rain Leak
Sometimes moisture inside the chimney comes from condensation, not rain. This happens most often with gas appliances venting into an old masonry flue that was never relined. If the chimney is damp even in dry weather, condensation is a likely cause, and the fix is usually a chimney liner.
Is It the Roof or the Chimney?
Homeowners often ask whether they need a roofer or a chimney company. Here is a quick way to think about it:
- Water inside the firebox: almost always the chimney, usually the cap or the crown.
- Stain on the ceiling right next to the chimney: usually the flashing, which is where the roof and the chimney meet.
- Leak only in heavy, wind-driven rain: often the brick, the mortar or the flashing.
- Stain far from the chimney: most likely the roof itself.
In short, if the water shows up at or next to the chimney, start with a chimney inspection. We check the chimney and the flashing around it, and if the problem is the roof, we tell you that.
What to Do Right Now
Until the chimney is repaired, a few simple steps limit the damage:
- Put towels or a pan in the firebox to catch the water.
- Keep the damper closed when the fireplace is not in use.
- Take photos of any stains, so you can see whether they grow.
- Do not use the fireplace if the firebox or the flue has been soaking wet. Wet masonry and a damaged flue are not safe to fire.
- Do not climb on the roof to look. A wet roof is slippery, and we have the equipment to do it safely.
How We Find and Fix the Leak
Every repair starts with an inspection, because guessing at a leak is how homeowners end up paying twice. During our Full Chimney and Fireplace Inspection, we check the cap, the crown, the flashing, the brick, the mortar and the inside of the chimney. You get a written report with photos from the roof and from inside the house, and a written estimate for the repair.
Then you decide. We never start any work without your approval. Our repairs come with warranties from 1 to 10 years, depending on the work.
Fall is the right time to fix a leak. Winter rain and freezing nights in North Texas make cracks in the crown and the brick bigger, so a small repair now often prevents a much bigger one in spring.
Frequently Asked Questions
Why does my chimney only leak in heavy rain?
Light rain runs off the chimney. Heavy, wind-driven rain is pushed into worn mortar, porous brick and gaps in the flashing. That is why a chimney can stay dry for months and then leak in one big storm.
Will a chimney cap stop the leak?
It will stop rain from falling down the flue, which is the most common cause of water in the firebox. However, a cap does not fix a cracked crown, failed flashing or worn mortar. That is why we inspect the whole chimney before recommending a repair.
Can I seal the chimney myself?
You can buy masonry sealer, but sealer on top of cracked brick, bad mortar or failed flashing will not stop the leak. Also, the wrong sealer can trap moisture inside the brick and make the damage worse. Repair first, then waterproof with a product made for masonry.
How much does chimney leak repair cost?
It depends on where the water is getting in. A new cap and a full crown rebuild are very different jobs. Our inspection is $49, and you get a written estimate before any work starts.
Is a leaking chimney dangerous?
Over time, yes. Water breaks down the mortar, rusts the damper and can damage the flue liner. In addition, wet wood around the chimney rots, and damp areas can grow mold. A small leak is much cheaper to fix than the damage it causes.
Get Your Leaking Chimney Inspected
We find and fix chimney leaks for homes in Dallas, Richardson, Carrollton, Garland, Arlington, Plano and Fort Worth. Call us at (214) 550-3348 or book a chimney inspection online. For more on how chimneys are inspected, the Chimney Safety Institute of America has a helpful guide.
