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Homeowners usually call a chimney contractor after noticing crumbling bricks, a stain on the ceiling beside the chimney, rust on a metal cap or a chimney that no longer looks straight. Others are sent by a chimney sweep, an insurer or a home inspector who flagged a cracked crown, a damaged liner or an installation that isn't up to code. The work ranges from sealing a crown or replacing flashing to repointing, relining, rebuilding the top of the chimney or taking down one that's no longer used.
This page explains the problems that affect masonry chimneys, what liners do, how water causes most of the damage, and how repairs relate to sweeping and to safety inspections for wood stoves and fireplaces. Chimney work means working at height on a roof, so it's a job for qualified masons and chimney specialists, not a weekend project.
Common masonry chimney problems: spalling, cracked crowns, failed flashing and leaning
Some of these problems are first noticed on the roof during shingle work, and chimney flashing is often redone jointly by the roofer and the mason.
- Spalling: brick faces that flake, pop off or crumble when water soaked into the masonry freezes and expands.
- Deteriorated mortar joints: sandy, recessed or missing mortar that lets water into the chimney and loosens bricks over time.
- Cracked or crumbling crown: the sloped concrete or mortar slab at the top of the chimney, which lets water straight into the masonry once it cracks.
- Failed flashing: step and counter flashing that has lifted, rusted or lost its seal where the chimney passes through the roof.
- Leaning or separating chimney: a stack that tilts or pulls away from the house, often from footing problems or long-term water damage, which needs prompt assessment.
- Damaged cap and damper: a missing or rusted rain cap lets in water, birds and debris, and a rusted damper may no longer open or close fully.
Signs your chimney needs repair, seen from the ground and from inside
You can spot many warning signs without going up on the roof. Look at the chimney from the ground or a window, with binoculars if needed, and check inside around the fireplace or appliance.
- Pieces of brick, mortar or tile on the roof, in the gutters or on the ground below the chimney.
- White, powdery deposits on the bricks, a sign that water is moving through the masonry.
- Water stains or peeling paint on ceilings and walls next to the chimney, or damp spots around it in the attic.
- Water, rust flakes or debris in the firebox, or a damper that sticks.
- A chimney that looks tilted, or a gap opening between the chimney and the house wall.
- Smoke spilling into the room or a strong creosote smell, especially in humid weather.
How water and freeze–thaw cycles damage a chimney
Water is behind most chimney repairs. Brick and mortar absorb it, and when that water freezes in winter it expands and breaks the masonry apart from within, a little more with each cycle. A cracked crown or a missing cap lets rain and snowmelt pour straight into the chimney, and failed flashing lets it run into the roof framing, the attic and the ceilings below.
Inside the flue, water mixes with combustion deposits to form acidic compounds that eat at mortar and clay liners and rust metal parts. Moisture trapped in a chimney that no longer serves an appliance can do the same damage slowly. That's why a good repair focuses first on keeping water out: a sound crown with a drip edge, a proper cap, tight flashing and, where the contractor recommends it, a breathable water repellent made for masonry.
Chimney liners: why the flue lining matters
The liner is the inner flue that contains heat, smoke and condensation and protects the surrounding masonry and the house framing. Older chimneys sometimes have no liner at all, or clay tiles that have cracked or shifted over the years. A sweep or inspector can usually spot liner damage with a camera or during a sweep.
- Clay tile liners: common in masonry chimneys, durable while intact but prone to cracking in a chimney fire or with sudden heat.
- Stainless steel liners: flexible or rigid pipe slid down the existing flue, a common way to reline an old chimney or connect a new appliance.
- Cast-in-place liners: a lightweight cement mix poured around a form inside the flue, which can also add strength to an old chimney.
- Relining is often needed when the appliance changes, such as a new wood stove or an old furnace being replaced, because the flue must suit the appliance it serves.
Repointing, rebuilding or removing a chimney
- Seal or rebuild the crown when it's cracked but the masonry below is sound.
- Repoint when mortar joints have eroded but most bricks are intact, using a mortar compatible with the age and type of brick.
- Replace damaged bricks one by one when spalling is limited to a few spots.
- Rebuild the top of the chimney, down to the roofline or below, when spalling and loose bricks are widespread there.
- Have a mason or an engineer assess a leaning chimney before any work, since it may need to be rebuilt from a sound base.
- Consider removing a chimney that no longer serves any appliance, which also removes a source of leaks, after confirming it doesn't vent a furnace or water heater.
How a chimney repair job works
- Inspection: the contractor examines the chimney from the roof and from inside, often with a camera in the flue, and may ask for a recent sweep first.
- Written scope: crown, cap, flashing, brick and mortar work or relining, with photos of what they found.
- Access and protection: ladders, roof anchors or scaffolding set up safely, and the roof, landscaping and fireplace opening protected from debris.
- Masonry work: removing damaged mortar and brick, repointing and rebuilding, then forming or sealing the crown.
- Weatherproofing: installing or resealing flashing, often with the roofer, and fitting a new cap.
- Final check: a look at the flue and the appliance connection, advice on curing time before lighting a fire, and cleanup.
Wood-burning appliance inspections: WETT in Canada and qualified sweeps in Quebec
When a wood stove, fireplace or chimney is installed, comes with a house you're buying or is raised by an insurer, you may be asked for a safety inspection. In most provinces, the reference is the WETT program, run by Wood Energy Technology Transfer Inc., a non-profit training and education association that acts as the national registrar for wood-energy professionals. WETT-certified inspectors check whether a wood-burning appliance and its venting system were installed to building and fire code requirements, and insurers often ask for this kind of inspection.
In Quebec, the provincial government advises having the chimney swept at least once a year, ideally in spring while the deposits are dry, by a professional who holds the appropriate licence from the Régie du bâtiment du Québec, and having the system inspected every year, before the heating season, by a member of the Association des professionnels du chauffage. Repairs that come out of these inspections, such as a new liner or crown, should go to a qualified mason or chimney contractor, and your municipality may require a permit to rebuild or remove a chimney.
Chimney sweeping versus chimney repair: who does what
Book the sweep first when a wood-burning appliance is in use: a clean flue reveals the cracks and gaps that soot hides, and the sweep's report tells the mason what needs fixing.
- A chimney sweep removes soot and creosote from the flue, checks the cap, damper and liner and reports defects; in Quebec, look for a member of the Association des professionnels du chauffage.
- A mason or chimney contractor repairs the crown, bricks, mortar and liner, and rebuilds or removes chimneys.
- A roofer handles the roof around the chimney and often works with the mason on the flashing.
- A WETT-certified inspector, or in Quebec a qualified heating professional, assesses whether a wood-burning installation meets code, for example before a sale or for an insurer.
- A heating contractor deals with the chimney connection for oil or gas appliances and with any change of appliance or fuel.
Chimney Repair: frequently asked questions
How often should a chimney be swept and inspected?
Quebec's government recommends sweeping at least once a year, ideally in spring, and having the system inspected every year before the heating season. Burning a lot of wood, or wood that isn't dry, can make more frequent sweeping necessary.
What is a WETT inspection?
It's a safety inspection of a wood-burning appliance and its venting, done by a professional certified through the WETT program, to check that the installation meets building and fire code requirements. Insurers and buyers often ask for one.
Can I use my fireplace if the chimney crown is cracked?
A cracked crown is mainly a water problem, but the water it lets in can loosen bricks and damage the liner over time. Have it assessed soon, and stop using the appliance if the sweep or inspector finds liner damage.
What should I do after a chimney fire?
If you suspect a chimney fire, get everyone out and call 911. Afterwards, don't use the appliance again until a sweep or inspector has checked the flue and liner, since the intense heat can crack tiles and mortar even when nothing looks wrong from outside.
Should I remove a chimney I no longer use?
It can make sense, since an unused chimney still needs upkeep and can still leak. First confirm that it doesn't vent a furnace or water heater, and ask your municipality whether a permit is required.
Can I check my chimney myself?
Only from the ground or from inside the house. Looking for fallen brick, stains and rust is safe; going up on the roof or into the flue is a job for a professional with the right equipment.
Sources
Written by the LokalMatch editorial team. Reviewed by Zubair Afzal on September 10, 2026. How we write and check our guides