About Our Chimney Repair Service
A damaged or deteriorating chimney can allow water ingress into your home and in serious cases poses a structural risk. Our team are experienced in all aspects of chimney repair, from repointing crumbling mortar joints to complete stack rebuilds.
Repointing
Over time mortar joints between bricks erode, allowing water to penetrate the stack. We rake out old mortar and repoint with a durable weather-resistant mix, restoring the chimney's weatherproofing and appearance.
Flashing Repairs
Lead flashings seal the junction between the chimney and the roof slope. Failed or lifted flashings are a common cause of roof leaks. We repair or replace lead step flashings and back gutters correctly and permanently.
Stack Rebuilds
Where a chimney stack is badly deteriorated, leaning or structurally unsound, a partial or full rebuild may be required. We rebuild chimneys in matching brick with correctly formed flaunching and new pots or cowls.
Pot & Cowl Fitting
We can supply and fit a wide range of chimney pots, anti-downdraught cowls and bird guards. Whether replacing a damaged pot or adding a cowl to resolve downdraught issues, we handle it safely from scaffold.
Where Chimney Leaks Actually Come From
A damp patch on a chimney breast is one of the most common call-outs we get across Sunderland, and the cause is rarely what people assume. It's almost never the pots. Working down from the top, here's what actually fails.
Cracked flaunching
Flaunching is the sloped bed of mortar on top of the stack that holds the pots in place and sheds water off the top. It's exposed to everything and it's usually the first thing to go. Once it cracks, rain runs straight down the outside of the flue inside the stack. It's cheap to renew and expensive to ignore — a lot of the stacks we end up rebuilding started as failed flaunching that let water into the brickwork for a decade.
Eroded pointing
The mortar joints in the stack brickwork erode faster than anywhere else on the building, because a chimney is the most exposed masonry you own — wind and rain hit it from every side with nothing sheltering it. Near the coast, salt accelerates the breakdown. Inland and to the west it's freeze-thaw: water soaks into the joints, freezes overnight, expands and breaks the mortar apart, winter after winter. Repointing in good time is far cheaper than a rebuild.
Failed lead flashings — the most common culprit
Where the chimney passes through the roof there should be a proper set of lead flashings: an apron at the front, stepped flashings and soakers up the sides, and a back gutter behind. Done properly in lead, that lasts decades. The problem is how often we find cement fillets used instead — a wedge of mortar smeared into the junction. Cement is rigid, the roof and stack move at different rates, and it cracks within a few years. If you've got a leak near a chimney, this is the first place we look.
Salt damp on old flues
Worth knowing about because it gets misdiagnosed constantly. A flue that burned coal for decades has hygroscopic salts left in the brickwork by the soot. Those salts pull moisture out of the air, so you get damp patches that come and go with humidity rather than with rainfall. If your chimney breast is damp in dry weather, water ingress may not be the problem at all — and no amount of repointing will fix it.
Repoint, Rebuild or Remove?
Repointing
The right answer when the bricks themselves are sound and only the mortar joints have eroded. We rake the failed joints out properly and repoint — not a skim over the top of what's there, which looks fine for a season and then falls out.
Rebuilding the stack
Necessary once the bricks have spalled and started crumbling, the stack is visibly leaning, or the mortar has gone so soft there's nothing holding the courses together. We take it down to a sound course and rebuild, reusing salvageable brick where it matches. On a badly exposed stack we'd rather rebuild once than repoint something that won't hold — and we'll tell you that up front rather than taking the smaller job and coming back.
Capping off a redundant flue
If you've no intention of using the fireplace again, capping the chimney stops water and birds getting in. The critical detail — and the one most often got wrong — is that a capped flue still has to breathe. Seal it completely and you trap moisture inside, which reappears as damp on the chimney breast within a year or two. We fit a vented cap or cowl that keeps rain out while letting air move.
Removing the stack
Where a chimney is redundant and in poor condition, taking it down can be the most economical option — either to roof level with the roof made good over it, or lower. It removes a maintenance liability permanently. Worth thinking about if you're having a roof replacement anyway, since the scaffolding is already up.
Pots, caps and cowls
We fit replacement pots, rain caps, vented caps for capped flues, and anti-downdraught and bird-guard cowls. The important part is bedding a new pot into fresh flaunching rather than patching around the old cracked mortar — which is why a cheap pot swap so often fails within a couple of winters.
What's Included
- Free survey and no-obligation quotation
- Full chimney repointing
- Lead step flashing repair or replacement
- Lead back gutter repair or replacement
- Flaunching repair or replacement
- Chimney pot replacement
- Anti-downdraught cowl fitting
- Bird guard installation
- Partial chimney rebuild
- Full chimney stack removal
- All work carried out from scaffold
- Full site clearance on completion
Chimney Repair FAQs
Why is damp appearing on my chimney breast?
Three causes account for most of it. Cracked flaunching — the sloped mortar cap holding the pots — lets water straight down the outside of the flue. Failed pointing in the stack brickwork soaks the masonry. And failed lead flashings where the chimney meets the roof let water in at that junction, which is the most common of the three. On an old flue that's burned solid fuel there's a fourth possibility: hygroscopic salts left in the brickwork by soot draw moisture out of the air, producing damp patches that come and go with the weather rather than with rainfall.
Does my chimney need repointing or rebuilding?
Repointing is enough when the bricks themselves are sound and it's only the mortar joints that have eroded. A rebuild becomes necessary when the bricks have spalled and crumbled, when the stack is visibly leaning, or when the mortar has gone so soft there's nothing left holding the courses together. We'll tell you which after inspecting it, and on an exposed stack we'd rather rebuild once than repoint something that won't hold.
Can you cap off a chimney we no longer use?
Yes, and it's a sensible thing to do with a redundant flue, but it has to be ventilated. Sealing a flue completely traps moisture inside it, and that shows up as damp on the chimney breast within a year or two. We fit a vented cap or cowl that keeps rain out while letting the flue breathe. If you'd rather remove the stack altogether we can take it down to roof level and make good, or lower.
How often do chimney flashings need replacing?
Good lead flashing installed properly lasts decades, often the life of the roof covering. What fails sooner is cement fillets used instead of lead, which crack within a few years, and lead that was dressed badly or fixed without allowing for expansion. If you have a leak near a chimney breast, the flashings are the first thing we check.
Why do North East chimney stacks deteriorate so fast?
A stack is the most exposed masonry on the building — it catches wind and rain from every direction with no shelter. Near the coast, salt-laden air accelerates the breakdown of mortar. Inland and to the west, freeze-thaw does the damage: water soaks into the mortar and the brick face, freezes, expands and breaks it apart over repeated winters. Either way the stack usually needs attention well before the rest of the roof does.
Do you fit chimney pots and cowls?
Yes. We fit replacement pots, rain caps, vented caps for capped-off flues, and anti-downdraught and bird-guard cowls. Fitting a pot properly means rebedding it into fresh flaunching rather than patching around the old cracked mortar, which is why a cheap pot replacement often fails within a couple of winters.
Chimney Repairs Across the North East
We carry out chimney repairs, repointing and stack rebuilds across Sunderland, Tyne and Wear and County Durham.