Chimney repair cost dataset

Required height, by pitch and position

3 feet above the roof penetration, and 2 feet above anything within 10 feet horizontally. On a slope, that something is the roof. So the height is max(3, rise over 10 feet + 2).

Read any row across: the requirement climbs as the chimney moves away from the ridge, then flattens once it is more than 10 feet away and the radius stops reaching further up the roof. ⚠️ Trade practice rather than a standard reproduced here — the rule appears in copyrighted documents this project does not republish, and your local code is the authority. It is set out because it is one of very few things on a chimney quote that can be checked with a tape measure, and because rebuilding a short chimney back to its short height is paying twice.

Eight jobs, one name

A factor of 24 between fit a rain cap and spark arrestor and rebuild the whole chimney from the ground. ⚠️ The two cheapest rows are priced off a ladder and the rest are priced off a platform, which is not a modelling convenience: a mason needs both hands, somewhere level to stand and somewhere to set mortar down. Each job also carries its own hours per square foot of masonry, because repointing a joint and laying new brick do not run at the same rate.

Access, and what the pitch does to it

The pitch appears twice and for two different reasons: it slows the work down, and it makes the chimney taller. Both effects are real and they are kept separate in the model so the page can explain them separately.

Why the flashing is not here

The commonest actual cause of water appearing near a chimney is the flashing where it meets the roof, and that is deliberately not priced on this page. It is a roof leak rather than a chimney fault, it is roofer work rather than mason work, and it is priced on our roof repair dataset with its own hours. Pricing it in both places would be the same intention on two URLs, and it would let the two pages drift into quoting different figures for the same work. ⚠️ It is also worth ruling out before paying for masonry: new flashing is far cheaper than repointing, and it fixes the leak far more often.

Line items

68% of the reference total comes from estimated rather than official figures. The reference job is repointing 40 square feet of masonry on a chimney with a 10-foot perimeter standing 4 feet above a 6:12 roof, 8 feet from the ridge — which by the trade rule wants 6 feet up there.

The reasoning behind each figure

Inspection and mobilisationestimated, ±45%

• Getting a mason, a van and materials to the house, plus the look at the chimney that has to happen before anything is priced properly.
• ⚠️ A camera inspection of the flue is a different and more thorough thing, usually charged separately, and it is what tells you whether the clay liner is cracked. Nobody can see that from the roof.

Stainless rain cap and spark arrestorestimated, ±60%

• One per flue. Stainless or copper, sized to the flue and fixed rather than friction-fitted.
• The cheapest preventive item on this page by a wide margin: an uncapped flue takes rain straight into the masonry, and water freezing inside brickwork is the mechanism behind most of the expensive lines below.

Reinforced concrete crown with an overhangestimated, ±41%

• Cast in place with reinforcement, a slope away from the flue and an overhang past the brick with a drip edge — which is what the thin mortar wash on most chimneys does not have.
• ⚠️ A crown is not a mortar parge coat, and the two are frequently confused on a quote. If the price looks like a couple of bags of mortar, it is a couple of bags of mortar, and it will crack again in the same three years.

Mortar, grinding discs and consumablesestimated, ±44%

• Priced by square foot of chimney face repointed. Mortar is cheap; the diamond blades that grind the old joints out are not, and they are consumed.
• ⚠️ On soft old brick the right mortar is a softer lime mix, which costs more and is not what arrives on a standard truck. Getting this wrong is the repair that destroys the brick it was meant to protect.

Brick, block, mortar and flue tileestimated, ±42%

• Priced by square foot of chimney face rebuilt, including the flue tile inside it.
• ⚠️ Matching brick on an old house is its own problem and the honest answer is that it usually cannot be matched exactly. Reclaimed brick of the right period is the best result and it is dearer than new. A rebuilt section in obviously new brick is a permanent visual repair.

Firebrick and refractory mortarestimated, ±51%

• Firebrick and the refractory mortar that goes with it, which is a different material from ordinary mortar and behaves differently at temperature.
• The firebox is the wall between the fire and the timber frame of the house, which is why open joints in it are not a cosmetic question.

Insulated stainless steel flue linerestimated, ±42%

• Continuous stainless liner with an insulation blanket, a top plate and a connector at the appliance, priced by the foot of flue and multiplied by the number of flues.
• ⚠️ An old open-fireplace flue is far too large for a modern gas or wood appliance. The gases cool on the way up, condense, and the moisture attacks the masonry from the inside — which is why relining is so often part of a conversion rather than an upsell.

Breathable masonry water repellentestimated, ±44%

• Vapour-permeable repellent, applied to saturation on clean sound masonry.
• ⚠️ Breathable is the whole specification. A film-forming sealer traps moisture inside the brick and accelerates the spalling it was bought to prevent.

Masonry work

• A base allowance for the kind of job plus 0.42 hours per square foot of face worked, scaled by the pitch factor of the roof it stands on.
• Working on a chimney is slower than the same brickwork at ground level for reasons that have nothing to do with skill: every brick and every bucket goes up a ladder or a hoist, and there is nowhere to put anything down.
• Increased by 35% on a pre-1978 house, where disturbing painted trim around the chimney brings the job inside the federal lead programme.

Liner and cap fitting

• Dropping and connecting a liner, or fitting caps. Uses the BLS occupation for sheet metal workers, which is the closest published trade to this work.
• ⚠️ A declared substitution: much of this is done in practice by chimney sweeps and specialist firms, and the BLS publishes no occupation for them. The regional multiplier is the strong part of our wage model and the absolute rate the weak part, and that is more true here than on most pages.

Access — ladders and roof jacksestimated, ±56%

• Ladders, stand-offs and roof jacks. Enough for fitting a cap or spraying a repellent, and not enough for laying brick.

Access — scaffolding around the chimneyestimated, ±55%

• Scaffold erected around the chimney and tied, left up for the days the work takes.
• ⚠️ Not optional for masonry. A mason needs both hands, a level platform and somewhere to set mortar down, and none of those exist on a ladder.

Access — a boom lift or crane accessestimated, ±45%

• A boom lift hired with a delivery and a collection, for a chimney that scaffold cannot reach economically.
• It also solves a problem people forget: brick and mortar are heavy, and on a tall house getting them up there is its own job.

Erecting and striking access

• One hour with ladders, six with scaffolding, three with a lift that arrives assembled.
• Scaffolding around a chimney is fiddlier than a straight elevation: it has to be tied, it has to clear the roof, and it has to leave the mason able to work all four sides.

Debris removal and protectionestimated, ±73%

• Sheeting the roof below so falling brick does not damage it, and taking the rubble away. A rebuilt chimney produces a surprising amount of it, and all of it lands on a roof first.

Not included in this dataset

The flashing where the chimney meets the roof

That is a roof leak rather than a chimney repair, it is roofer work rather than mason work, and it is priced on our roof repair page. ⚠️ It is also the commonest actual cause of water appearing near a chimney, so it is worth ruling out before paying for masonry.

Sweeping and camera inspection

A level-two inspection with a camera down the flue is what tells you whether the clay liner is cracked, and it is charged separately by a certified sweep. It should come before a quote for relining rather than after.

The appliance

A wood stove, an insert or a gas log set is its own purchase and its own installation. What this page prices is the chimney around it.

Foundation movement under the chimney

⚠️ A chimney leaning or pulling away from the house has a problem below it, not in it. Rebuilding the stack without fixing what is underneath buys a few years at full price. Our foundation repair page prices the other half.

Taking the chimney down entirely

Where the fireplace is no longer used, demolishing the stack to below the roofline and roofing over it is often far cheaper than any repair here, and it is an option almost nobody is offered. It is a roofing and framing job rather than a masonry one.

What your insurance will pay

Storm damage and gradual deterioration are treated differently by most policies, and which one a cracked crown is counts as a judgement made on your chimney. This page prices work; it does not advise on claims.