Rebuilding a chimney stack: when repair is no longer enough

A repair works when the structure under it is sound, which is the test we apply at every survey. Pointing grips good brick, new lead seals against good masonry, a fresh cap sits on a solid stack. The cases below are the ones where that is no longer true.

A stack that leans or moves

A lean you can see from the street, a gap opening between the stack and the roof, or a crack running across several courses all point to movement. Pointing alone cannot steady a stack that is shifting. Our guide to leaning chimney stacks goes through the causes and the risks.

Bricks that are breaking up

Where the faces of the bricks have flaked away, the joints have sunk deep, and a hand pushed lightly against the stack feels loose, the brickwork has lost the strength to take pointing. A few bad bricks can be cut out and replaced. When most of the top courses are in that state, replacing them one at a time costs more than starting those courses afresh.

Repairs that keep failing

If the same stack has been repointed and the damp is still coming back, the fault is probably deeper than the surface. Repeated callouts at a few hundred pounds each can add up to more than one proper rebuild, so a roofer who suggests a rebuild after a second repair is giving you sound advice, not an upsell.

Photographs taken at the survey show which of these cases applies to your stack, and the verdict is given before any figure.

A rebuild does not have to mean the entire chimney. The roofer takes the stack down only as far as the brickwork stays sound, and builds up from there.

The commonest job is a rebuild of the part above the roof, from the flashing line upwards. That is where wind, rain and frost do their worst, and it is where the failed brick usually sits. Taking it down course by course, and keeping the bricks that can be reused, gives a stack that looks like the old one with a fresh top.

Sometimes the damage runs lower, into the part of the stack inside the loft. Water that has run down a failed stack can soften the bricks below the roof line, and the roofer needs to see them from inside. That is one reason a survey includes the loft, not just a view from a ladder.

What decides how far down it goes

Three things settle the depth. The first is where the mortar stops being sound, which a hand tool shows quickly. The second is whether the stack is still attached to the house wall or party wall as it should be. The third is what is below: a chimney breast in a room, or an unused flue. If the whole stack from the loft floor upwards is affected, the job changes in scale, and the written quote reflects that.

Either way, the work is done from a scaffold or tower, not from a ladder, because a stack coming down in sections needs a platform to stand on and a safe place to put the bricks.

A rebuild runs in a set order, and each step protects the next.

Making safe and taking down

The scaffold goes up first, with boards and sheeting underneath to catch falling material. The pots and cowls are lifted off and set aside. If the cap and lead are in the way, they are lifted. The stack is then taken down course by course to the line the survey agreed. Each brick is checked, and sound ones are cleaned and stacked for reuse.

Building back up

The roofer lays the courses again in a mortar matched to the old brick, checking the line and the plumb at each stage, since a stack that leaves true by even a small amount at the base looks wrong at the top. Where the old bricks cannot be reused, matching bricks are sourced so the stack does not stand out on the street.

Finishing the top and the lead

New flaunching beds the pots and sheds the rain. The flashing is dressed into the fresh joints, in new lead if the old has gone, with the soakers and any back gutter fitted to suit. Pots are re-bedded, and a cowl or cap goes on any flue that is not in use.

Afterwards the roof, gutters and ground are cleared and all the waste goes with us, and the survey photographs let you compare the stack before and after. Our guide to the average cost to repair a chimney shows how the pieces of the work are priced.

A rebuilt stack is on show from the road, so it has to look like it belongs. That is easier on a house of the 1960s than on a Victorian terrace, and it matters most in the places where chimneys are part of the character of the street.

Arun District Council's conservation area guidance notes that chimneys are important features on the skyline of The Steyne and of Aldwick Road in Bognor Regis. On the Aldwick Road seafront it calls for restoring original roofing materials, and records that concrete interlocking tiles now sit where slate once did on many of the buildings. Stacks belong to the same picture: a taller stack with a clean crown, in brick that matches its neighbours, reads as right to the eye.

In practice, matching comes down to four checks. The first is brick: colour, size and texture. The second is the mortar colour and the joint profile. The third is the height and proportions, which should follow the old stack unless there is a reason to change them. The fourth is the pots, which are often reused or replaced with the same pattern.

Reclaimed brick can be a good match for older stacks, though it takes longer to find and costs more. A yard or a salvage dealer is the usual source, and the roofer should bring samples for you to look at beside the existing brick in daylight. For a later house, new brick of a close colour may serve. Where a stack is old enough to be listed or to sit in a conservation area, a close match is not just a matter of taste, because the council may ask for it. The guide to chimneys in conservation areas explains what that can mean for your home.

A like-for-like rebuild normally leaves the outside of the house looking the same, and under section 55 of the Town and Country Planning Act 1990, a job that leaves the exterior's appearance largely as it was falls outside the definition of development. That does not settle every case, so check these points first.

Listed buildings and conservation areas

Altering a listed building so that its special interest changes needs listed building consent, and taking down and rebuilding a stack can amount to that. In a conservation area the controls are tighter. Some councils have also made Article 4 directions that name chimneys: In parts of Old Portsmouth and Southsea, Portsmouth City Council's directions name chimney stacks as something that may not be taken down or changed without an application. Havant Borough Council's Langstone direction does the same for a stack that can be seen from the road. Ask the planning team of your own council before work starts.

Building Regulations

A rebuilt stack is part of the structure of the house. Whether a particular rebuild needs Building Regulations approval is a question for your building control body, which is either the council's team or a registered building control approver. We explain the route, and where a rebuild is notifiable we deal with the paperwork.

If you live in the South Downs National Park, the planning authority is the South Downs National Park Authority for some districts and the district council for others, while building control stays with the district. Ask which applies to your address, because the answer depends on the district. Our guide to chimney removal deals with the rules for taking a stack away altogether.

Because the work depends on how much of the stack must come down, no national guide gives a single figure for a rebuild, and we do not put one here. That figure is fixed in the written quote once we have surveyed the stack, and the main drivers are the height of the stack and the number of flues, the depth of the rebuild, the brick needed to match, and the access.

Access is the big one. Checkatrade's October 2026 scaffolding table puts a chimney scaffold at around £660 a week. If the scaffold takes up part of the footway, a highways licence is needed under section 169 of the Highways Act 1980 and the highway authority issues it: West Sussex County Council lists 10 working days' notice and £266 for a month, and Hampshire County Council lists ten clear working days and £211.90 for the first two weeks. Most national figures leave out VAT, which is 20 per cent, so check your quote states whether it is in.

A stack that is visibly leaning or has lost bricks is a safety question as well as a cost question. The Institution of Structural Engineers says dangerous structures can be reported to your local authority's building control team. Keep people and cars away from the area below, and have the stack looked at promptly.

After a storm, Which? says to tell your insurer promptly and keep the receipts for any emergency work. Photographs of the damage help too. Whether a claim is paid turns on the wording of the policy and the cause of the damage. Our guide on whether house insurance covers chimney repairs goes through the detail.