The short answer
A shared chimney stack belongs to the houses it serves, so the repair is normally a conversation between neighbours before it is a job for a roofer. Check your title deeds for who is responsible, agree the work in writing, and split the cost fairly. Removing chimneys from a party wall brings in a party wall notice under GOV.UK guidance.
Why one stack serves two houses
Terraced and semi-detached houses were often built in pairs or rows, with fireplaces back to back on either side of a party wall. The flues from both houses rise together inside one stack, which stands astride the wall above the roof. From the street it looks like a single chimney with a pot or two for each side, and newer owners are sometimes surprised to learn that half of it is not theirs.
That arrangement saves bricks and keeps the roofline neat, but it creates a shared structure. A crack on your side may run through to your neighbour's, water entering one flue can soak the other, and a leaning stack threatens both roofs. Our guide to chimney flashing explains how the junction with each roof is sealed, and why a failure on one side can show on both.
Who is responsible?
There is no single rule. Responsibility depends on the title deeds, which sometimes say that the owners of the two houses share the cost of maintaining party structures, and sometimes say nothing. In many streets neighbours simply split the bill for a stack that serves both houses, on the grounds that each benefits from the repair.
Where a deed is silent, a sensible starting point is to ask what would happen to each house if the stack failed. If both would suffer, shared cost is usually fair. If the problem is clearly on one side, such as a loose pot over one flue, that owner may reasonably pay. We cannot give legal advice, so check your deeds, and ask a solicitor if the two of you disagree. A deed plan sometimes marks which wall is the party wall, and that settles more arguments than any opinion. If the plan is unclear, the Land Registry copy of your title is the next place to look, and a neighbour may hold a similar document that you can compare. The survey photographs help, because they show which flue and which section has failed.
Agreeing the work with your neighbour
Start with a friendly conversation and show the photographs. Pick a calm moment, not the day water comes through the ceiling, and offer to share the roofer's findings so nothing feels one-sided. Most neighbours want a leaking stack mended, since the damp reaches their ceiling too, and a joint repair saves each household paying for its own scaffolding. MyBuilder's scaffolding guide, updated in August 2026, gives £400 to £900 for chimney-height scaffolding, and splitting one scaffold is cheaper than erecting two.
Put what you agree in writing, even an email. Note what will be repaired, how the cost splits, who pays the roofer and when the work is due. If your neighbour is away or rents the house, the landlord or managing agent should be contacted. We can give each of you the same written quote, which keeps everyone working from one set of figures and one set of photographs.
Party walls and removing a shared chimney
Repairs to the top of a stack do not usually need a notice, but taking a chimney out is different. GOV.UK names the removal of chimneys from a party wall as work that needs a notice to your neighbour, served two months to a year ahead of the start date. They have 14 days to say yes in writing, and no reply cannot be read as a yes.
Removal inside the house brings Building Regulations as well. The Planning Portal states that removing chimney breasts always needs Building Regulations approval since they form part of the structure, and recommends a structural engineer. Our page on chimney waterproofing covers one treatment neighbours often disagree on, since coating one side only leaves the other exposed.
Timing and cost of a joint repair
A shared repair tends to take longer to organise than to do. The roofing itself is usually a day or two, but agreeing dates, arranging access across both roofs and waiting for scaffolding all take time. Our page on how long chimney repairs take gives a realistic idea of the sequence.
For cost, MyBuilder's chimney repair guide, updated in August 2026, gives a typical repoint at around £750, within a range of £500 to £2,000, and lists a semi with a central chimney at £900 to £1,500. Those are national figures. Your written quote comes after the survey, as one total, and we are happy to address it to both households.
Making the survey work for both homes
Tell us at the start that the stack is shared. We photograph both sides of the stack and each roof junction, including the back gutter if there is one, which our page on the chimney back gutter explains. Both owners then see the same evidence, which avoids arguments about what is wrong. It also helps if one household wants a bigger job than the other; the photographs show what is essential and what is optional, so each side can decide with the facts in front of them.
If only one flue is affected, the quote reflects that and nothing more. Our workmanship guarantee lasts 10 years and is written down, and we leave each roof tidy. If you would like to start the conversation, the chimney repairs hub is a good page to show your neighbour.