The short answer
Removing all or part of a chimney breast is structural work that needs Building Regulations approval, so involve building control before it starts. Building control means B&NES Building Control or a registered building control approver. A structural engineer normally sizes the support that replaces the breast, and a stack shared with a neighbour adds party wall questions. Confirm the exact requirements with your building control body, because they depend on the building.
Why removal is more than knocking something down
A chimney breast is a thick mass of masonry. In many houses it does real work: it carries the weight of the breast above it, it can brace the wall it stands against, and in a terrace it may take part of the load from floors and from the roof. Taking it out, in whole or in part, takes away that support.
The stack above the roof is a separate matter. It sits on the breast and weighs on the roof structure around it. Removing the stack leaves a hole in the roof, which has to be closed properly with timber and a weathertight covering. Removing the breast below leaves whatever sat on it unsupported.
That is why removal falls under the heading of structural alteration. The regulations are there to make sure the building stays safe once the masonry has gone, and to get the work checked by someone independent of the builder.
Who to ask: your building control body
In England you have two routes for building control. One is the local authority, which in Bath means B&NES Building Control. Its address is Lewis House, Manvers Street, Bath BA1 1JG, its telephone number is 01225 477517 and its email is building_control@bathnes.gov.uk. The other is a private firm registered as a registered building control approver, a regime that replaced approved inspectors from April 2024.
The Planning Portal says approval always applies when chimney breasts are removed, because they are part of the structure. Taking down only the stack above the roof may not need it, so check. Either body can tell you what it needs for a chimney removal, whether that is a building notice or a full plans application, and what it will inspect. Requirements differ between buildings, so ask the body that will sign the work off, not a friend who has done a similar job.
We explain consent and handle the Building Regulations side where work is notifiable. For a breast removal that involves the structure of the house, though, you will usually want your own structural engineer as well, and your building control body will often ask for their calculations.
What a structural engineer works out
When a breast is removed from a room, the load it carried has to go somewhere. The usual answer is a steel beam or a pair of supports that take the weight of the breast above and carry it to the walls on either side. The engineer calculates the size of the beam, the bearing it needs at each end, and the foundations or padstones that will take the load without cracking.
Temporary support during the work matters as much as the final design. Props and needles hold the masonry above while the breast below is taken out and the beam installed. This is not a task for improvisation, and an engineer's drawing lets the builder and the inspector work to the same details.
The engineer will also look at the wall alongside. A breast on a gable end may brace that gable against wind, and taking it out can leave the wall less stable. Where the stack above is staying, they will look at what supports it once the breast beneath has gone. Gallows brackets, a type of steel support that carries the stack on the wall, are one way of holding a stack over a space where the breast has been removed.
Party walls and shared stacks
Many Bath houses are terraced or semi-detached, and chimney breasts often sit on the party wall between two homes. A shared breast or a shared stack belongs, in practice, to both properties, and work to it affects your neighbour.
Tell the neighbour before you start. Share the plans, explain the timing and the scaffold, and ask whether they plan work of their own. A shared stack is a common source of friction, because a leak or a collapse on one side hits both. Cutting away a chimney breast that projects from a party wall is work the Party Wall etc. Act 1996 names, so notice to the neighbour is normally needed before it starts. A party wall surveyor can say what applies to your case, since building control does not deal with party wall matters.
Our answer on chimney stack removal covers how the stack itself comes down when the neighbour's side stays in place, and the planning side of removal deals with listed buildings and conservation areas, which are a separate question from Building Regulations.
Dealing with the flue and the roof afterwards
If only the stack is coming down and the breast stays, the flue below needs treating. A flue left open at the roof collects rain; one sealed completely can trap damp and condensation inside the breast. The usual approach is to cap the flue and ventilate it, so that air passes through and the breast stays dry.
Where the breast is also removed, the flue goes with it, but any other flues sharing the stack must remain working. That is often the reason for keeping part of a stack: a neighbour's flue, or a boiler flue, passes through the same masonry.
The roof must be made good where the stack stood. That means trimming the rafters, fitting a proper junction at any adjoining wall, and finishing the covering to match the rest, slate matched to slate and tile to tile. We restore the roof to its original build rather than patch it. Gas appliances and solid fuel appliances have their own flue rules, so if any appliance connects to a flue in the stack, check with the installer before it is touched.
Weighing the cost and the paperwork
The costs behind a removal are not just the labour. They include the engineer's fee, the building control charge, the steel and padstones, the scaffold, the making good inside the rooms and the decorating. For the stack alone, MyBuilder's guide to chimney repair gives a typical UK range of £2,000 to £10,000 or more for a rebuild, which is a useful comparison when you are weighing removal against a rebuild. Your fixed quote follows the survey.
Keep the paperwork when the job is done. A completion certificate from building control is what a buyer's solicitor will ask for if you sell, and without it a removed breast can hold up a sale.
Insurance matters too. Some policies treat structural alteration differently, so tell your insurer before the work begins. Our page on chimney repair insurance explains what is typically covered and what is treated as maintenance. Other stack questions sit under chimney repairs.
