Can You Remove a Chimney Breast and Keep the Stack?

What the breast does for the stack

A chimney breast is the part inside the house that projects from the wall and carries the flue upwards. Above the roofline the same brickwork continues as the stack. The two are one structure, and the weight of the stack, with its pots, flaunching and any aerial, passes down through the breast, floor by floor, to the foundations or to a beam. Take out the breast in the upstairs rooms, and the part above has nothing underneath it. A stack that is a metre or two high and made of brick is heavy, so keeping it in place without support is dangerous.

That is why the usual conversation about removing a breast ends up at a question of support. Owners often want more floor space in a bedroom or living room, and keep the stack for its looks from the street or because the planning authority expects it to stay. Both aims are possible together, but the structure has to be arranged to suit.

The usual ways of supporting a stack

There are two main methods, and a structural engineer chooses between them after looking at the building.

Gallows brackets

A gallows bracket is a steel frame, shaped like the old gibbet it is named after, that is fixed to the wall and takes the weight of the brickwork above. It is a common solution when the lower breast is being taken out and the part above has to stay. The brackets are bolted into the structure and the remaining brickwork is built onto them. Bracket sizes and fixings depend on the weight and the wall they bear on.

Steel beams or a support at the roof

In some houses the stack is carried on steel beams spanning between supports, or on a structure framed into the roof timbers. This is more common where the breast is removed over a wider area or on more than one floor. The beam has to land on something that can take the load, usually a sound wall or a pad foundation. The roofer's part comes at the top, where the stack passes through the roof and the structure interacts with rafters and flashings.

Rules and approvals

This is structural work, and Approved Document A, which deals with structure, is the guidance building control uses to judge it. The usual route is to commission a structural engineer, who produces calculations and drawings, and then submit them to your building control body. That body may be the council's team or a private registered approver, and it inspects the work as it proceeds and issues a completion certificate. Do not rely on a builder's say-so. Without approval, a buyer's solicitor may raise questions when you sell. Rules on this kind of alteration are detailed, so take advice from the engineer and your building control body for your own case.

In terraced and semi-detached houses, the breast and stack are often shared with next door. Work to a shared structure can affect the neighbour's side. Talk to them early, and take advice about party wall matters. What a shared stack involves is set out under shared chimney stack repairs.

The order of work

1. A survey of the stack and breast, including the condition of the brickwork, the flues and the roof around them.
2. An engineer's design and building control application.
3. Temporary propping of the stack, or a plan for supporting it while the breast comes out.
4. Installation of the permanent support, whether brackets or beams, before the lower brickwork is removed.
5. Removal of the breast, making good the walls, floors and ceilings.
6. Checks on the stack above, with repointing, flaunching and flashings renewed as needed, since the stack is accessed anyway.

The best moment to look at the top of the stack is while the access is up. If the mortar is weak or a pot is cracked, it is cheaper to do it now than on a separate visit. Our guide to chimney repointing covers that work.

Is it worth keeping the stack?

Keeping the stack costs money, because of the support and the extra checks, and it leaves a part of the house that needs upkeep. It does preserve the roofline, and in conservation areas and on period streets the council may expect the stack to stay. If the stack serves no purpose and nobody minds its going, taking it down entirely can be simpler, which our page on chimney stack removal explains. We give a fixed written price for the roof and stack work on either route. Published UK guides give chimney repair from £500 up to £2,000, but breast removal and engineering sit outside those figures, and the price for yours follows the survey. See the chimney repairs hub for our other work.