Chimney Breast Removal and The Party Wall etc Act 1996
There is a trend for people to open-up their residential properties and remove chimney breasts, which are no longer in use. This action then provides some much needed additional floorspace in the property. However, this work should not be taken lightly, as it may have both serious structural implications as well as legal issues. The Party Wall etc Act 1996 is current legislation which may be applicable in some cases, but not all. Even if the Act is not applicable in your situation, extreme care needs to be taken in planning the structural removal of chimney breasts to avoid problems later.
The key point here is how to remove the projecting chimney breast without upsetting the rest of the building structure. They provide structural support to masonry walls as well as providing flues, a fact that many have overlooked in the past. There may well be projecting chimney breasts on both sides of a wall or party wall, and the disturbance of one side of the wall may have structural implications on one or both sides.
The stability of the wall has to be considered if part of the chimney is to be disturbed or cutaway. One does not want to be in the position whereby the alteration has been carried out, but the wall is potentially unstable. A neighbouring property might well become at risk in some situations, and this needs to be avoided at all costs.
Cutting away into a party structure, whether a wall or floor, may trigger The Party Wall etc Act 1996, and the need for building owners to serve notices on adjoining owners. An experienced professional adviser can help with this aspect or pre-notification of intended works to neighbours.
The use of steel angled ‘gallows brackets’ is structurally acceptable, if only one side of the party wall is disturbed to remove a projecting breast. There are standard details available for this work, which Building Control will usually accept. The brackets rely on bolting securely to the remaining supporting masonry wall, often with epoxy resin fixings. As one has to drill into the wall, if it is a party structure then formal Party Wall notices will need to be served by the building owner, prior to the works commencing.
However, once the neighbouring property wishes to also remove the chimney on their side of the wall after the first works were done, then that work needs special consideration. This is because the wall could easily become unstable if a large mass of masonry is removed on both sides of the wall. The remaining heavy brickwork at a high level still has to be safely supported, by what is now, a slender, thinner, lower section of masonry wall below.
Without being alarmist, there have been cases of collapse of chimney stacks through the roof following alterations done, where insufficient design thought was applied before works commenced. This is rare, however, and can easily be avoided with effective pre-planning and applying competent, engineering structural advice.
Many old flues have had little maintenance over the years, and have suffered from ‘sulphate attack’ of the mortar between the bricks. This makes the chimney and flue potentially less stable, than if say, a modern flue liner had been installed, and good external maintenance provided. A close inspection of the brick pointing, flashings, brickwork, brick oversailing courses, pots and flaunching is advisable by the builder or a surveyor, of a safe scaffold, before any works start.
Coming back to the neighbouring owner, who wishes to carry out chimney removal on their side also, there is a safe solution available. This is more involved and costly than using ‘gallows brackets’, however. It involves the installation of steel beams/trimmer beams which support the remaining brickwork and bear into the party wall. The other end of the supporting steel beams would extend across to another load-bearing wall or structure across the room. A sketch drawing has been provided to show this.
The work entails cutting into the party structure, for supporting bearings or concrete padstones, so notices under The Party Wall etc Act 1996 would be required in advance of the work, and very possibly a Party Wall Award drawn up by one or two surveyors. The Party wall surveyors are not acting for ‘clients’ this time. They are acting impartially on protecting the interests of the building owner and the adjoining owner as regards the party wall, within the remit and limitations of the Act.
We must point out that the person who had previously done the chimney removal work, says Building Owner ‘A’, now becomes in this new situation, Adjoining Owner ‘A’, and it becomes the responsibility of his neighbouring owner to serve the necessary notices on him at the correct time. In the event both parties want to have the chimney breasts removed at the same time, they would, of course, both need to follow the Act, and ideally, appoint one single ‘Agreed’ surveyor to prepare the Party Wall Award.
In many cases, the structural arrangement may be simpler than shown, where one can span a new steel beam under and parallel with the remaining flue brickwork, and bear them onto the loadbearing front and intermediate walls via concrete pad stones.
This solution is sometimes seen in roof spaces and is an elegant structural solution, providing the existing walls can take the load and the overall steelwork span is not too great. The connection between the steel beam and the masonry needs to be effective and a semi-dry-pack cement-mortar can be used, well-rammed in, to ensure a good connection. Failure to do this well, can result in movement of the structural elements later on, and cracking of walls and finishes.
Any bolting into masonry should be carried out with resin-bolts as compared to cheaper expanding bolts, which can easily crack older brickwork. Resin-bolts should be tested with a hand-held bolt tester to establish they can carry the loads required, once set.
Building Control will need to be informed in the usual way before works commence and be provided with the necessary structural calculations from the engineer. Removal of bricks for insertion of concrete padstones is to be done with care. In some cases, in soft lime-mortar, the bricks can easily be lifted out by hand. In other cases, use of an angle grinder/disc-cutter may be required. Avoid excess vibration at all costs, and certainly no percussive tools.
Schedules of condition with adequate photographs before the works start can assist surveyors, engineers and clients in dispute situations, that may arise, later.
Finally, please be aware that the above information is for guidance only, and all necessary statutory, legal approvals, party structure approvals, and licences, must be first obtained before carrying out any structural works. The Construction (Design and Management) Regulations 2015 may also apply, even to residential domestic property, and has implications for Clients, Designers, and Contractors.
N.B. This blog was prepared on behalf of Arun Associates in conjunction with William J Marshall & Partners, to support a video on the subject matter.