Dangerous structures and emergency works in a conservation area

If a wall, chimney or roof becomes dangerous, the local authority can act under the Building Act 1984 without waiting for anyone's consent, and that emergency power does not cancel the need for listed building consent or planning permission for what follows. Those two things sit in different statutes administered by different parts of the council, and the gap between them is where owners of historic buildings get into trouble.

The short version. Make it safe, do the minimum, write to the conservation officer immediately, photograph everything, and keep what you take down.

What powers a council has over a dangerous structure

The Building Act 1984 gives the local authority, acting through building control, two routes.

Under section 77 the authority can apply to the magistrates' court for an order requiring the owner to carry out works to remove the danger, or to demolish the building or part of it. That is the route for a building that is dangerous but not about to fall down this afternoon.

Under section 78 the authority can take immediate action itself where it appears that immediate action should be taken to remove a danger, and recover the expenses from the owner afterwards. That is the emergency route. In practice it means the council's surveyor attends, decides what has to happen, and instructs a contractor to fence, shore, or take down the unstable element. Nobody waits for a planning application.

Section 79 covers a different problem, the building that is ruinous or dilapidated and seriously detrimental to the amenity of the neighbourhood, where the authority can require repair or demolition. In inner London the dangerous structures provisions of the London Building Acts apply instead, administered locally with a similar effect.

Two things follow for an owner. The council can act without your agreement and bill you. And an invoice for emergency works is not a defence to a later enforcement notice about the heritage consequences.

Emergency works and the consent position afterwards

Here is the division that matters. Removing a danger is one question. Altering, demolishing or rebuilding a designated heritage asset is another.

Works to a listed building that affect its character need listed building consent, and carrying them out without consent is a criminal offence. Demolition of an unlisted building in a conservation area, above certain thresholds, needs planning permission as relevant demolition, and carrying out unauthorised relevant demolition is also a criminal offence. Neither offence has an exception for "building control told me to".

What the legislation does provide is a narrow defence, which is a different thing from a consent. If the matter ends up being investigated, you have to be able to run that defence on the facts, and the facts are whatever your record shows.

So the correct sequence when something becomes dangerous on a listed building or in a conservation area is: secure the site, get a structural engineer out, do the least that removes the immediate danger, notify the local planning authority in writing at once, and then apply for consent for the permanent works. Not the other way round.

The defence for urgent works to a listed building

Section 9 of the Planning (Listed Buildings and Conservation Areas) Act 1990 contains the defence, and its conditions are cumulative. You need all of them, not most.

The works had to be urgently necessary in the interests of safety or health, or for the preservation of the building. It had to be impracticable to secure safety or health by works of repair, or by works for affording temporary support or shelter. The works had to be limited to the minimum measures immediately necessary. And written notice justifying the works in detail had to be given to the local planning authority as soon as reasonably practicable.

Read the second condition carefully, because it defeats most attempted defences. If the chimney could have been strapped, propped or scaffolded instead of taken down, demolition was not the minimum necessary. Temporary support is almost always practicable on a domestic building, which is why conservation officers react badly to a demolished gable and a letter arriving a fortnight later.

The fourth condition is the one people forget entirely. The notice has to be written, has to be addressed to the planning authority rather than to building control, and has to justify the works in detail. A verbal conversation with a building control surveyor is not notice to the local planning authority.

Where a danger develops over a weekend, send the email on the Monday with photographs attached. That email is worth more than any amount of later explanation.

Recording before anything is taken down

The record is the single most valuable thing you can create in the hour before the contractor arrives, and it costs nothing but attention.

What to capture:

• Wide photographs of each elevation from several positions, with something in frame for scale.
• Close photographs of the failing element and of the specific defect, taken before any disturbance.
• Photographs of the junctions where the element meets sound fabric, which is the evidence of how it was built.
• Measurements of the element: height, width, thickness, course heights, projection of mouldings or corbelling.
• A note of the materials: brick type and bond, mortar, stone, timber sizes and jointing.
• A dated sequence showing the works in progress, as well as before and after.

Where the building is of real interest, a historic building recording to an appropriate level is the proper version of this, and councils usually expect a suitably qualified author with professional review strongly advised. In an emergency you will not have that in place, which is exactly why the owner's own photographic record matters so much.

Set aside and label what comes down. Salvaged brick, stone, tile, slate, timber and ironwork from the building itself is the material a conservation officer will expect to see reused in the rebuild. Skipping it converts a defensible emergency into an avoidable loss, and the demolition contractor will not keep it unless instructed in writing.

Asbestos and other hazards need handling properly even in an emergency, and the survey position is covered in demolition, asbestos surveys and the planning submission.

Urgent works notices and repairs notices

The powers run in the other direction too, and owners of neglected historic buildings should know about them.

Under section 54 of the Planning (Listed Buildings and Conservation Areas) Act 1990 the local authority can execute works urgently necessary for the preservation of a listed building, and recover the cost from the owner. The power applies to unoccupied buildings, or to the unoccupied part of a building in use, and it is used for roof coverings, temporary propping, weatherproofing and making secure against entry. It can be extended to unlisted buildings in a conservation area where the preservation of the building is held to be important.

Section 48 allows a repairs notice, specifying the works reasonably necessary for proper preservation, which is the step that can lead to compulsory purchase where an owner does not comply.

These are not emergency powers in the Building Act sense. They exist because deliberate neglect used to be a reliable route to demolition, and the point of them is to close that route. An owner who allows a listed building to decay towards a dangerous condition should expect the authority to treat the decay as relevant history when the application for demolition eventually arrives.

What reinstatement will be expected

Assume reinstatement, and assume it will be close.

For a chimney stack, gable or parapet taken down in an emergency, the expectation is rebuilding to the original profile using the salvaged material, with the same bond, the same mortar specification and the same detail. Photographs and measurements taken before demolition are what make that possible, which is the practical reason for the record rather than the bureaucratic one.

Where the element cannot be rebuilt exactly, the application needs to explain why, with evidence, and the heritage statement is where that explanation sits. A lime mortar matched to the original, bricks salvaged from the same building, and a profile taken from the pre-demolition measurements is a proposal a conservation officer can support. New machine-made brick in cement mortar to a simplified profile is a proposal that attracts an objection and sometimes an enforcement notice requiring the work to be redone.

A structural survey of the retained fabric is usually needed alongside, both to establish what else is at risk and to show the authority that the rest of the building has been assessed rather than left to fail next winter.

The evidence to keep

Keep a single file with the engineer's report and its date, your photographic record, the measurements, the written notice to the local planning authority with proof of sending, any instruction to building control or correspondence from them, the demolition contractor's instruction showing the scope limited to the minimum, the salvaged materials inventory and the invoices.

If the works are ever questioned, that file is the case. Without it, an owner acting entirely reasonably can end up unable to show it.

This is general guidance, not legal advice. Where a listed building or a building in a conservation area becomes dangerous, take advice from a structural engineer and from the local planning authority's conservation officer immediately, and remember that unauthorised works to a listed building and unauthorised relevant demolition in a conservation area are criminal offences.

To see which structural and heritage documents a repair or rebuilding project is likely to need, enter your postcode on PlanScope and work through the guided questions. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.