Planning permission to demolish and rebuild a house

To demolish and rebuild a house in England you normally need full planning permission for the replacement dwelling, and the local plan policy that governs it is usually written around volume or footprint rather than design. There is a permitted development route, Class ZA of Part 20 of the General Permitted Development Order, but its limits are tight enough that most self-builders end up applying anyway. The demolition itself is a separate question with its own notification, and in a conservation area it needs permission in its own right.

Three consents, three timetables, and a levy calculation that rewards you for applying while the old house is still in use. Worth sorting out in that order.

Replacement dwelling policy and the volume test

Almost every adopted local plan has a policy on replacement dwellings in the countryside, and most have one for built-up areas too. The usual mechanism is a cap on the increase in volume or floor area over the original dwelling, expressed as a percentage, with the baseline being the dwelling as first built rather than as extended.

That baseline catches people. A 1950s bungalow with two later extensions may already exceed the policy allowance, in which case the replacement is measured against the original footprint and the extensions count against you rather than for you. Check the planning history and the original approved drawings before you measure anything.

In the Green Belt the test is different and harder. The Framework's exceptions to inappropriate development include the replacement of a building in the same use and not materially larger than the one it replaces. "Materially larger" is not defined nationally, so the local plan or the development management policies supply the figure, and inspectors have taken volume, footprint, height and visual bulk into account rather than a single number. In a National Landscape or National Park, landscape and design policies carry additional weight and a modest increase can still be refused.

Outside those designations the question is usually character. A replacement that doubles the ridge height on a street of modest interwar houses will struggle regardless of the volume arithmetic, and that is the argument the Design and Access Statement has to win.

The Class ZA route and its hard limits

Class ZA permits the demolition of a single detached dwellinghouse, or a terrace building, or a building in a specified commercial use, and the construction of a new dwellinghouse in its place, subject to prior approval. It was added to Part 20 in 2020 and it is more restrictive than it first reads.

Read the current consolidated text of Class ZA before relying on any of the numbers, because Part 20 has been amended several times since 2020.

The prior approval matters cover transport and highways, contamination, flood risk, design and external appearance, the amenity of neighbouring premises including overlooking, privacy and loss of light, air traffic and defence safeguarding, protected views, and the method of demolition and construction. That is a long list for a route sold as a shortcut, and the vacancy condition means an occupied family home cannot use it without standing empty first.

Where Class ZA does work is on a redundant detached house on a generous plot outside any designation, where the owner wants to rebuild on the same footprint. Even then, a Lawful Development Certificate under section 192 of the Town and Country Planning Act 1990 is the only formal way to confirm that works are lawful, so a prior approval plus certificate approach is worth considering where a limit is arguable.

Prior notification of demolition

Demolition is a building operation and therefore development, but Part 11 of Schedule 2 grants permitted development rights for it with conditions attached. For most buildings the practical effect is that you must apply to the authority for prior approval of the method of demolition and the restoration of the site before work starts, and then carry out the work in accordance with what is approved. The application fee is small relative to the rest of the project and the determination period is short.

Two situations change the answer completely.

In a conservation area, demolition of a building is relevant demolition and needs planning permission in its own right. Carrying it out without permission is a criminal offence, not a matter to be regularised afterwards. The same principle applies to a listed building, where demolition needs listed building consent.

Where the building is unsafe and demolition is required under a notice served by the local authority under the Building Act 1984, different provisions apply. Do not assume that a structural engineer's letter is equivalent to a statutory notice.

Separately, the Construction (Design and Management) Regulations 2015 and asbestos duties under the Control of Asbestos Regulations 2012 apply to the works themselves. A refurbishment and demolition asbestos survey on a pre-2000 house is not optional.

Whether the existing dwelling is still lawful

The replacement dwelling policy only helps if there is a lawful dwelling to replace. Where a house has stood empty and derelict for years, the authority may argue the residential use has been abandoned, in which case the proposal is a new dwelling in that location and is assessed against policies on isolated homes in the countryside rather than replacement policy. That usually means refusal.

Abandonment turns on four factors drawn from the case law: the physical condition of the building, the length of the period of non-use, whether there has been any intervening use, and the evidence of the owner's intention. None is decisive alone. A sound house empty for five years with council tax paid and the roof maintained is a different case from a roofless shell colonised by scrub.

Build the evidence before you apply. Council tax or empty property records, utility accounts, insurance policies, dated photographs showing the roof and windows intact, and any correspondence showing an intention to return the building to use all help. Where the position is finely balanced, a certificate of lawful existing use under section 191 settles it before you spend money on design.

Biodiversity net gain on a replacement dwelling

This one surprises most self-builders. A demolition and rebuild is not a householder application, so the householder exemption from mandatory biodiversity net gain does not apply. Unless another exemption is available, the scheme needs a biodiversity gain plan showing a 10 per cent uplift secured for 30 years.

The exemptions worth checking are the de minimis threshold, which applies where the development does not affect onsite priority habitat and affects less than a small stated area of onsite habitat or a short length of linear habitat, and the self-build and custom housebuilding exemption, which has its own conditions on the number of dwellings and the site area. A rebuild on the same footprint inside an existing garden often falls within de minimis. A rebuild that takes in lawn, hedge and a few trees usually does not.

Where the regime bites, the Biodiversity Net Gain Assessment rests on the statutory metric, and the Environment Act 2021 regime expects that metric to be completed by a competent person with the gain plan approved by the authority. A draft is the starting point for that person, not a substitute for them. Bats are a separate and earlier problem: a house with a slate roof, soffit gaps or a loft used by nobody for a decade needs a bat survey before demolition, and the survey and any mitigation licence require a suitably licensed ecologist under the Wildlife and Countryside Act 1981 and the Conservation of Habitats and Species Regulations 2017.

Carbon, retrofit and the case for keeping the shell

Demolition throws away the carbon already embodied in the structure. Policy has started to notice. Some authorities now ask applicants to justify demolition against retention and retrofit, and in London the position is firmer, with whole life carbon reporting expected on larger schemes and a retrofit-first stance in the Mayor's guidance.

For a single house outside London a formal Whole Life Carbon Assessment is rarely a validation requirement, and councils expect a suitably qualified author where one is asked for, with professional review strongly advised. But a short paragraph in the planning statement explaining why retention was not practical, with reference to structural condition, floor-to-ceiling heights, thermal performance and the cost of achieving the target standard, costs nothing and heads off the question.

Honest uncertainty here: the direction of travel on demolition and embodied carbon is clear, and the point at which national policy makes it a formal test is not.

Levy liability and the existing floorspace offset

Community Infrastructure Levy liability is calculated on net additional floorspace, and the floorspace of a demolished building can be deducted where it was an in-use building. The test is lawful use for a continuous period of at least six months within the three years ending on the day planning permission first permits development.

The consequence for sequencing is blunt. Apply, obtain permission and get the liability calculated while the old house is still occupied, and the existing floor area comes off the charge. Demolish first, leave the site empty for a year and then apply, and the deduction may be lost and the whole of the new house becomes chargeable.

Self-build exemption is available for a dwelling built by or on behalf of an individual for their own occupation, subject to claiming it correctly before work starts and living in the property for three years. The paperwork is unforgiving about timing, so read the levy guidance rather than relying on a builder's recollection of it.

The evidence base for the application

For a straightforward replacement outside any designation, the pack is usually a site location plan, block plan, existing and proposed drawings including a volume comparison, a Planning Statement setting out the policy case, a design statement, a preliminary bat roost assessment, a tree survey where trees are affected, and drainage information. Add a flood risk assessment in Zone 2 or 3, a contaminated land desk study where the site has an industrial history, and the biodiversity gain plan where net gain applies.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. To see which of those documents your site is likely to need, enter your postcode on PlanScope.

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