Class ZA demolition and rebuild: the route nobody uses

Class ZA permits the demolition of certain vacant buildings and their replacement with homes, through prior approval rather than a planning application. On paper it is the boldest permitted development right in the Order. In practice hardly anyone uses it, and the reasons are worth understanding before you spend money finding out for yourself.

The right sits in Schedule 2, Part 20 of the Town and Country Planning (General Permitted Development) (England) Order 2015. It has been in force since 2020 and the constraints have not loosened.

What Class ZA permits and on what buildings

The right applies to a single detached building that was either a purpose-built block of flats or was last used for offices, research and development, or light industrial purposes. The replacement must be a detached building used as dwellinghouses or as a single dwellinghouse.

Three qualifying facts about the existing building do most of the filtering:

• It must have been constructed before 1 January 1990.
• Its footprint must not exceed 1,000 m².
• It must have been vacant for a continuous period of at least six months before the prior approval application.

The vacancy requirement alone removes most candidate buildings. A landlord with a tenanted office block cannot use Class ZA without first emptying the building and holding it empty, at a cost, with no certainty of approval at the end.

The right is not available on land within a conservation area, a National Park, a National Landscape, a World Heritage Site or the Broads, nor on sites of special scientific interest, listed buildings, scheduled monuments or land in their curtilage. Safety hazard areas and military explosives storage areas are also excluded.

Age, footprint and height constraints

The replacement building is tightly constrained by the one it replaces.

The footprint restriction is the commercial problem. A 1970s office block with a small floorplate and generous surrounding land cannot use that land, because the new building has to sit within the old footprint. Everything that would make the site work, a larger floorplate, a courtyard block, a second building, is outside the right.

The height allowance sounds generous until you apply it. Seven metres is roughly two residential storeys, and the 18 metre ceiling caps the total in any event, which also keeps the building below the threshold where the higher-risk building regime bites.

The prior approval matters the council considers

Class ZA carries the longest list of prior approval matters in the Order. The council can consider transport and highways impacts, contamination risks, flooding risks, the design and external appearance of the new building, the impact on the amenity of the new building and of neighbouring premises including overlooking, privacy and loss of light, the provision of natural light in habitable rooms, the impact of noise from commercial premises on future residents, the impact on heritage and archaeology, the method of demolition, landscaping, and, in relevant locations, air traffic and defence assets and protected views.

That is close to the range of issues a full planning application raises. The difference is that the council cannot refuse on principle, on housing mix, on affordable housing policy or on general local plan grounds.

Two further procedural points. Prior approval must be obtained before demolition begins, so the demolition method statement is part of the application rather than an afterthought. And a Construction Management Plan covering demolition sequencing, dust, noise, hours and vehicle routing does a lot of work in answering the method and amenity questions at once.

Why so few schemes use the route

Add the constraints together and the reason becomes obvious.

The building has to be pre-1990, detached, under 1,000 m² of footprint, and empty for six months. The replacement cannot be bigger in footprint, cannot be more than seven metres taller, and cannot exceed 18 metres. The prior approval process asks nearly as many questions as a planning application. And the outcome is a building constrained to the shape of a structure designed for a different use in a different era.

There are real advantages, and they are worth stating fairly. Affordable housing policy does not apply through the prior approval process, which on a scheme of any size is a material saving. The determination period is fixed. And the council's grounds for refusal are limited, which reduces the risk of a policy objection to the principle of residential use on an employment site.

The Community Infrastructure Levy still applies where the authority has a charging schedule, and the demolished floorspace may attract relief depending on the lawful use and occupation history, so check the CIL position before assuming a saving.

Comparison with a full planning application

For most sites, the honest comparison looks like this. Class ZA gives you certainty on the principle and a capped timetable, in exchange for a building shaped by the old footprint. A full application gives you the site, in exchange for policy risk, affordable housing and a longer programme.

Where the existing footprint already fills the developable area, Class ZA can be the better route. Where the site has slack in it, the right leaves value on the table.

A middle path is worth considering. Establishing eligibility under Class ZA, even without using it, creates a fallback position that carries weight in the planning balance for a full application, since a lawful alternative that could be built without permission is a material consideration. That argument has to be evidenced properly in the Planning Statement rather than asserted, and it works only where the fallback is genuine and reasonably likely to be implemented.

Evidence needed to establish eligibility

An application stands or falls on the qualifying facts, so evidence them properly.

1. Construction date before 1 January 1990: historic mapping, building control records, rating records or dated aerial imagery.
2. Last lawful use: leases, rating records, planning history and, where the use is contested, a lawful development certificate.
3. Six months of vacancy: business rates records showing empty property relief, utility accounts, marketing particulars and dated photographs.
4. Footprint under 1,000 m²: a measured survey rather than a scaled estimate from a plan.
5. Existing height: a survey with a stated datum, since the seven metre allowance is measured from it.
6. Detached status and site boundaries: a site plan showing separation from adjoining buildings.

Site condition evidence follows: a contamination desk study, flood risk information, a highways and access appraisal, a daylight assessment for the new habitable rooms, and a noise assessment where neighbouring commercial premises could affect future residents. On an industrial estate, that last one is often the deciding issue, and a Transport Statement is worth preparing alongside it because access arrangements designed for a light industrial use rarely suit residents.

Where the evidence on age, use or vacancy is thin, resolve it before applying. A prior approval refused on eligibility is a wasted 56 days and a signal to the council that the building is being watched.

Browse the 66 report types by category to build the evidence list for a Class ZA application, then check it against the council's published requirements.

This is general guidance, not legal advice. A Lawful Development Certificate is the only formal way to confirm that works are lawful, so check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.