Class ZA: demolishing and replacing detached buildings

Class ZA allows an eligible detached block of flats or former office, research or light industrial building to be demolished and replaced by one detached block of flats or house, subject to strict vacancy, size, site and prior approval rules.

This permitted development right applies in England under Part 20 of Schedule 2 to the GPDO. Check the qualifying building and land, the design limits and the written prior approval before committing to a scheme.

Which building qualifies?

Class ZA permits demolition of one purpose-built detached block of flats or one other detached building established for former B1(a) office, B1(b) research and development or B1(c) industrial use, including combinations of those uses, existing on 12th March 2020. These are the historic Use Classes Order categories, not permission for every use now in Class E. The replacement must be a single purpose-built detached block of flats or a single purpose-built detached C3 house.

The old building must have been built by 31st December 1989, have a footprint of no more than 1,000 square metres and a roof no higher than 18 metres excluding plant, masts and antennae. It must have been vacant for at least six months immediately before the prior approval application. The right cannot be gained by an interested person making the building unsafe or uninhabitable where repair or temporary support would be practicable.

What may be built?

The replacement must remain within the old building’s footprint. Its highway-facing external wall cannot come closer to the highway than the corresponding wall of the old building. The new building can have no more than the old number of storeys plus two. Its height, excluding plant, is limited to both 7 metres above the old building and 18 metres above ground level. Where additional storeys are provided, their internal floor-to-ceiling height cannot exceed the lower of 3 metres or the height of any old storey. Rooftop plant cannot exceed the old plant height measured as specified in ZA.1(m).

Class ZA permits the reasonably necessary demolition and construction operations, including a basement or cellar, services, safe access, fire escape and facilities within the new building. A new house built under Part 20 does not obtain the usual Part 1 householder rights.

Where the right is excluded

The old building and its curtilage cannot be article 2(3) land, a site of special scientific interest, a listed building or land within its curtilage, a scheduled monument or land within its curtilage, a safety hazard area, a military explosives storage area, or land within 3 kilometres of an aerodrome perimeter. Article 2(3) land includes conservation areas, National Parks, the Broads, areas of outstanding natural beauty (National Landscapes) and World Heritage Sites. Check any Article 4 Direction and conditions on earlier permissions as well.

An agricultural tenancy also blocks Class ZA unless both landlord and tenant expressly consent. The legislation additionally excludes relevant demolition of an unlisted building in a conservation area.

Prior approval issues

The authority considers transport and highways; contamination and flooding; design and appearance; natural light in every habitable room; amenity and neighbouring privacy and light; commercial noise; the effects of additional residents on nearby businesses; heritage and archaeology; demolition method; landscaping; and, where the development occupies previously unoccupied airspace, air traffic, defence assets and protected vistas. The detailed Class ZA application documents differ from the A to AD form: drawings must show both old and proposed building dimensions and elevations, window and room details, the number of old and new dwellings, plus a heritage and archaeology statement.

Before starting, provide an acceptable construction-management report covering demolition, working hours, noise, dust, vibration, traffic, materials, waste disposal and recycling. Carry out the work in accordance with it.

Every new home must meet the GPDO article 3(9A) minimum of 37 square metres gross internal area and the nationally described space standard. The development must be completed within three years from prior approval, and the local planning authority must be notified in writing of completion. The new dwellinghouses are subject to the statutory Class C3 use condition.

Application and decision

Apply for prior approval before work starts. Paragraph B sets out the application information, consultation and publicity procedure. The authority can refuse if eligibility is not demonstrated or if information is insufficient, and must refuse prior approval where adequate natural light is not provided in every habitable room of the proposed new dwellinghouses. Work must await a written notice granting prior approval; there is no automatic consent after 56 days. Approved plans and any reasonable conditions must be followed. Check the latest consolidated legislation before making a proposal.

Legislation and related guidance

Read the current Class ZA, ZA.1 and ZA.2 and the application rules in Paragraph B. Compare the other rights in the Part 20 eligibility table.

Class ZA legislation (checked 24th September 2026)

The following reproduces the consolidated Class ZA, ZA.1 and ZA.2 text as checked on 24th September 2026. Read the official Part 20 text for the legal source and any subsequent amendments. Contains public sector information licensed under the Open Government Licence v3.0.

Permitted Development

ZA.—(1) Development consisting of works for the demolition of one or other of—

(a) any building comprising a single purpose-built detached block of flats, and

(b) any other single detached building, comprising premises established—

(i) for office use falling within Class B1(a) of the Schedule to the 1987 Order,

(ii) for research and development falling within Class B1(b) of the Schedule to the 1987 Order, or

(iii) for an industrial process falling within Class B1(c) of the Schedule to the 1987 Order,

or for any combination of them,

existing on 12 March 2020, together with its replacement by a single building covered by sub-paragraph (2), involving operations listed in sub-paragraph (3).

(2) The building in question is to comprise one or other of—

(a) a purpose-built detached block of flats, or

(b) a purpose-built detached dwellinghouse.

(3) The operations in question are—

(a) operations reasonably necessary for the demolition and construction, which may include the installation of a basement or cellar in the new building, whether or not there is one in the old building;

(b) works for the removal of plant servicing the old building;

(c) works for the disconnection of services from the old building;

(d) works for the removal of any means of access to and egress from the old building;

(e) works for the removal of storage and waste from the old building;

(f) works for the installation of plant to service the new building;

(g) works for the installation of services to be connected to the new building;

(h) works to enable access to and egress from the new building, including means of escape from fire;

(i) works for the construction, within the new building, of storage, waste or other ancillary facilities to support the new building;

(j) the use of scaffolding and other temporary structures to support the operations listed in paragraphs (a) to (i) over a period—

(i) starting with their installation no earlier than one month before the beginning of those operations, and

(ii) ending with their removal no later than one month after the completion of those operations.

(4) In relation to Class ZA—

Development not permitted

ZA1. Development is not permitted by Class ZA—

(a) if land covered by, or within the curtilage of, the old building—

(i) is occupied in any part under an agricultural tenancy, unless the express consent of both the landlord and the tenant has been obtained;

(ii) is or forms part of article 2(3) land;

(iii) is or forms part of a site of special scientific interest;

(iv) is or forms part of a listed building or land within its curtilage;

(v) is or forms part of a scheduled monument or land within its curtilage;

(vi) is or forms part of a safety hazard area;

(vii) is or forms part of a military explosives storage area; or

(viii) is within 3 kilometres of the perimeter of an aerodrome;

(b) if the old building was constructed after 31 December 1989;

(c) if the footprint of the old building exceeds 1,000 square metres;

(d) if the height of the highest part of the roof of the old building above ground level (not including plant, radio masts and antennae) is greater than 18 metres at any point;

(e) unless the old building has been vacant for a period of at least 6 months immediately prior to the date of the application for prior approval;

(f) if the old building has been rendered unsafe or otherwise uninhabitable by the action or inaction of any person having an interest in the land on which the old building stands and it is practicable to secure safety or health by works of repair or works for affording temporary support (and for this purpose keeping the old building vacant does not of itself count as action or inaction);

(g) if the demolition is “relevant demolition” for the purposes of section 196D of the Act (demolition of an unlisted etc building in a conservation area);

(h) if any of the footprint of the new building falls outside the footprint of the old building;

(i) if any part of the exterior wall of the new building nearest to a highway is nearer to the highway than the part nearest the highway of the exterior wall nearest the highway of the old building;

(j) if the height (not including plant, radio masts and antennae) of the new building would at any point exceed the lower of—

(i) 7 metres above the height (not including plant) of old building; or

(ii) 18 metres,

above ground level;

(k) if the new building has more than X + 2 storeys, where “X” is the number of storeys in the old building;

(l) if the new building has more storeys than the old building and the floor to ceiling height of any additional storey in the new building, measured internally, would at any point be greater than the lower of—

(i) the floor to ceiling height, measured internally, of any storey in the old building; or

(ii) 3 metres; or

(m) if the height of any plant on the roof of the new building as measured from the lowest surface of that roof would be greater than the height of any existing plant as measured from the lowest surface of the existing roof on the principal part of the old building.

Conditions

ZA.2.—(1) Development under Class ZA is permitted subject to the following conditions.

(2) Where any development under Class ZA is proposed, development is permitted subject to the condition that before beginning the development, the developer must apply to the local planning authority for prior approval of the authority as to—

(a) transport and highways impacts of the development;

(b) contamination risks in relation to the new building;

(c) flooding risks in relation to the new building;

(d) the design of the new building;

(e) the external appearance of the new building;

(f) the provision of adequate natural light in all habitable rooms of each new dwellinghouse in or comprising the new building;

(g) the impact of the development on the amenity of the new building and of neighbouring premises, including overlooking, privacy and light;

(h) impacts of noise from any commercial premises on the intended occupiers of the new dwellinghouses;

(i) the impact on business and new residents of the development’s introduction of, or increase in, residential use in the area in which the development is to take place;

(j) the impact of the development on heritage and archaeology;

(k) the method of demolition of the old building;

(l) the plans for landscaping of the development, including the planting and maintenance of shrubs and trees; and

(m) any—

(i) air traffic and defence asset impacts of the development, and

(ii) impact that, because of the siting of the new building, the development will have on a protected vista identified in the Directions Relating to Protected Vistas dated 15 March 2012 by the Secretary of State,

unless no part of the new building (including plant, radio masts and antennae) occupies airspace not occupied by the old building (including plant, radio masts and antennae).

(3) In sub-paragraph (1)(h), “commercial premises” means any premises in the surrounding area which are normally used for the purpose of any commercial or industrial undertaking which existed on the date of the application under sub-paragraph (2), and includes premises licensed under the Licensing Act 2003 or any other place of public entertainment.

(4) When the developer applies under sub-paragraph (2), paragraph B (procedure for applications for prior approval under Part 20) applies to the application and the material covered by paragraph B(1A) to B(1C).

(5) Any development under Class ZA is permitted subject to the condition that it must be completed within a period of 3 years starting with the date prior approval is granted.

(6) Any development under Class ZA is permitted subject to the condition that before beginning the development, the developer must provide the local planning authority with a report for the management of the construction of the development, which is acceptable to the authority and sets out the method of demolition, the proposed development hours of operation and how any adverse impact of noise, dust and vibration and traffic on occupiers of the new building and adjoining owners or occupiers will be mitigated, the proposed use of materials, and the plans for the disposal and recycling of waste generated by the development and that in carrying out the development the developer must comply with the report.

(7) The developer must notify the local planning authority of the completion of the development as soon as reasonably practicable after completion.

(8) The notification referred to in sub-paragraph (6) must be in writing and must include—

(a) the name of the developer;

(b) the address or location of the development; and

(c) the date of completion.

(9) Any new dwellinghouse created under Class ZA is to remain in use as a dwellinghouse within the meaning of Class C3 of the Schedule to the 1987 Order and for no other purpose, except to the extent that the other purpose is ancillary to the primary use as a dwellinghouse.

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Page updated: 24th September 2026