Class ZA: demolition and rebuild of a single dwellinghouse

Class ZA of Part 20 of Schedule 2 to the General Permitted Development Order 2015 lets you demolish a single detached house or a single detached block of flats and build a replacement in its place, subject to prior approval and a set of hard limits. The headline tests for class ZA demolish and rebuild are these: the old building was constructed before 1 January 1990, it has been vacant for at least six months, its footprint is no more than 1,000 m², and the new building sits within that footprint and rises no more than seven metres above the old, capped at 18 metres overall.

It is a narrow right and it is used far less than the publicity around it suggested. Where it does fit, it is quicker and more certain than a full application, because the matters the council can consider are listed.

What Class ZA permits and the building types covered

The right covers two building types and no others: a single detached building in use as a dwellinghouse, and a single detached block of flats. Terraced and semi-detached properties are outside it. So are houses in multiple occupation, commercial buildings, agricultural buildings and anything that is not detached on all sides.

The replacement must be a single dwellinghouse or a single block of flats. You cannot demolish one house and build two, and you cannot change the building type in either direction, so a block of flats cannot be replaced by a house. The new building must be used only as a dwelling or dwellings, and construction has to be completed within three years of the date of prior approval.

Demolition and rebuild under this class is a single operation. You cannot demolish under one route and then apply to build later, because the permitted development right attaches to the combined works.

Footprint, height and volume constraints

The dimensional tests are where most sites fail, and they are worth measuring before anything else.

Read the footprint test strictly. Within the footprint means the new building must sit inside the outline of the old one, so you cannot shuffle the plan sideways to improve the garden or square up a wonky Victorian plan form. A single-storey rear addition on the old house counts as part of its footprint, which sometimes helps, and an outbuilding separated from the house does not.

Height is measured from the same ground level for both buildings. On a sloping plot that calculation needs a surveyed section rather than a scale rule across an old drawing.

The vacancy and use requirements

The building must have been vacant for at least six months immediately before the date of the prior approval application. Vacant means unoccupied, and the evidence councils accept is the ordinary evidence of a dormant property: council tax records showing an empty property discount or premium, closed utility accounts with no consumption, and photographs over the period.

This requirement catches owner-occupiers who want to replace the house they live in. Moving out for six months before applying is the only way through it, and the six months has to be complete before the application goes in rather than before demolition starts.

The pre-1990 construction date needs evidence too. Historic mapping, a council tax banding record, a building control record or an estate agent's historic particulars all help. Where a house was substantially rebuilt after 1990 on older foundations, expect the council to query which building you are relying on.

The prior approval matters the council assesses

This is the part that gives the route its value, because the council's discretion is bounded. The matters for prior approval under Class ZA include transport and highways impacts, contamination risk, flood risk, the design and external appearance of the new building including its dimensions, the provision of adequate natural light in all habitable rooms, the impact on the amenity of neighbouring premises and of the new building itself, the method of demolition, and landscaping. In London and near aerodromes and defence assets there are further matters.

Design is in the list, which surprises people who assume prior approval means a free hand. The council can require a different external appearance, and on a prominent plot it will. Submit elevations, materials and a street context drawing as though it were a full application.

Natural light in habitable rooms is the sleeper issue. A deep plan replacement with rooms lit only by rooflights, or a basement bedroom with a lightwell, can be refused on that ground alone. Daylight calculations for habitable rooms are low-cost insurance on a tight plot.

Demolition method and construction management

The method of demolition is expressly a prior approval matter, which is unusual, and it is there because the right permits demolition next to buildings that remain occupied.

Submit a demolition method statement covering sequence, plant, dust suppression, asbestos survey and removal, protection of adjoining structures, hours of work and the route for removal of material. A Construction Management Plan covering wheel washing, deliveries and site hoarding usually goes with it. Where party structures or shared boundary walls are involved, the Party Wall etc. Act 1996 runs separately from planning and is not discharged by the prior approval.

Asbestos is worth flagging early. A building constructed before 1990 is very likely to contain it, and a refurbishment and demolition survey under the Control of Asbestos Regulations 2012 has to be done before work starts whatever the planning position says.

Excluded land and designated areas

Class ZA does not apply on Article 2(3) land, which means conservation areas, National Parks, National Landscapes and the Broads, nor on a World Heritage Site. It does not apply to a listed building or a building within the curtilage of a listed building, nor to a scheduled monument or land within its curtilage. Sites of special scientific interest, safety hazard areas and military explosives storage areas are also excluded.

If a conservation area boundary runs along your road, check which side the house is on before spending money. The exclusions are absolute rather than matters for the council's judgement, and the right either exists or it does not. The same binary logic applies to other householder classes, which is why side extensions under Class A in a conservation area behave so differently from the same works elsewhere, and why permitted development rights on a converted dwelling need checking rather than assuming.

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. Prior approval under Class ZA is not the same thing, and if there is any doubt about whether the right applies at all, an application for a certificate alongside the prior approval application is money well spent.

Comparing the route with a full application

Class ZA buys certainty on principle and speed. A full planning application buys flexibility.

Choose Class ZA where the existing footprint is the footprint you want, the plot is unconstrained, and the gain is simply a better building in the same position. Choose a full application where you want more floorspace than the old footprint allows, a different position on the plot, more than one dwelling, or any change of building type. A full application also lets you argue design on the merits rather than against a list of prescribed matters, which helps on a sensitive street and hurts on an ordinary one.

The cost comparison is less clear-cut than it looks. The evidence pack for a Class ZA prior approval, with vacancy evidence, construction date evidence, surveyed sections, daylight calculations and a demolition method statement, is not a thin document. A Planning Statement that walks the council through each qualifying test in order, with the evidence cited for each, is what turns a borderline case into an approval.

And there is one commercial point worth weighing. A replacement dwelling built under Class ZA is still a new dwelling for levy purposes, so the Community Infrastructure Levy position and any self-build exemption claim have to be handled in the usual way, with the notice of chargeable development that permitted development schemes require.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. Enter your postcode on PlanScope to see which reports a demolition and rebuild is likely to need. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.