New flats above shops under Part 20 permitted development

Building flats above shops permitted development is possible in England without a full planning application, through Part 20 of Schedule 2 to the General Permitted Development Order 2015. One point of terminology first, because it trips people up in pre-application emails. Class A of Part 20 covers upward extension of a detached block of flats. Commercial buildings with shops, cafes, offices or a launderette at ground floor are dealt with by Class AA for detached buildings and Class AB for buildings in a terrace. Those two are the ones that matter for a parade of shops.

Which buildings and uses qualify

The ground floor use has to be right. Classes AA and AB apply where the existing use falls within Class E of the Use Classes Order, or is a betting office, pay day loan shop or launderette, or is a mix of those uses with an existing dwellinghouse.

That covers most high street parades: shops, cafes, restaurants, professional services, clinics, nurseries, gyms and offices are all inside Class E since the 2020 changes. Pubs, hot food takeaways and most sui generis uses are outside it, which rules out a surprising number of buildings at the ends of parades.

Then check the site. The right does not apply on article 2(3) land, which means conservation areas, National Parks, National Landscapes, the Broads and World Heritage Sites. It does not apply to listed buildings or land within their curtilage, scheduled monuments, sites of special scientific interest, safety hazard areas or military explosives storage areas. In practice that removes most historic town centres from the route altogether.

Check for an Article 4 direction as well, because several authorities have made them over Part 20 in town centres where they want design control.

Construction date limits

The building must have been constructed between 1 July 1948 and 5 March 2018. Both ends of that window catch real buildings.

Pre-1948 buildings are excluded because the right was never intended for older structures with uncertain construction. That knocks out most Victorian and Edwardian parades, which is the single biggest limitation on the route in older towns. The 2018 cut-off prevents developers building low and then extending upwards straight away.

Evidence the date properly. Historic Ordnance Survey mapping, rating records, a building control completion certificate or a dated aerial photograph will do. An assertion in the covering letter will not, and the authority is entitled to refuse prior approval if the qualifying conditions are not demonstrated.

Storey and height restrictions

The permitted number of additional storeys depends on what is already there. Where the existing building has two or more storeys, up to two additional storeys are permitted. Where it has one storey, one additional storey is permitted.

Height is capped in more than one way:

1. The extended building must not exceed 18 metres in total height.
2. Each new storey must have a floor to ceiling height no greater than 3 metres, or no greater than the floor to ceiling height of an existing storey, whichever is less.
3. For a terrace building under Class AB, the extended building must not be more than 3.5 metres higher than the next tallest building in the terrace.

The third limit is the one that kills schemes on a stepped parade. A two-storey unit in the middle of a terrace of two-storey units gets very little, because there is no taller neighbour to measure against. Survey the whole terrace before designing anything.

The 18 metre cap has a second effect. It keeps most Part 20 schemes below the height threshold for higher-risk buildings under the Building Safety Act 2022, so Planning Gateway One usually does not apply. Check the storey count as well as the height, because the definition uses both.

Prior approval matters and the evidence needed

Prior approval is required for a defined list, and the list is long enough that the process feels like a planning application. It covers transport and highways impacts, air traffic and defence asset impacts, contamination risk, flooding risk, external appearance including design and architectural features, impact on the amenity of the existing building and neighbouring premises including overlooking, privacy and loss of light, whether adequate natural light will be provided in all habitable rooms of the new dwellings, and the impact of the introduction of residential use on the business uses in the area.

The determination period is eight weeks. Submit as though it were a full application: existing and proposed drawings, a structural appraisal, a daylight and sunlight assessment, a contamination screening note and a transport note.

Two of those matters deserve particular care. Adequate natural light in habitable rooms was added because early schemes produced poor flats, and a Daylight and Sunlight Assessment reporting against the current BRE guidance is the way to deal with it rather than asserting that windows are large. Contamination risk on a site with a former dry cleaner, petrol station or workshop below needs a Contaminated Land Assessment at least at desk study level, prepared by a suitably qualified person.

The new dwellings must also meet the nationally described space standard. That is a condition of the class rather than a prior approval matter, so failing it means the development is not permitted at all.

Access, refuse and cycle storage

This is where parades defeat the theory. Two new storeys of flats need a separate residential entrance, a stair or lift core, a bin store and cycle parking, all of which have to come out of the ground floor or the rear yard.

Taking the space from the shop reduces the retail unit, which the landlord may not accept and which affects the business impact assessment. Taking it from the rear yard removes the servicing area, which the highway authority will notice. Putting the entrance on the shopfront changes the external appearance, which is a prior approval matter.

Draw the ground floor before you draw the flats. Schemes are abandoned at this stage more often than at any other.

Refuse storage has to work for the collection authority, which usually means a bin store within a set drag distance of the highway with level access. Cycle storage needs to be covered and secure. Neither is optional in most authorities' standards, even under permitted development, because external appearance and amenity are prior approval matters that catch them.

Daylight to the new flats and to neighbours

Two directions of assessment, and both get asked about.

Outward: the new storeys sit above a commercial frontage, often on a narrow street, and the flats can be overlooked from opposite. Assess daylight and sunlight to the new units, and design the layout so habitable rooms face the better aspect.

Inward: adding two storeys to a parade affects the properties behind, particularly where rear gardens of terraced houses back onto the parade. Vertical sky component and annual probable sunlight hours for those neighbours will be tested, and a set-back to the rear elevation is the usual fix.

Where the existing building already extends upwards, the comparison with the domestic route is instructive: adding a storey to a house under Class AA of Part 1 has different limits and a different prior approval list, and confusing the two costs a wasted application.

Where the route fails on practicality

Structure first. A 1960s parade built for two storeys with shallow foundations and no provision for future loading may need underpinning or a transfer structure, and the cost of that can exceed the value of the flats. Get a structural appraisal before the prior approval application, not after.

Then services. Two additional storeys need drainage that the existing stack cannot always take, a new incoming electrical supply, and gas or heat pump provision with external plant that has to go somewhere visible.

Then tenants. Building two storeys over an occupied shop means scaffolding, noise, and a lease that may not permit it. Where the shop is extending at the same time, the interaction with the Part 7 limits for extending a shop needs checking, because the two rights are assessed separately.

Finally the levy. Development under permitted development rights can still be liable for the Community Infrastructure Levy, and a notice of chargeable development has to be submitted before work starts where no planning permission exists. Missing that step has cost developers surcharges on otherwise sound schemes.

PlanScope drafts the supporting statements for prior approval submissions, structured to UK planning policy, with the site facts it cannot verify flagged for you. Enter your postcode on PlanScope to see which reports your building is likely to need.

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