Walkthrough: a shop converted to two flats above and below
An illustrative mixed use conversion, followed from the frontage policy through the space standards and the daylight and noise evidence to the conditions on the decision notice.
A shop with two floors above it, converted into two flats while the ground floor stays commercial, is one of the most common small mixed use schemes in England and one of the easiest to get wrong. This illustrative walkthrough follows a shop to flats conversion pack through a full planning application: what needed consent, what the space standards did to the layout, and which conditions came back on the decision notice. Every figure here is illustrative, invented for the walkthrough rather than taken from a real decision.
The building, the lawful use and the frontage policy
The illustrative building is a three-storey mid-terrace in a town centre, built around 1900, with a retail unit at ground floor, storage on the first floor used by the shop, and a self-contained flat on the second floor reached by a separate street door. The building sits in a conservation area and within a designated secondary shopping frontage in the adopted local plan.
The owner wanted two outcomes. Keep a smaller retail unit at the front of the ground floor, and create one new flat at the rear of the ground floor and one on the first floor, with the existing second-floor flat untouched.
The frontage policy decided the route. The local plan resisted the loss of retail floorspace in that designated frontage unless marketing evidence showed the unit was not viable, and it protected the active frontage at street level. Retaining the shopfront and a reduced retail unit answered the active frontage point. Losing roughly 40 per cent of the retail floorspace to a rear flat still needed justifying, so the planning statement carried a short marketing summary and a floorspace table showing retail retained against retail lost.
Which changes needed consent and which did not
Part 3 of Schedule 2 to the General Permitted Development Order 2015 contains several routes from commercial to residential, and each has been amended repeatedly. Class MA allows a change from Class E commercial, business and service use to dwellinghouses by prior approval, subject to the building having been vacant for three continuous months, a 1,500m² floorspace limit, two years of prior qualifying use, and a list of exclusions. Class G permits a change to a mixed use including up to two flats. Read the current text of the Order before relying on either, because the conditions have moved more than once.
None of the routes worked here. The ground floor retail unit was in active use, so the Class MA vacancy condition failed. The conservation area location brought in further restrictions. And the scheme involved physical works, a new rear door, altered fenestration and internal subdivision, that go beyond a change of use in any event.
So the application was a full planning application for change of use and alterations, with a separate check on whether listed building consent applied. It did not. Alterations to the shopfront in a conservation area did not need separate consent, but they did need to be drawn properly, because the conservation officer looks at the shopfront before anything else.
Space standards and the single aspect problem
The nationally described space standard sets a minimum gross internal area of 50m² for a one-bedroom, two-person dwelling on a single storey, with a minimum double bedroom of 11.5m² and built-in storage of 1.5m². The borough had adopted the standard through a local plan policy, which made it a policy requirement rather than guidance.
The first-floor flat came out at 58m² and worked. The ground-floor rear flat was the problem. At 44m² it fell short, and the only way to find the area was to take more from the retail unit, which pushed harder against the frontage policy. The resolution in this illustration was a one-bedroom, one-person flat at 39m², which the standard allows at a smaller area, with a single bedroom and a clearly drawn furniture layout.
Single aspect was the other constraint. Both new flats faced one direction. Single aspect north-facing accommodation attracts objection in many local plans, and these faced south, which helped. The design response was to pull the kitchen away from the window wall, keep the habitable rooms on the external elevation, and show the ventilation strategy on the plans.
Refuse, cycle storage and the shared entrance
This is where small conversions lose weeks. The council's own standards asked for 1.5 cycle spaces per flat and separate waste storage for the commercial and residential uses, with a drag distance from the storage point to the collection point of no more than a stated figure.
The pack included a waste strategy drawing showing a residential bin store in the rear yard, a separate commercial bin store, the bin sizes by waste stream, the collection route and the drag distance measured. The cycle store went in the same yard, covered and lockable, with the stand type named.
Three details drew officer comments: bins cannot be dragged through a habitable room, a shared residential and commercial bin store will usually be refused on management grounds, and a yard that is also the only means of escape cannot be filled with bins. Draw the yard once, with everything on it, and the problems become visible before the officer finds them.
Daylight into a rear ground-floor flat
A ground-floor rear flat in a terrace, with a boundary wall and a two-storey back addition nearby, is the hardest daylight case in a small conversion. The assessment followed the BRE guidance on site layout planning for daylight and sunlight, which in its current edition works from target illuminance in a proportion of the room rather than the older average daylight factor approach.
The Daylight and Sunlight Assessment tested the living and kitchen space and the bedroom, modelled the rear boundary wall and the neighbouring back addition, and reported the results room by room. The bedroom passed. The living space fell short against the target until the window was enlarged and the rear door glazed, at which point it met the target over just over half the floor area.
The honest position in the planning statement was that the living space met the target by a narrow margin and that enlarging the opening had been necessary to get there. Officers respond better to that than to a report that quietly omits the boundary wall.
Noise between the commercial and residential parts
A shop below two flats is a noise case whether or not the shop makes much noise. The council asked for an assessment of noise from the commercial unit and its plant on the intended occupiers, which is the standard requirement where new residential accommodation is created above or beside commercial premises.
The Noise Impact Assessment measured background levels in the yard and inside the first-floor rooms, assessed the existing refrigeration condenser against the BS 4142 method, and set out the internal levels sought by BS 8233 for living rooms and bedrooms. The mitigation was a floating floor over the retail ceiling, a resilient ceiling below, acoustic treatment of the stair enclosure, and relocation of the condenser to the rear wall at low level with a screen.
A related point. Where the commercial unit is a food use with extraction, the case changes completely and the odour and extraction evidence does more work than the acoustics, as a commercial extraction system and the odour objection shows.
The pack submitted and the conditions agreed
The application pack in this illustration ran to the application forms and ownership certificate, existing and proposed plans and elevations at 1:50 and 1:100, a site location plan, a planning statement covering the frontage policy and the housing standards, a heritage statement for the conservation area and shopfront works, the daylight assessment, the noise assessment, the waste and cycle strategy drawing, and a Phase 1 desk study because the site had a historic commercial use. Contamination is the item most often left out of a conversion pack, and a conversion where contamination was found mid build sets out what happens when it is.
The conditions on the illustrative decision notice covered sound insulation to be installed in accordance with the submitted scheme and verified by testing before occupation, the plant relocation and acoustic screen, the bin and cycle stores to be provided before first occupation, shopfront details to be approved, hours of construction, and a contaminated land condition requiring a watching brief during groundworks.
Scoping the full set of supporting documents at the start, rather than after a validation query, is what turns a six-month conversion application into a three-month one.
PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. Acoustic and contamination work on a scheme like this needs a suitably qualified author, and land contamination reporting is a role for a competent person under BS 10175. This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it.
Frequently asked questions
Can a shop be converted to flats under permitted development?
Sometimes, through Class MA or Class G of Part 3 of Schedule 2 to the General Permitted Development Order 2015, but the conditions are tight. Class MA needs three continuous months of vacancy, a floorspace limit of 1,500 square metres and two years of qualifying use, with exclusions for listed buildings and certain designated land. Physical alterations still need their own consent.
Do new flats created by conversion have to meet space standards?
Where the council has adopted the nationally described space standard through a local plan policy, yes. The standard sets 50 square metres as the minimum gross internal area for a one-bedroom, two-person home on one storey, with a smaller figure allowed for one-person accommodation. New dwellings created under Part 3 of the Order are also subject to the standard.
What waste and cycle provision will the council expect?
Separate storage for commercial and residential waste, sized by waste stream, within the drag distance the council publishes, and covered secure cycle parking at the rate in the local standards. Bins cannot be dragged through a habitable room, shared commercial and residential stores are usually refused on management grounds, and the store cannot block a means of escape.
Why does a rear ground-floor flat struggle on daylight?
Because the window faces a boundary wall or a neighbouring back addition, which blocks most of the visible sky. The current BRE guidance works from target illuminance across a proportion of the room, so a small window in an enclosed rear yard will usually fall short until the opening is enlarged or the room layout changes to put habitable space on the external wall.
Is a noise assessment needed for flats above a shop?
Normally yes, because new residential accommodation is being created beside an existing commercial use and its plant. The assessment measures background levels, tests any plant against the BS 4142 method and sets internal levels for living rooms and bedrooms, then specifies sound insulation and plant relocation or screening as mitigation.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.