Flat Conversions Bromley

Flat conversions in Bromley start from a house-heavy borough: 67% of homes are houses and 33% are flats, and 17% were built before 1919, when rooms and ceilings were often generous. The larger of those older houses are the stronger candidates for splitting into self-contained flats, while an interwar semi is a tighter fit. Bromley Local Plan Policy 9 permits converting a single dwelling into two or more units subject to criteria, and we build the conversion to the approved drawings: separating floors, fire protection, new services and a kitchen and bathroom for each flat.

In Bromley, converting a house into two or three flats is published at £50,000 to £120,000 including professional and council fees, and an England-wide guide puts a straightforward two-flat split at £40,000 to £80,000 in construction alone, which is the part a builder prices (indicative London ranges, Architectural Drawings and Mayfair Studio, 2026). GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Bromley: we build the conversion to the approved drawings, building control inspects the fire and sound separation, and a registered electrician certifies each flat's electrics.

What Bromley's Policy 9 asks of a house conversion

Bromley permits conversions but tests them. Local Plan Policy 9 Residential Conversions allows a single dwelling to become two or more self-contained or non-self-contained units subject to criteria on neighbour amenity, living standards, parking, character and housing choice. Bromley also says it will resist conversions that may cause a traffic hazard or harm residential amenity through noise, visual impact or other inconvenience, so bin stores, bikes and parking belong in the first drawings.

The ground floor has a preference attached. Policy 9 says that where ground floor accommodation is proposed in a conversion, preference is given to family housing units with direct access to a garden. On a Bromley house with a long back garden, that often means a larger ground floor flat with the garden and one or two smaller flats above. The layout decides where the new stair, meters and separate entrances go, so settle it before pricing.

Housing in Bromley

Roughly 143,450 dwellings sit on the valuation list for Bromley. 67% are houses and 33% flats, and by age 17% predate 1919, 30% are interwar and 53% post-war. 24% of homes here are semi-detached; the side of a semi in Bromley is where a separate entrance for the upper flat is most often placed.

Room sizes and ceiling heights for new Bromley flats

Each new flat in Bromley has to meet the London Plan space standards. Bromley's Local Plan says the Mayor's housing quality standards apply to new build, conversions and changes of use. London Plan Policy D6 sets a one-bedspace single bedroom at no less than 7.5 sq m and 2.15m wide, and a double or twin bedroom at no less than 11.5 sq m. The floor plan is drawn to those numbers before it is drawn to anything else.

Height is often the harder test in a converted house. Policy D6 sets a minimum floor to ceiling height of 2.5m for at least 75 per cent of the Gross Internal Area of each dwelling. A pre-1919 Bromley house often clears that on the lower floors, but new acoustic ceilings eat into it, and attic rooms can fail it. We check the finished heights against the build-up of each floor before the ceilings go up.

Sound and fire compartments between flats in a Bromley house

The floors between flats do the most work in a Bromley conversion. Approved Document E sets lower sound insulation performance for flats formed by material change of use: 43 dB airborne for walls and for floors and stairs, and 64 dB maximum impact for floors and stairs. Old timber joists will not meet that alone, so we add resilient bars, dense plasterboard and mineral wool, and float or overlay the floor above.

Part B treats each new flat as its own fire compartment. The floors and walls between flats are built to the fire resistance building control approves, and the flat entrance door becomes the compartment line onto the common stair, so it is a fire door fitted to that standard. In an older Bromley house the stair is usually the shared route out, so it is enclosed and lined to keep the compartments apart. Once the flats are occupied, the common parts have a responsible person under the fire safety order, usually the freeholder. A pre-completion sound test is required, so trial readings before the ceilings close are worth taking.

Upper floors over Bromley shops and the party wall

Not every Bromley conversion starts with a house. Local Plan Policy 97 permits converting upper floors of shops or commercial premises in town centres to residential use, subject to criteria. Policy 10 then asks an applicant who needs permission to convert a non-residential building to homes to show the premises are genuinely redundant. A storage floor above a town centre shop can therefore become a flat, but the evidence of redundancy goes in with the application.

Party walls arrive with the structural work. Bromley's party wall guidance says notice must be served at least two months before work to a party wall, or one month for excavation near adjoining buildings. That includes digging within 3 metres of a neighbour's building below its foundations. The building owner serves the notices, and we set the start date so the steel for a new opening or the new stair does not wait on an award that is still being agreed.

• A kitchen and shower room fitted in every new flat
• Bin stores, cycle stores and external works to the planning conditions
• Fire detection in every flat and the common hall, laid out to the fire strategy

VOA Council Tax stock of properties, March 2025, for all 39 statistical areas in Bromley. Counts rounded by the VOA.

Once you know the scope of the flat conversions in Bromley, it helps to read structural alterations in Bromley, our Bromley area guide, builders in London who take on conversions, party walls in a flat conversion, our London flat conversions page and House Rewire Cost.

Trusted Flat Conversions in Bromley

A conversion has more hand-offs than most jobs: building control, the fire strategy, sound testing, separate meters and utility connections, and new postal addresses for each flat. We run them as one programme and give you the sequence, so the stair enclosure, the separating floors and the service risers are built in the right order. The founder checks the drawings against the actual joists and ceiling heights before we price. You or your designer hold the planning consent; we build to it and supply the records for completion.

• Straight advice on what is and is not worth spending money on
• Mains-wired, interlinked smoke and heat alarms to the approved fire strategy
• Full plans application to building control, never a building notice

Checked by Abdelaaziz Saaid, founder and director of GS Renovation Ltd (Companies House no. 14611254). Structural design is by the consulting engineer appointed to your project.