Flat Conversions Hammersmith

In Hammersmith, 77% of homes are already flats and 23% are houses, so a flat conversion starts from the smaller pool of W6 houses. The planning test is size. Local Plan Policy HO2 only allows a house to be split into two or more flats if its original net floor area is more than 120m2. We build conversions to the planning consent and the building regulations, and we also turn flats back into single houses.

In Hammersmith, 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 Hammersmith: 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.

Which Hammersmith houses can be split into flats

A Hammersmith house qualifies for conversion into flats only if, among the policy's tests, it is big enough and the scheme gives the right mix. Under Local Plan Policy HO2 the original house needs a net floor area above 120m2. At least 50% of the new flats must have two bedrooms or more, and the family sized homes need access to a garden or amenity space. Splitting a house into flats is also a material change of use, so planning permission is needed whatever the size.

In practice that points to the larger pre-1919 terraces and riverside period houses rather than a small two up, two down. The garden test means the garden normally goes with the family sized flat, often on the lower floors. Upper floors become the smaller flats, reached by a protected common stair. The owner or their designer applies for planning permission, and we price the build from the approved drawings, including the new front doors, meters and bin store the scheme shows.

Housing in Hammersmith

The Council Tax list puts Hammersmith at about 15,040 homes, 77% flats against 23% houses; 56% went up before 1919, 9% between the wars and 34% after 1945. Since most homes here are flats, a flat in Hammersmith can be split or combined only with the freeholder's consent, and changing the number of homes usually needs planning permission as well.

Space standards for a Hammersmith flat conversion

Every new flat in a Hammersmith conversion is measured against minimum space standards before it gets permission. Local Plan Policy HO11 brings floor area and room size standards, the Nationally Described Space Standards among them, to conversions and changes of use. London Plan Policy D6 sets minimums for all self-contained homes: 7.5 square metres and 2.15m wide for a single bedroom, and 11.5 square metres for a double. These are planning standards, not building regulations, so they are settled on the drawings before we price.

Ceiling height is where the top floors and rear additions of Victorian houses get caught. D6 wants at least 75 per cent of each flat's gross internal area to reach 2.5m floor to ceiling, and a low top floor or rear addition can pull a flat below that share. The policy also asks developments to maximise dual aspect homes and normally avoid single aspect ones. In a Hammersmith terrace that favours flats running front to back, and that often decides where the new stair goes.

Fire separation and sound testing between Hammersmith flats

Converting a Hammersmith house into flats is a material change of use, so building control applies Part B and Part E to the whole building, not just the new rooms. Under Part B, each flat becomes its own fire compartment: floors between flats are upgraded to the required fire resistance, the common stair is enclosed as a protected route, and each flat entrance gets a self-closing fire door. Detection and alarms follow the design, and every service hole through a separating floor is fire stopped.

Part E is where old timber floors struggle. For flats formed by a material change of use, Approved Document E asks walls, floors and stairs for at least 43 dB of airborne sound insulation, and floors and stairs for no more than 64 dB of impact sound. That usually means a new ceiling on independent joists or resilient bars below and a floating layer above. A pre-completion sound test then shows whether the Hammersmith flats meet the standard before building control signs off.

Meters, addresses, party walls and CIL on a Hammersmith conversion

Each new flat needs its own gas, electricity and water supply, or a clear arrangement for shared supplies, and the utilities want the new addresses before they fit meters. Street naming and numbering for the new flats is registered with the council, so apply early. Soil stacks and drainage for the extra kitchens and bathrooms are drawn so they stack between floors. In a Hammersmith terrace the meters often end up in a cupboard under the stair or in the front area.

Where the works cut into or build on a party wall, Hammersmith and Fulham Council strongly recommends following the Party Wall Act 1996 before starting. The building owner serves the notices, and we programme around the agreed awards. A conversion that creates a new dwelling can also be liable for the Community Infrastructure Levy in Hammersmith and Fulham, so the CIL paperwork should be in place with the council before work begins on site.

• Separating floors with independent ceilings and acoustic insulation
• Insulation to the walls, roof and floors the conversion touches
• Fire detection in every flat and the common hall, laid out to the fire strategy

VOA Council Tax stock of properties, March 2025, for Hammersmith Broadway, Brook Green, Ravenscourt Park North and Ravenscourt Park South. Counts rounded by the VOA.

People planning flat conversions in Hammersmith may also want structural alterations in Hammersmith, flat conversions across Hammersmith and Fulham, builders in London who take on conversions, refurbishing a flat that has already been converted, flat conversions across London and Central Heating Installation Cost.

The GS Renovation Difference in Hammersmith

A Hammersmith flat conversion has to satisfy the planning consent, the room size minimums and building control in one build, and the separating floors are where schemes usually slip. We price from the consented drawings after a survey, and set the programme around the fire stopping, sound insulation and inspection stages. You get one point of contact, and meters, fire doors and acoustic floors appear as priced items rather than surprises. Gas and electrical work is carried out and certified by registered specialists.

• Common parts, bin stores and cycle stores finished to the planning conditions
• Building control applications and inspections coordinated for you
• Mains-wired, interlinked smoke and heat alarms to the approved fire strategy

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.