Flat Conversions Wandsworth

Flat conversion in Wandsworth starts with policy, not with the stud walls. The Local Plan, adopted on 19 July 2023, protects the existing self-contained housing stock and limits turning single dwellings into flats through policies LP25 and LP26. Only 28% of the borough's homes are houses, so a house proposed for splitting is judged against rules written to keep family homes. We build self-contained conversions, and flats-back-to-house schemes, once the owner and their designer have the consent.

In Wandsworth, 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 Wandsworth: 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 Wandsworth planning policy allows when splitting a house

Splitting a Wandsworth house into self-contained flats is a material change of use that always needs planning permission, and the case has to fit policies LP25 and LP26. The candidates are the borough's houses: 23% of all homes are terraced and 5% semi-detached or detached. Household applications must also show that every home meets the housing standards in Policy LP27, including private internal space and daylight, so a dark lower room or a rear room facing a wall can sink a layout.

Small schemes carry a housing cost too. Under Policy LP23, developments of 1 to 9 dwellings (gross) must make a contribution towards affordable housing, subject to indexation, unless at least 15% of units are affordable on site. The London Plan counts residential conversions among the small-site forms of intensification where they add net housing. The owner's designer or planning consultant weighs all of this before a drawing is priced, and we build to the approved scheme.

Housing in Wandsworth

For Wandsworth the Council Tax list gives about 157,900 homes; by type 72% flats and 28% houses, by age 49% post-war, 7% interwar and 43% older than 1919. Since most homes here are flats, a flat in Wandsworth 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 that fix the layout of a Wandsworth flat

Every new Wandsworth flat, including one formed by conversion, must meet the London Plan minimum space standards. The London Plan table states that a new dwelling includes new build, conversions and change of use. Under Policy D6 a one-bedspace single bedroom must be at least 2.15m wide with a floor area of at least 7.5 square metres. A two-bedspace double or twin bedroom needs at least 11.5 square metres. Those widths decide where a new partition can land in a Wandsworth front room.

Height and outlook are often the harder tests. 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, and asks for dual aspect flats where possible. Where the borough sets no higher figure, it wants at least 5 square metres of private outdoor space for 1 to 2 people. The space standard is a planning test, not a building regulation, so it is settled at application stage.

Fire and sound separation between converted Wandsworth flats

A converted Wandsworth house has to stop fire and noise passing between flats that were once one home. Approved Document E sets the sound insulation performance for flats formed by material change of use at 43 dB airborne for walls, floors and stairs, and a maximum of 64 dB impact for floors and stairs. 43% of Wandsworth homes were built before 1919, and a house of that age has timber joist floors, often under a lath ceiling, so the separating construction is new work.

The floor between flats in a Wandsworth terrace usually needs a new resilient ceiling below, insulation between the joists and a deeper build-up above. Part B of the Building Regulations then asks for fire resistance between the flats, which the same layers help provide, and a protected way out, usually the common stair with fire doors to each flat. We sequence that work early and leave it open for building control, because the pre-completion sound test shows up a poor separating floor.

Services, addresses, neighbours and turning flats back

Each new flat needs its own supply and its own address. We plan separate electricity and gas meters, a water supply that can be isolated per flat, and new consumer units certified by a registered electrician. Each flat's boiler is fitted by a registered gas engineer, or electric heating or a heat pump goes in its place. The council's street naming and numbering team allocates the new flat addresses, which the utilities need before meters are fitted. Wandsworth Council is also the building control authority, and its completion certificate follows a satisfactory final inspection.

Where a conversion cuts into a party wall or builds on it, the Party Wall Act applies. Wandsworth's own page says party wall matters are between adjoining owners, and points owners to the government's explanatory booklet, so the building owner serves the notices before we start. The reverse job, joining flats back into one house, reduces the number of homes, and the Local Plan protects the self-contained stock, so the owner's designer should confirm whether permission is needed first.

• Fire stopping round every pipe and cable through a separating floor
• House to flat conversions into two or more self-contained units
• Decoration, flooring and making good throughout, ready to let or sell

VOA Council Tax stock of properties, March 2025, for all 38 statistical areas in Wandsworth. Counts rounded by the VOA.

Plenty of Wandsworth projects start with one job and grow, so it helps to see structural alterations in Wandsworth, our Wandsworth area guide, a building contractor for the whole conversion, the Party Wall Act when a conversion cuts a shared wall, our London flat conversions page and How to Choose a Builder.

Why Choose GS Renovation in Wandsworth

Conversions go wrong between the drawing and the inspection, so we build the separating floors, protected stair and service risers to the approved design and leave them open for checking. Our own trades run the strip-out, fire and sound work, new kitchens and bathrooms and the finishes. The owner's structural engineer designs any new beams, and a registered electrician certifies each flat's circuits. The planning application stays with the owner or their agent, and we supply the drawings, programme and records they need.

• One point of contact from first survey to handover
• Fire strategy for the stair and each flat entrance settled before strip-out
• Wet rooms stacked floor over floor to keep the drainage simple

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.