Flat Conversions Soho

Flat conversion work in Soho starts from a building stock that is already mostly flats: the VOA counts 98% of homes across Fitzrovia West and Soho as flats and 2% as houses. Splitting a family house is therefore rare. New self-contained flats here tend to come from reworking an upper floor, dividing a large flat, or changing commercial space to homes with planning permission. We build the separating floors and walls, fire protection, services and finishes to the consented drawings and hand over flats ready for building control sign off.

In Soho, 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 Soho: 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.

Where new self-contained flats come from in Soho

In Soho the house into flats conversion that fills suburban planning files barely exists. The VOA puts 2% of homes in its Fitzrovia West and Soho area in terraced houses and none in semis or detached houses, so the raw material for a conversion is more often an upper floor, a large flat or commercial space. Whatever the starting point, turning it into more than one home is a material change of use and needs planning permission and building regulations approval. If the building is listed, listed building consent is needed as well for the works inside and out, though it has no bearing on the use class.

Commercial floors have no shortcut. As modified by the Secretary of State, Westminster's Article 4 Direction on Class E to C3 rights in the Central Activities Zone covers the Soho Special Policy Area, and it was made on 14 July 2021. A Soho owner wanting flats in commercial floors above a shop therefore makes a full planning application; where the upper floor is already a flat, splitting it into more flats needs one too. Either way it is judged against the City Plan, and the design has to prove it meets the space standards before any building work is priced.

Housing in Soho

By the valuation list's count, the Fitzrovia West & Soho statistical area holds about 6,840 homes, 2% houses and 98% flats; by age, 48% were built before 1919, 5% between the wars and 47% since 1945. Since most homes here are flats, a flat in Soho 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 a new Soho flat has to meet

Where a Soho building gains new self-contained flats, London Plan Policy D6 sets minimum internal space standards whatever the tenure, and the London Plan counts conversions and change of use as new dwellings. Policy D6 also wants a ceiling height of 2.5m or more across at least 75 per cent of each home's internal area. Older Soho upper floors with low ceilings can fail that test, which your designer should check first.

The bedrooms have their own minimums. Under Policy D6 a single bedroom must be at least 7.5 square metres and 2.15m wide, and a double or twin at least 11.5 square metres. The policy also favours dual aspect homes and normally avoids single aspect ones, which is hard on a deep, narrow Soho floor with windows only at the front. Settling the layout against these numbers early decides how many flats the floor really yields.

Sound and fire separation between new flats in Soho

Between the new flats, Part E applies. Approved Document E sets a lower sound insulation performance where flats come from a material change of use: 43 dB airborne through separating walls and floors, and impact sound on floors held to 64 dB at most. On timber floors in a period Soho building that means independent ceilings, resilient bars, acoustic mineral wool and a floating floor above. We build those layers in the order the acoustic design sets and leave room in the programme for pre-completion testing.

Part B governs fire. Each new flat needs fire separation from its neighbours and from the common stair, a protected escape route, fire stopping wherever pipes and cables pass through a floor or wall, and interlinked smoke detection. In a tall, narrow building with a single stair as the only way out, the fire strategy your designer prepares sets the door ratings and the stair enclosure, and we build to it.

Building control, CIL and addresses for new Soho flats

A conversion changes the layout, so it cannot go in to Westminster on a building notice and goes in as full plans. Westminster charges CIL per square metre on new dwellings of any size, and its CIL charging schedule first came into effect on 1 May 2016. The liability falls on the owner, not the builder, but it has to be settled before the start, because a commencement without the right forms can add surcharges to the Soho scheme.

Each new flat also needs its own services and identity. That means a separate electricity supply and meter, a separate gas or electric heating system, its own water arrangement where the supplier requires it, and a new postal address through Westminster's street naming and numbering service. Where a party wall is cut into or built on, the building owner serves notice under the Party Wall Act, and the work proceeds on the neighbour's written consent or an award. We coordinate the utility connections around the building programme.

• Protected escape stairs and fire-rated flat entrance doors
• Separate gas, electricity and water supplies for each flat
• Splitting a large flat in two, or joining two flats into one

VOA Council Tax stock of properties, March 2025, for the Fitzrovia West & Soho statistical area, which also covers west Fitzrovia. Counts rounded by the VOA.

Useful next reading for a flat conversions project in Soho: structural alterations in Soho, flat conversions across Westminster, building control sign-off for a conversion, party walls in a flat conversion, flat conversions anywhere in London and Getting Planning Permission.

Why Soho Homeowners Choose GS Renovation

A conversion in an occupied Soho building needs a builder who can stage the work floor by floor and keep the paperwork straight. We work from your designer's consented drawings and fire strategy, give you a written programme that shows each flat's start and finish, and keep dated photographs of the fire stopping and sound layers before they are covered. The registered electrician and the engineer on the Gas Safe Register certify their own work, and we hand those certificates over with the building control completion.

• Itemised pricing, so you can see what every stage costs
• Each flat's new electrics signed off by a registered electrician for Part P
• 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.