Flat Conversions Uxbridge

Flat conversion in Uxbridge means turning a house into self-contained flats, or occasionally merging flats back into one house. Across the VOA statistical areas covering Uxbridge, Swakeleys and Brunel, houses are 53% of homes and 33% are semi-detached or detached, and the candidates are the larger houses. Hillingdon sets a firm threshold: Policy DMH 4 needs an original internal floor area of at least 120 sqm, with one unit per floor. Planning permission is always needed. We build the separating floors, walls, stairs, kitchens, bathrooms and services to the approved drawings.

In Uxbridge, 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 Uxbridge: 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 Uxbridge houses can be split into flats

Only a larger house qualifies. Hillingdon Policy DMH 4 requires the original building to have at least 120 sqm of internal floor area, and limits conversions to one unit per floor. It also only permits them where no more than 10% of properties on the residential street would become flats. So measure the original Uxbridge house before paying for drawings, and a street that already has several conversions may be at that limit.

Policy DMH 1 adds that every unit must be self contained, with its own kitchen and sanitary facilities and its own entrance. On a two storey house that usually means a new front door or a separate staircase for the upper flat, which changes the hallway, the stairs and sometimes the front elevation. Hillingdon's housing need evidence points to a substantial requirement for larger homes, particularly three bedroom properties, so a scheme that keeps a three bedroom flat, such as a ground floor flat with the garden, answers that need directly.

Housing in Uxbridge

About 12,630 homes are listed for Uxbridge, and the mix is 53% houses to 47% flats, with 71% built after 1945, 17% in 1919 to 1939 and 12% earlier. The side of a semi in Uxbridge is where a separate entrance for the upper flat is most often placed, and 17% of homes here are semi-detached.

Space standards for the new flats in an Uxbridge conversion

Room sizes are fixed by policy before the walls go up. Hillingdon Policy DMHB 16 requires every conversion to meet or exceed the latest internal space standards, and London Plan Policy D6 sets a single bedroom at 7.5 square metres or more and at least 2.15m wide. A double bedroom needs 11.5 square metres. Unless the borough sets a higher figure, Policy D6 also asks for at least 5 square metres of private outdoor space for a one or two person flat in Uxbridge, plus 1 square metre for each extra occupant.

Height and outlook decide the rest of the layout. Policy D6 sets a floor to ceiling height of 2.5m over at least 75 per cent of each new flat, which a lower upper storey or a room under the eaves may not reach. The policy also asks for dual aspect flats where possible and normally avoids single aspect ones. Because DMH 4 allows one unit per floor, each flat takes a whole storey, and windows in the side wall of a semi-detached Uxbridge house can give each one that dual aspect.

Sound and fire separation between flats in Uxbridge

The floors and walls between new flats carry the hardest building work in an Uxbridge conversion. Approved Document E sets sound insulation for flats formed by material change of use at 43 dB airborne for walls and for floors and stairs, and a maximum of 64 dB impact for floors and stairs. In a house with timber joists that usually means a new ceiling on resilient bars, acoustic insulation between the joists and a floating floor above, with sound testing before completion.

Fire separation under Part B follows the same lines. Each flat needs a protected escape route, fire doors onto any shared hall, interlinked smoke detection and sealed service penetrations through every separating floor. The existing timber stairs usually have to be enclosed, and the floor between flats upgraded to the fire resistance building control sets. We build this at first fix in the Uxbridge programme, with the building control inspector seeing the separating layers before they are covered.

Meters, addresses, neighbours and CIL on an Uxbridge conversion

Each new flat in Uxbridge needs its own supplies and its own address. That means separate electricity meters and consumer units, separate water supplies or a sub-metering plan, and a heating system for each flat. The owner applies to the council for street naming and numbering so post and utilities can find the new flats. We plan the meter positions and the incoming service routes at the start, because utility companies set their own lead times.

Two outside parties may be involved too. Where the work cuts into a party wall, the building owner serves notice under the Party Wall Act on the neighbour. Where the house adjoins a property owned by Hillingdon Council, the notice goes to the Mayor and Burgesses of The London Borough of Hillingdon. In Hillingdon the CIL applies to all proposals that add 100m2 of new floorspace or an extra dwelling, so a conversion creating a new flat in Uxbridge should check its liability before work starts.

• Separate gas, electricity and water supplies for each flat
• Separating walls built and lined for sound between flats
• Decoration, flooring and making good throughout, ready to let or sell

VOA Council Tax stock of properties, March 2025, for Uxbridge Common & Swakeleys, Uxbridge Central & Brunel and Uxbridge West. Counts rounded by the VOA.

For the wider picture around flat conversions in Uxbridge, see structural alterations in Uxbridge, flat conversions across Hillingdon, a building contractor for the whole conversion, the Party Wall Act when a conversion cuts a shared wall, flat conversions anywhere in London and Getting Planning Permission.

Why Uxbridge Homeowners Choose GS Renovation

A flat conversion in Uxbridge is a change of use under the Building Regulations as well as a planning matter, and the separating floors and walls have to pass inspection and testing. GS Renovation builds conversions from the approved drawings, taking the job from strip out to finished, separately serviced flats under one programme. Our founder and director, Abdelaaziz Saaid, has more than three decades of hands-on building. The owner or their designer secures the planning consent, and we have the registered trades' certificates ready for building control.

• Common parts, bin stores and cycle stores finished to the planning conditions
• Each flat numbered and supplied before the keys are handed over
• One point of contact from first survey to handover

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.