Flat Conversions Sidcup

A flat conversion in Sidcup starts from a house. Houses make up 60% of homes across the VOA statistical areas covering Sidcup, Lamorbey and Foots Cray Meadows, and the larger interwar semis and older detached houses can have the rooms and ceiling heights to divide. Splitting a house into self-contained flats needs planning permission anywhere, and Bexley judges it against its conversion code and space standards. We build the separating floors and walls, the protected hall and the separate services to the approved scheme.

In Sidcup, 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 Sidcup: 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.

Splitting a Sidcup house into flats under Bexley's conversion code

A Sidcup house to flats conversion has to meet Bexley's Design Guide SPD Part 2 code B 12, which requires appropriate internal space standards and no unacceptable impact on the streetscape or local amenity. From the street, Bexley wants the converted building to still look like one house, and it does not want new entrances added. In practice that means one front door, with the flats reached from a shared hall inside, and meters and bins placed so the frontage still reads as one house.

Every unit in the conversion also needs external amenity space, so a Sidcup semi with a long garden is easier to divide than one with a small yard. The garden can be split, with a side path giving the upper flat its own route to its share. We set out those paths, fences and bin stores as part of the build, since they are part of the approved scheme rather than extras added once the flats are finished.

Housing in Sidcup

On the valuation list Sidcup counts about 15,110 homes, 40% flats and 60% houses; 12% predate 1919, 30% are interwar and 57% post-war. The side of a semi in Sidcup is where a separate entrance for the upper flat is most often placed, and 27% of homes here are semi-detached.

Room sizes and ceiling heights for new Sidcup flats

Bexley measures each new Sidcup flat against the space standards set out in D 22 of its Design Guide SPD Part 1, and the London Plan counts a conversion as a new dwelling. London Plan Policy D6 then fixes the minimums: 7.5 square metres and 2.15m width for a one-bedspace bedroom, 11.5 square metres for a double or twin, and a 2.5m ceiling across 75 per cent of the flat.

Those ceiling heights often decide which Sidcup houses work. A tall pre-war storey can absorb a floating floor above and an independent ceiling below and still keep its height, whereas a lower post-war house may lose too much. The space standard is a planning test, not a building regulation, so the designer measures every room before drawing. We check finished heights as the build-ups go in so nothing falls short of the approved drawings.

Sound and layout between flats in a converted Sidcup house

Sound is the part of a conversion that is tested, not just inspected: separating walls and floors in flats formed by a change of use need pre-completion sound testing. Bexley wants them to reach Part E as a minimum, covering impact, airborne and flanking noise. The Approved Document figures are 43 dB airborne through a wall or floor and no more than 64 dB impact through a floor. In a timber-floored house that typically means an independent ceiling, resilient bars or hangers, mineral wool and a floating floor above.

Layout helps as much as materials. Bexley asks designers not to stack or set a living room or kitchen against a bedroom in the next flat, in any direction. So the upper flat's kitchen sits over the lower flat's kitchen where possible, and stairs are kept away from bedrooms. Fire separation between the flats and a protected escape route through the shared hall are built in the same stage, before any plaster goes on in the Sidcup house.

Separate services, addresses and drains for each Sidcup flat

Each new Sidcup flat needs its own gas, electricity and water supply, its own meters and, usually, its own boiler or heating system. The supply companies need the new addresses first, so street naming and numbering is applied for early and the utility requests follow. We run each flat's supplies to its own meter position in the shared hall or outside, and a registered electrician certifies each flat's installation separately.

The drains often need changing too, because an upper-floor kitchen and bathroom need a soil and waste route down the building. In Bexley a building notice cannot be used for building over or within 3m of a drain or sewer controlled by Thames Water, so a rear addition near the public sewer needs full plans. Where the conversion cuts into or builds on a party wall with the house next door, the building owner serves notice under the Party Wall Act before that work starts.

• Protected escape stairs and fire-rated flat entrance doors
• Steel beams and new openings built to the engineer's design
• Heating and hot water for each flat, gas by a Gas Safe registered engineer

VOA Council Tax stock of properties, March 2025, for Sidcup West, Sidcup East, Lamorbey and Foots Cray Meadows. Counts rounded by the VOA.

Alongside flat conversions in Sidcup, the pages that usually help next are structural alterations in Sidcup, flat conversions across Bexley, a building contractor for the whole conversion, the Party Wall Act when a conversion cuts a shared wall, how we handle flat conversions across London and Adding Value to a London Flat.

Why Sidcup Homeowners Choose GS Renovation

A flat conversion in Sidcup packs structure, fire, sound and services into one building, and the order matters. We strip out, form the separating floors and walls, run separate services and drainage to each flat's own meter position, build the protected hall and fit out each flat, working from the drawings and consent your designer secures. The founder brings more than three decades of hands-on building work. You get a written quote after a site visit and a written programme, and we arrange access for the sound test.

• Our own trades on site rather than a chain of subcontractors
• Each flat's new electrics signed off by a registered electrician for Part P
• Separating floors built to the acoustic detail the sound test checks

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.