Flat Conversions Streatham

Flat conversion in Streatham turns a larger Edwardian or Victorian house into self-contained flats, or brings converted flats back into one home. Houses are 33% of homes here and 43% of all homes were built before 1919, so the candidates are the bigger period terraces and semis. Lambeth Policy H6 protects family houses under 130m2 as originally built, and each new flat must meet the London space standards. We build to the planning consent with the fire and sound separation between flats that building control will test.

In Streatham, 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 Streatham: 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 Streatham houses Lambeth will let you convert

The size of the house as first built decides whether a flat conversion can be considered. Lambeth Local Plan Policy H6 protects family dwellings of less than 130m2, as originally constructed, from conversion into flats, so a later extension does not lift a smaller house over the line. Measure the original floor area before paying for layouts. If the house falls under the threshold, the realistic options are to keep it as one home or to extend and improve it as a family house.

In Streatham, 21% of homes are terraced houses and 12% are semi-detached or detached, so the pool of houses big enough to qualify is limited to the larger period properties. Planning permission is always needed to turn a house into flats, and the owner or their designer applies for it. The London Plan counts residential conversions that create net additional homes among the small site forms of intensification it supports.

Housing in Streatham

About 27,640 homes are listed for Streatham, and the mix is 33% houses to 67% flats, with 29% built after 1945, 27% in 1919 to 1939 and 43% earlier. Since most homes here are flats, a flat in Streatham can be split or combined only with the freeholder's consent, and changing the number of homes usually needs planning permission as well.

Unit mix, front doors and parking under Policy H6

Where a Streatham house is large enough, the same policy asks for a mix of unit sizes, including, where practicable, a family-sized home on the ground floor with direct access to the rear garden. That usually fixes the plan: a larger ground floor flat taking the garden, with smaller flats above sharing the stair. A layout of identical one bedroom flats is unlikely to meet the policy, so agree the mix with your designer before drawing kitchens and bathrooms.

The Lambeth Design Guide adds that house to flat conversions should keep the look of a single family dwelling by not adding extra entrance doors, so the flats usually share the original front door and hall. In a controlled parking zone, occupiers of the extra units get no additional parking permits, which matters when you value the flats. Separate gas, electricity and water supplies, meters and new flat addresses through street naming and numbering all need arranging early.

Space standards and ceiling heights in a Streatham conversion

Every flat created by a conversion is expected to meet the London space standards. Lambeth Policy H5 expects new residential development, including conversions, to meet the minimum internal space standards in London Plan Policy D6, and the London Plan table counts conversions and changes of use as new dwellings. A single bedroom must be at least 7.5 square metres and 2.15m wide, and a double at least 11.5 square metres.

Height is the harder test in a period house. Policy D6 sets a minimum floor to ceiling height of 2.5m for at least 75 per cent of each flat's floor area. Tall Edwardian ground and first floors often pass, but a second floor under the roof slope often does not, which can decide how many flats the building will really take. The space standard sits in the planning system rather than the building regulations, so it is settled at the planning stage.

Fire and sound separation between Streatham flats

A converted house needs each flat separated from the next for fire under Part B and for sound under Part E. The timber floors of an Edwardian house are the weak point, so the upgrade approved by building control typically means lifting boards, adding mineral wool between the joists, fixing resilient bars and fire-rated board below, and sealing every service penetration. The stairs and shared hall become a protected escape route, and each flat gets its own fire-resisting entrance door.

Approved Document E sets the sound targets for flats formed by a material change of use: 43 dB airborne for walls and for floors and stairs, and 64 dB maximum impact for floors and stairs. Pre-completion testing shows whether the build meets them, so we detail the floors and party walls to clear the figures before testing rather than after. Where the work cuts into a party wall, the building owner serves the Party Wall Act notices and the work waits for written consent or an award. Lambeth treats that as a civil matter it has no role in.

• Separate gas, electricity and water supplies for each flat
• Insulation to the walls, roof and floors the conversion touches
• New soil stacks, wastes and bathrooms stacked floor over floor

VOA Council Tax stock of properties, March 2025, for all 7 statistical areas in Streatham. Counts rounded by the VOA.

Next steps that tend to follow flat conversions in Streatham: structural alterations in Streatham, flat conversions across Lambeth, builders in London who take on conversions, party walls in a flat conversion, flat conversions across London and Renovation Budget & Contingency.

Trusted Flat Conversions in Streatham

A conversion joins structure, fire separation, acoustics, drainage and several kitchens and bathrooms in one building, and the order matters. We build from your planning consent and building regulations drawings, run the separating floors and walls before the fit-out, and keep the evidence the building control inspector and the sound tester will ask for. You or your agent handle the planning application, and we give you the programme and completion records that support the sale or letting of each flat.

• Dust screens and floor protection in occupied homes
• Every flat checked against the space standard before the layout is priced
• Common parts, bin stores and cycle stores finished to the planning conditions

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.