House Extensions Lambeth
Single storey rear and double storey extensions in Lambeth, planning, structure and build under one contract.
- Rated 4.9 from 31 reviews on MyBuilder
- Single-storey rear extension from £40,000
- Free site survey, itemised quote
GS Renovation builds extensions across Lambeth, adding space to period homes from Streatham to Kennington. We handle foundations, steelwork, roofing and fit-out, and guide you through whether your project is permitted development or needs a planning application to Lambeth Council.
In Lambeth, a single-storey rear extension typically starts from £40,000, or £2,000 to £2,800 per m² (indicative London ranges, Architecture for London, Resi, MyBuilder and Checkatrade, 2026). GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Lambeth: the structural engineer we appoint designs the structure, we build it, and building control signs it off.
Price guide
| Work | Indicative London range |
|---|---|
| Single-storey rear extension | from £40,000 |
| Rear extension, per m² | £2,000 to £2,800 |
| Side return, per m² | £2,400 to £3,200 |
| Wraparound, per m² | £2,400 to £3,200 |
| Double storey, per m² | £1,800 to £2,600 |
| Basement extension | see the basement page |
Indicative London ranges (Architecture for London, Resi, MyBuilder and Checkatrade, 2026), not a quotation. Prices checked September 2026. Full breakdown: Extension Costs & Planning.
Quick estimate for Lambeth
Lambeth range: choose above
Rear and side-return extensions in Lambeth
The classic Lambeth extension fills the side return of a Victorian terrace or wraps around the rear closet wing, turning a dark galley kitchen into an open living space that looks onto the garden. Around Brockwell Park and Clapham Common we dig and pour new foundations, tie into the existing solid walls, and install steel beams so the back of the house can open up fully. Everything is built to current building regulations. A kitchen extension is often the point of the work: on a Lambeth terrace it usually combines the side-return infill with a short rear addition, so the kitchen runs along the old side wall under rooflights and the dining end opens onto the garden. Where the upper floor is extended too, as a double storey extension, the steel over the new kitchen carries that load as well, so the two are designed together.
On the larger Georgian and Regency houses of Kennington and Vauxhall we build double storey and full width additions where the plot allows. Because many of these homes are listed or within conservation areas, external work often needs planning permission from Lambeth Council as well as building control approval. We coordinate the drawings and the application with your architect or designer, and give you what you need to serve party wall notices where the extension runs up against a neighbour.
Housing in Lambeth
Count the homes in Lambeth and you get about 148,600: 46% built since 1945, 14% between the wars and 40% before 1919, with flats at 77% and houses at 23%. Most homes here are flats, and a flat in Lambeth has no householder permitted development rights, so extending one needs planning permission and the freeholder's consent.
What three Lambeth conservation area statements say about extending
Lambeth has 62 conservation areas covering approximately 30% of the borough, and three of their statements say something direct about extensions. The Kennington Conservation Area Statement says rear extensions are only likely to be acceptable where they would not harm the spatial character of the area. The Vauxhall Conservation Area Statement says front and side extensions are likely to be resisted. The Brixton Conservation Area Statement says there is often little scope for extensions other than on rear elevations and on some rooftops. Read together, the rear is the realistic place to extend in all three, and in Kennington even the rear is judged against the spatial character of the area.
That shapes the drawing before it shapes the build. A rear extension in one of these areas is drawn to show how it keeps that character: its depth, its height against the first floor windows and the gap it leaves to the boundary. Where a pre-application meeting would help, Lambeth charges its higher householder pre-application fee for a house or flat in a conservation area, so we prepare measured drawings and photographs first to get full value from it. Lambeth says a householder application should get a response in 8 weeks, and we set the start date from the decision, not the submission.
Permitted development or planning in Lambeth
Not every Lambeth extension needs planning permission. A modest single storey rear extension on an unlisted house may fall under permitted development rights, letting us start sooner. But those rights are restricted within many of the borough's conservation areas, which cover large parts of Clapham, Brixton and Streatham: a single-storey rear extension can still qualify there within its limits unless an Article 4 direction removes it, while side and two-storey extensions need permission. A listed house needs listed building consent whatever the route. We assess your property early and tell you honestly which route applies before any commitment.
Where a full application is required, we coordinate the process with Lambeth Council and coordinate the structural engineer, so the design that gets consented is the one we can actually build. Party wall matters are common on the borough's tight terraced plots, so you serve notices in good time. From groundworks to the final coat of paint, one team keeps your SW9 or SE11 extension moving.
Kitchen extensions in Lambeth
77% of homes in Lambeth are flats, and a flat has no householder permitted development, so a ground-floor flat's kitchen extension needs planning permission from Lambeth Council and the freeholder's consent. Most kitchen extensions here are on the 23% of homes that are houses. The fit-out is priced on its own page, kitchen renovation in Lambeth; the build figures are in the table above.
Double storey extensions in Lambeth
Under permitted development a two-storey rear extension can go no more than 3 metres beyond the original rear wall and must stay at least 7 metres from the rear boundary, and in a conservation area it is not permitted development at all. Many gardens are too short for the 7 metre rule, so a double storey extension in Lambeth often needs planning permission from Lambeth Council. It is a job for the 23% of homes that are houses; a flat cannot add a storey this way. Lambeth has 62 conservation areas covering approximately 30% of the borough (council source). Our double storey extension page explains the build, at £1,800 to £2,600 per m² across both floors.
- Party wall process explained, and the extension built to the award
- Steel goalpost frames where the rear wall opens up
- Full fit-out, finishing and making good
VOA Council Tax stock of properties, March 2025, for all 35 statistical areas in Lambeth. Counts rounded by the VOA.
Trusted House Extensions in Lambeth
Lambeth homeowners choose GS Renovation because we manage the whole extension, the planning route, the foundations, the steel and the fit-out, as a single accountable project. We know how Lambeth Council treats conservation areas and listed homes, and we build to last. With our founder's 30+ years on the tools, you deal with one experienced team from first drawing to handover.
- Clean, tidy and reliable tradespeople
- Weathertight shell reached before the fit-out begins
- Insulation and thermal detailing to current regulations
Built a new extension at rear of property. Laid foundations, drainage, raised floor, new roof and completed all fixtures and interior decoration…
George was brilliant. Lovely bloke, very reasonably priced and a perfectionist to boot. He completed our small kitchen renovation with care and great…
George always kept to commitments and arrived on time. He offered helpful suggestions during his initial visit and promptly provided a reasonably…
FAQ
Frequently Asked Questions about House Extensions Lambeth
How does your house extensions price in Lambeth compare with a national firm's?
A GS Renovation price for house extensions in Lambeth compares well with a national firm's because there is no head office to fund, and both should sit within £2,000 to £2,800 per m² for a rear extension (indicative). GS Renovation is the contractor doing the work at SW9, not a broker adding a margin. Compare the scope, including permitted development or a planning application to Lambeth Council, not just the total.
Does my Lambeth extension need planning permission or just building regs?
A modest single storey rear extension on an unlisted house may be permitted development, needing only building regulations. But if your home is listed you will need listed building consent, and in one of Lambeth's conservation areas, which cover much of Clapham and Brixton, side and two-storey extensions need planning permission from Lambeth Council, while a single-storey rear extension can still be permitted development unless an Article 4 direction applies. We check the position for your address before you commit.
Can a ground-floor conversion flat in Lambeth be extended?
Only with planning permission from Lambeth Council, because permitted development rights apply to houses, not flats. The freeholder's consent comes first, and owners of the upper flats may hold rights over the garden or the rear wall. Building regulations approval applies as well. With 77% of Lambeth dwellings recorded by VOA as flats, this is a common route.
What does a side return infill involve on a Lambeth Victorian house?
Where the house has a side return, the infill usually runs to the boundary, so a party wall notice goes to the neighbour for building on the line, plus one month's notice if foundations dig within 3 metres below theirs. The side wall of the house is replaced by a steel beam. Drains often run along the return, so they are surveyed first.
How does a conservation area affect my Lambeth extension?
It removes permitted development rights for side extensions and can tighten what is allowed at the rear, so planning permission from Lambeth Council is more likely. Conservation areas cover much of Clapham and Brixton, so this is a live question there. Materials, roof form and glazing will be judged against the street's character. Building regulations apply whichever route is taken.
What insulation standards apply to a glazed Lambeth extension?
Part L requires the new walls, floor and roof to meet current insulation standards, and large glazing areas count against the overall heat loss. A glass rear wall with rooflights may need better-performing glass or extra insulation elsewhere. The old back wall of a solid-walled period house stays uninsulated inside the new room, which the design should allow for.
Which Lambeth conservation areas have Article 4 Directions on external alterations?
Lambeth lists all or parts of Albert Square, Hyde Farm, Lansdowne Garden, Leigham Court Estate, Park Hall Road, St Marks, Stockwell Park, Streatham Lodge and Vauxhall conservation areas as having Article 4 Directions on external alterations. In any conservation area, side extensions and rear extensions of more than one storey need planning permission. A single storey rear extension to a house can still be permitted development unless a direction removes that right. We read the direction for your street before design, because it can turn a quick start into an 8 week wait.
Can a side infill beside a Lambeth closet wing go up two storeys?
On a heritage asset, generally not. The Lambeth Local Plan policy on building alterations and extensions says infill extensions alongside closet extensions or rear returns should generally be single storey on heritage assets. A listed building is a heritage asset, and Lambeth Council states the borough has over 2,000 of them. We confirm the status of the house first, then design the infill as a single storey with rooflights and find the extra bedroom or bathroom space somewhere else in the plan.
Does a two storey Lambeth extension go through building control differently from a single storey one?
It is charged as a different item. Lambeth's building control charges list a single storey domestic extension up to 40m2 and a two storey domestic extension up to 40m2 separately, each with its own total. The application has to describe the scheme actually being built. If a design grows a second storey while planning is under way, we update the building control application to match before work starts, so the inspections and the completion certificate cover what stands at the end.
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