House Extensions Wandsworth
Single storey rear and double storey extensions in Wandsworth, 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 plans and builds house extensions throughout Wandsworth, working with the Victorian terraces, red-brick mansion blocks and riverside homes that define the borough. We take rear, side-return and wrap-around projects from foundations and steelwork through to a finished, decorated space.
In Wandsworth, 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 Wandsworth: 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 Wandsworth
Wandsworth range: choose above
Side-return and rear extensions in Wandsworth
The classic Wandsworth extension fills the side return of a period house in SW12 or SW17, widening a narrow kitchen into a bright, open-plan room that runs out towards the garden. We dig and pour the foundations, build the new walls, install the steel beams that carry the original rear wall, and construct the roof, often with rooflights or a flat lantern to pull daylight deep into the plan.
Because these plots sit tight against neighbours, party wall matters are almost always in play. Excavating close to a boundary or building off a shared wall means you serve notice under the Party Wall Act as building owner; we supply the drawings, help you appoint a surveyor early if one is needed and keep the schedule on track. We then handle the full fit-out, from screed and underfloor heating to plaster, flooring and decoration, so you move straight into a finished room.
Housing in Wandsworth
Roughly 157,900 dwellings sit on the valuation list for Wandsworth. 28% are houses and 72% flats, and by age 43% predate 1919, 7% are interwar and 49% post-war. Since most homes here are flats, a flat in Wandsworth has no householder permitted development rights, so extending one needs planning permission and the freeholder's consent.
Conservation areas, Article 4 and the levy on a Wandsworth extension
Only 28% of Wandsworth's homes are houses and 23% are terraced houses, so an extension here is usually a terrace job, and the street's designation decides the route. Wandsworth's conservation area FAQ lists front and side extensions of one storey or more, and two storey rear extensions, among works that need planning permission in a conservation area. A side return infill counts as a side extension, so on those streets it is an application from the start. A single-storey rear extension within the national limits can still be permitted development there, except where an Article 4 direction covers extensions, as it does on the Latchmere Estate.
A larger Wandsworth extension also has to be checked against the Community Infrastructure Levy. Wandsworth Council approved its CIL Charging Schedule at full Council on 11 July 2012 and it came into effect on 1 November 2012. Its residential rate is set separately for the Nine Elms and Roehampton charging zones and for the rest of the borough. An extension adding less new floor space than the threshold in the CIL regulations is not liable at all. A bigger one can usually claim the residential extension exemption, but the claim, and the council's commencement paperwork, have to be in before work starts, so we check the floor area while the plans are drawn.
Planning and permitted development in Wandsworth
Whether your extension is permitted development or needs a full planning application depends entirely on the property. A modest single-storey rear extension on a Victorian terrace in SW18 may fall within permitted development rights, while a double-storey or wrap-around scheme, any extension to a flat, and side or roof extensions in a conservation area will usually need permission from Wandsworth Council. In a conservation area a single-storey rear extension can still be permitted development within the limits, unless an Article 4 direction removes it. We assess your title, your position and any Article 4 restrictions before drawing anything up.
Whichever route applies, the structure itself is controlled under building regulations, so foundations, steel, drainage and insulation are all inspected and signed off by building control. We coordinate the drawings with your architect or technician, the council submission where one is required, and the programme around the party wall notices you serve, so you have a single team accountable from the first survey to the final building control certificate.
Kitchen extensions in Wandsworth
72% of homes in Wandsworth are flats, and a flat has no householder permitted development, so a ground-floor flat's kitchen extension needs planning permission from Wandsworth Council and the freeholder's consent. Most kitchen extensions here are on the 28% of homes that are houses. The fit-out is priced on its own page, kitchen renovation in Wandsworth; the build figures are in the table above.
Double storey extensions in Wandsworth
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 Wandsworth often needs planning permission from Wandsworth Council. It is a job for the 28% of homes that are houses; a flat cannot add a storey this way. Wandsworth has 46 conservation areas, ranging from a short street such as Deodar Road to a large area such as West Putney (council source). Our double storey extension page explains the build, at £1,800 to £2,600 per m² across both floors.
- Single and double storey extensions
- Foundations, groundworks and steel frames
- Steel goalpost frames where the rear wall opens up
VOA Council Tax stock of properties, March 2025, for all 38 statistical areas in Wandsworth. Counts rounded by the VOA.
Why Choose GS Renovation in Wandsworth
Extensions in Wandsworth mean tight plots, shared boundaries and a council that scrutinises period and riverside streets. GS Renovation manages the whole job, from groundworks and steel to planning or permitted development advice and building control. With our founder's 30+ years on the tools, you get one accountable team and a properly certified, finished extension.
- Photographs kept at each stage for your records
- Garden levels and access made good where the build meets outside
- Drainage diverted or built over with the right approval in place
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 Wandsworth
Do you charge for a survey before quoting house extensions in Wandsworth?
A house extensions survey in Wandsworth costs nothing, and it is part of quoting rather than a service to bill for. GS Renovation allows enough time at SW18 to check the mixed period and post-war details that move a figure within £2,000 to £2,800 per m² for a rear extension (indicative), and to plan the order: the steel into the house is designed before the rear wall comes down. Nothing is owed if you go elsewhere in Wandsworth.
Will my Wandsworth rear extension need planning permission or is it permitted development?
A modest single-storey rear extension on a terraced house may be permitted development, but larger, double-storey or wrap-around schemes, side or roof extensions in a conservation area, and anything an Article 4 direction covers usually need a planning application to Wandsworth Council. A single-storey rear extension in a conservation area can still be permitted development within the limits. Either way the structure needs building regulations sign-off. We check your specific position before design and manage whichever route applies.
Does a Wandsworth extension near a tree need deeper foundations?
It can. Roots pull moisture out of clay, and a trench beside a thirsty tree may meet ground that shrinks back each summer, so the engineer can call for a deeper dig or a piled design. The Wandsworth Council inspector looks at the open trench before concrete arrives, and the depth is agreed on the ground actually exposed.
Does my Wandsworth extension have to meet current insulation standards?
Yes. Part L applies to every extension, covering walls, floor, roof and glazing. A wide run of sliding doors or a large lantern needs balancing with better insulation elsewhere, and an existing wall renovated as part of the project may need upgrading too. In a Wandsworth terrace the insulation is inspected before plasterboard or screed hides it.
Who signs off a Wandsworth extension when it is finished?
Building control, with a completion certificate once the final inspection is passed. That follows earlier visits at the foundation trench, the drainage, the floor slab and damp-proofing, the steel, and the roof structure. Wandsworth Council's building control can do this, and the certificate is what a buyer's solicitor in SW18 or SW11 will ask for when you later sell.
Where does rainwater go from a new Wandsworth extension roof?
Into a drain laid to the falls Part H sets out. A flat roof needs its own fall to an outlet or gutter, and the downpipe connects to surface water drainage or a soakaway where the ground suits. If the new footprint covers or sits near a public sewer, the water company's consent is needed before foundations go in, so the drainage is planned with the roof.
Does Wandsworth's fixed building control charge cover both a side return and a rear infill?
Wandsworth Building Control's fixed charges cover an extension with an aggregate floor area of up to 40 square metres. Aggregate means the parts are added together, so a side return and a short rear infill built as one project are measured as one floor area. Keep the combined figure in view while the layout is drawn. If it passes 40 square metres, the job moves out of that band, and the charge and the application are prepared on that basis from the outset.
Is a side extension likely to suit a house in the West Putney conservation area?
Plan with caution. The West Putney Conservation Area appraisal says side extensions are not encouraged because they interrupt the spaciousness between the houses that the architect intended. Wandsworth adopted eight updated conservation area appraisals under delegated powers on 31 August 2023, so read the current appraisal for your street before any design. In West Putney, a rear extension that keeps the gaps between houses open is the option that works with the appraisal rather than against it.
Can an old lean-to be cleared before extending a Totterdown Fields cottage?
Ask before it comes down. Under the Totterdown Fields Estate Conservation Area Article 4 direction, demolition of buildings and of front boundaries over 1 metre in height needs planning permission. Whether a particular lean-to or outhouse counts as a building for that purpose is a question for Wandsworth's planning team, and the answer belongs in writing before the skip arrives. If the front wall is over 1 metre high, taking it down for access needs permission too, so plan for materials to come through the house or along the rear.
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