House Extensions Wimbledon
Single storey rear and double storey extensions in Wimbledon, 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 extensions across Wimbledon, from side-return infills on SW19 terraces to full rear and wrap-around additions near Wimbledon Common. We handle foundations, steelwork, roofing and fit-out as one accountable project for families in Merton.
In Wimbledon, 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 Wimbledon: 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.
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Side return and rear extensions in Wimbledon
The bay-fronted terraces around Wimbledon typically have a rear closet wing and a narrow side return running alongside the kitchen. Infilling that side return, often combined with a rear extension, is the classic SW19 project. It widens a pinched galley kitchen into a proper open-plan kitchen-diner, floods the back of the house with light through rooflights and glazed doors, and opens onto the garden without losing much outdoor space.
We start with foundations and groundworks suited to the ground and any nearby trees, then bring in steel beams to carry the existing rear wall and the new roof. Because these terraces share boundaries, you usually need to serve party wall notice on the neighbour as building owner, and we give you the drawings it needs. We manage the excavation, the steel, the roof and the internal opening-up so the new and old parts read as one continuous space.
Housing in Wimbledon
By the valuation list's count, Wimbledon holds about 25,760 homes, 49% houses and 51% flats; by age, 52% were built before 1919, 10% between the wars and 38% since 1945. A flat in Wimbledon has no householder permitted development rights, so extending one needs planning permission and the freeholder's consent, which matters here because most homes are flats.
Extending a house in the Wimbledon North Conservation Area
Merton describes the Wimbledon North Conservation Area as the land east of the south east corner of Wimbledon Common, and north and east of Wimbledon Village. Inside any conservation area, side extensions, rear extensions of more than one storey and external cladding lose their permitted development rights, while a single-storey rear extension within the usual limits keeps them. Merton's Wimbledon North character assessment records considerable pressure to redevelop individual houses with much larger dwellings. That concerns replacement houses rather than extensions, but it shows what planners there are watching, so design the addition so the original villa can still be read.
Timing follows the designation. Merton's fast track householder decision is up to 30 days from validation outside a conservation area and up to 46 days inside one, so a Wimbledon North house should allow the longer period before builders and steel are booked. Merton's Category D householder pre-application advice includes a short virtual meeting only, which suits a single question about depth, height or materials rather than a full design review. Prepare clear drawings and one or two specific questions before booking it.
Planning and permitted development in Merton
Not every Wimbledon extension needs a planning application. Many single-storey rear and side-return projects fall under permitted development rights, provided they stay within the limits on depth, height and materials. Double-storey extensions, work on the front elevation, side extensions in conservation areas, and listed homes usually do need a full application to Merton Council, and permitted development rights can be restricted in some parts of SW19.
We assess your specific property before drawing anything, because the right route depends on your plot, your neighbours and whether local rights have been removed. Whichever path applies, the structural elements must still meet building regulations, which is separate from planning. Your architect or designer prepares the drawings and any planning submission to Merton Council; we build from them, arrange building control inspections and see the whole extension through to a finished, decorated fit-out.
Kitchen extensions in Wimbledon
51% of homes in Wimbledon are flats, and a flat has no householder permitted development, so a ground-floor flat's kitchen extension needs planning permission from Merton Council and the freeholder's consent. Most kitchen extensions here are on the 49% of homes that are houses. The fit-out is priced on its own page, kitchen renovation in Wimbledon; the build figures are in the table above.
Double storey extensions in Wimbledon
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 Wimbledon often needs planning permission from Merton Council. On the 32% of homes that are terraced, the neighbours' windows usually decide the depth. Merton's immediate Article 4 Direction for small HMOs in 13 wards, including Lower Morden, Wimbledon Park and Wimbledon Town, started on 24 March 2026 (council source). Our double storey extension page explains the build, at £1,800 to £2,600 per m² across both floors.
- Side-return and rear extensions
- Planning applications and permitted development assessments
- Full fit-out, finishing and making good
VOA Council Tax stock of properties, March 2025, for all 7 statistical areas in Wimbledon. Counts rounded by the VOA.
Why Choose GS Renovation in Wimbledon
GS Renovation gives Wimbledon homeowners a single team for the entire extension: foundations, steel, roof, a programme planned around party wall notice periods, and the full internal finish. We are straight about whether your project is permitted development or needs a Merton Council application, we build to building regulations, and our founder's 30+ years on the tools means fewer surprises on these period terraces.
- Garden levels and access made good where the build meets outside
- Honest updates if a date or a detail has to move
- Weathertight shell reached before the fit-out begins
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 Wimbledon
Does the cost of house extensions rise in a late Victorian or Edwardian Wimbledon property?
The cost of house extensions in a late Victorian or Edwardian Wimbledon property can rise a little within £2,000 to £2,800 per m² for a rear extension (indicative), mostly in making good rather than the structural work. Making good cornice, floors and plaster takes longer than the structural work at an SW19 address. GS Renovation allows for that in the quotation, and for the fact that the width of the opening into the house decides the steel.
Will my Wimbledon side-return extension need planning permission?
Often it will not. Many single-storey side-return and rear extensions in Wimbledon qualify as permitted development if they stay within the size and height limits. However, a side extension in a conservation area, a listed home, or one whose permitted development rights have been removed will need a full application to Merton Council. We check your property first and take whichever route applies.
Do Wimbledon clay soils affect extension foundations?
They can, particularly around the clay soils near Wimbledon Common. Clay shrinks and swells with moisture, and trees drawing water from it make that worse, so the foundation depth is set by the engineer and building control rather than a standard trench. Near large trees, deeper or piled foundations may be needed. That is settled after a trial pit, before the design is priced.
Does a wrap-around extension in Wimbledon need a steel post at the corner?
Usually. Where the side return infill meets the rear extension, the corner of the original closet wing is often removed, leaving the upper floors to be carried by a steel frame. The engineer designs a post and beam arrangement, with the post on its own foundation. Building control inspects the frame and foundations before the roof and floor are finished.
When does building control inspect a Wimbledon extension?
At each stage that will be covered up. Typically the foundation excavation before concrete, the drainage before backfilling, the steelwork and bearings, and the insulation before it is closed. Merton building control or a registered building control approver issues the completion certificate at the end. Missing one of those stages means opening work up again, so inspections are booked around the programme.
Will my new Wimbledon kitchen extension floor be level with the house?
It can be, but the levels are set before the slab is cast. The front of an SW19 terrace usually has a suspended timber floor, while the new extension will be a concrete slab with insulation. The new floor is set to match the finished level of the old one, taking into account screed, tiles and any underfloor heating.
How long does a Merton fast track decision take for a Wimbledon extension?
Up to 30 days from validation outside a conservation area and up to 46 days inside one. Validation is the start, not submission, so missing documents push the date back. In Wimbledon, confirm the designation first, because the longer period applies inside a conservation area and the build programme should allow for it.
Is Merton's Category D pre-application advice worth using for a Wimbledon extension?
For a focused question, yes. Merton's Category D householder pre-application advice includes a 15 minute virtual meeting only, so it suits one issue, such as the depth of a rear addition or a facing material, rather than a whole scheme. Send clear drawings in advance and write the questions down, so the meeting is spent on answers.
Could a large Wimbledon extension become liable for CIL?
It can. Merton says CIL will usually apply where permission is granted for at least 100 square metres of new-build gross internal area. A two-storey wrap-around on a Wimbledon villa can reach that size, so take the floor area off the drawings and ask Merton about liability early. Extending your own home normally qualifies for an exemption, but only if it is claimed before work starts, not after the slab is cast.
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