House Extensions Greenwich
Single storey rear and double storey extensions in Greenwich, 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 throughout Greenwich, from side-return infills on Victorian terraces in Charlton to rear additions on Eltham and Woolwich family homes. We handle foundations, steel, roofing and fit-out, and guide you through whether the work is permitted development or needs planning.
In Greenwich, 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 Greenwich: 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 Greenwich
Greenwich range: choose above
Rear and side-return extensions in Greenwich
The classic Greenwich extension opens up the back of a Victorian terrace by filling in the side return and pushing out to the rear. These SE7 and SE18 terraces have a narrow closet wing and an awkward L-shaped kitchen, so squaring off the footprint opens up the ground floor. We dig and pour foundations to suit the ground, then carry the existing wall on steel to create one open kitchen-diner.
Double storey and wrap-around extensions suit the larger plots found around Blackheath and the leafier streets of Eltham. Whatever the shape, we manage the groundworks, the steel, the new roof and the drainage as one job. Because homes near Greenwich Park often sit in conservation areas, we build to designs that respect the street, working from the architect's drawings the Royal Borough of Greenwich will want to see.
Housing in Greenwich
Greenwich counts roughly 125,080 homes for Council Tax; 22% are older than 1919, 17% interwar and 60% post-war, with 55% flats and 45% houses. Where most homes are flats, a flat in Greenwich has no householder permitted development rights, so extending one needs planning permission and the freeholder's consent.
Three checks that set a Greenwich extension's route before design
Start at the drain. Royal Greenwich requires a full plans application to build over or within three metres of a public sewer, so a building notice is off the table for an extension near one. Behind a Greenwich terrace the shared run to the sewer can cross the garden close to the back wall, where a rear extension would stand over or beside it. Establish where the sewer runs before the architect draws, because it decides the building control route as well as the footprint, and a full plans approval takes longer to arrive than a notice.
Then flood and trees. Royal Greenwich requires a Flood Risk Assessment for all developments in Flood Zones 2 and 3, including domestic extensions, so find the address on the Environment Agency flood map before the planning drawings are priced. In Royal Greenwich conservation areas you must give six weeks written notice for work to, or felling of, trees more than 75mm in diameter. In a conservation area, a tree near the footprint, or roots in the line of a trench, adds six weeks to the front of the programme. Give that notice as soon as the footprint is known, before any clearance starts.
Planning and permitted development in Greenwich
Not every extension in Greenwich needs planning permission. Many single storey rear extensions fall under permitted development, but in conservation areas side and two-storey extensions lose it, and a listed building needs listed building consent regardless, both common in SE3 and SE10. We assess your property early, tell you honestly whether you can build under permitted development or must submit a full application to the council, and handle the paperwork either way.
Whichever route applies, the structural side still needs building regulations approval, with building control inspecting the foundations, steel and drainage as work proceeds. Where your extension sits against a neighbour's boundary or a shared wall, the Party Wall Act comes into play too: you serve the notice as building owner (or your surveyor does), and we give you the drawings and programme it needs. We coordinate the planning and the building control so nothing stalls the programme on site in Woolwich or Charlton.
Kitchen extensions in Greenwich
55% of homes in Greenwich are flats, and a flat has no householder permitted development, so a ground-floor flat's kitchen extension needs planning permission from the Royal Borough of Greenwich and the freeholder's consent. Most kitchen extensions here are on the 45% of homes that are houses. The fit-out is priced on its own page, kitchen renovation in Greenwich; the build figures are in the table above.
Double storey extensions in Greenwich
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 Greenwich often needs planning permission from the Royal Borough of Greenwich. On the 31% of homes that are terraced, the neighbours' windows usually decide the depth. Royal Greenwich has 23 conservation areas, and the council's list marks which of them are under Article 4 directions (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
- Building control inspections at foundation, damp course and steel stages
- Roof works and structural alterations at roof level
VOA Council Tax stock of properties, March 2025, for all 35 statistical areas in Greenwich. Counts rounded by the VOA.
The GS Renovation Difference in Greenwich
Greenwich homeowners choose GS Renovation because we run the whole extension under one accountable team: coordinating the architect's drawings and the council application, then the groundworks, the steel and the full fit-out. With our founder's 30+ years on the tools, we know the borough's flats, houses and conservation rules, and we keep your home liveable and the site tidy throughout.
- Drainage diverted or built over with the right approval in place
- Paperwork and certificates handed over for when you sell
- Brick and mortar matched to the existing elevation
Reviewed jobs near Greenwich
1 MyBuilder review from Woolwich, with each customer's own job title:
- Replace kitchen extractor hob, Woolwich, 27 Apr 2024 (5 out of 5)
Read all 31 on our reviews page.
Built a new extension at rear of property. Laid foundations, drainage, raised floor, new roof and completed all fixtures and interior decoration…
Giorgio is an excellent and intelligent workman, and with very reasonable prices! He installed a kitchen extractor fan in a complicated situation…
George was brilliant. Lovely bloke, very reasonably priced and a perfectionist to boot. He completed our small kitchen renovation with care and great…
FAQ
Frequently Asked Questions about House Extensions Greenwich
What happens to the house extensions price if the scope changes in Greenwich?
The house extensions price in Greenwich moves visibly when the scope changes, because the quotation is itemised within £2,000 to £2,800 per m² for a rear extension (indicative). A change at SE10 is priced against the same lines rather than renegotiated, and any change touching the approvals, such as permitted development or a planning application to the Royal Borough of Greenwich, is flagged. GS Renovation issues a written variation and waits for approval.
Does my Greenwich extension need planning permission or is it permitted development?
Many single storey rear extensions are permitted development, but in Greenwich's conservation areas near the Park or Blackheath, side and two-storey extensions lose permitted development (a single-storey rear extension can still qualify unless an Article 4 direction removes it), a listed home needs listed building consent, and a flat has no householder permitted development at all, so in those cases a planning application to the Royal Borough of Greenwich is needed. We check your specific address first and advise before any design work begins.
Is there a sewer under where my Greenwich extension would go?
Find out before the design is fixed. Many terrace rear gardens carry a shared drain serving several houses, and where that is a public sewer, building over it or near it needs the water company's consent. A manhole close to the back wall is the usual giveaway. A camera survey of the drains shows the route and depth, which may mean diverting the run or shifting the extension footprint.
What does building control inspect while a Greenwich extension goes up?
The work is checked in stages. The inspector sees the foundation trenches open before concrete is poured, then the drainage before it is backfilled, followed by the damp course, the steel bearings, and the insulation before it is covered. A completion certificate from the Royal Borough of Greenwich follows the final visit. Building regulations apply to every extension, including those built under permitted development.
Digging foundations near my neighbour in Greenwich: what notice is needed?
If the trench comes within 3 metres of their house and goes below their foundations, the Party Wall Act requires one month's notice. The neighbour can consent or dissent, and dissent leads to a surveyor's award, sometimes with a record of their walls' condition. Serving early lets the notice period run while drawings and building control approval are being finalised.
When does the back wall of my Greenwich house actually come out for the extension?
Late, once the new structure is weathertight. The shell is built, the roof and glazing go on, and only then is the old rear wall propped, cut out and replaced with the steel beam, so the house stays closed for most of the build. The new walls, floor and roof must meet current Part L insulation standards, and the junction with the old house is detailed to avoid a cold bridge.
Does a Greenwich extension have to pay the Community Infrastructure Levy?
It can fall within CIL, and relief is not automatic. Royal Greenwich adopted its new CIL charging schedule on 24 July 2024 and it came into force on 26 July. Residential extensions and annexes, like self-build new homes, can claim relief using the published exemption forms. Treat the form as part of the planning paperwork. Raise it with Royal Greenwich while the application is live, and have the relief confirmed and filed with the approval before anyone digs a trench.
Can a first-floor rear extension be built in Charlton Village without planning permission?
No. Royal Greenwich's Urban Design Guide says first-floor rear extensions are not classed as permitted development in conservation areas, and Charlton Village Conservation Area was designated in 1971. So a planning application is the starting point. The area has a 2016 character appraisal describing what gives the streets their character. Read it before the architect sketches, and design the upper storey so it answers the points the appraisal raises.
Can a side extension go ahead under permitted development in the Rectory Field area?
No. Rectory Field is a conservation area, and side extensions are not permitted development in any conservation area. At the addresses listed in the Rectory Field Conservation Area Article 4 direction the control goes further: planning permission is also required for rear extensions and for window or door changes. So at those addresses even a single-storey rear extension, which elsewhere in a conservation area can often be built without an application, needs one. Check the list before any design fee is spent.
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