House Extensions Charlton
Single storey rear and double storey extensions in Charlton, 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 Charlton, on its Victorian and Edwardian terraces with rear closet wings and side returns and on its interwar houses, where a well-planned rear or side-return build adds the most. We handle groundworks, steel, roofing and full fit-out as a single project.
In Charlton, 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 Charlton: 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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Charlton range: choose above
Side-return and rear extensions in Charlton
The classic Charlton project fills in the side return beside the rear closet wing, turning a narrow galley kitchen into a bright, wide kitchen-diner. A single storey rear or wrap-around extension works well on the deeper plots found across SE7. We dig and lay the foundations, form the openings with engineer-sized steel, build the walls and fit a flat or glazed roof to bring light deep into the plan.
Many of these terraces share a boundary and a party wall with the neighbour, so you serve the correct party wall notices as building owner, using the drawings we give you, before we excavate close to the line or build off a shared wall. From the first trench to the last coat of paint, one team manages the groundworks, the structure, the glazing and the internal finishes, keeping the occupied home clean and the programme moving.
Housing in Charlton
By the valuation list's count, Charlton holds about 9,540 homes, 51% houses and 49% flats; by age, 29% were built before 1919, 22% between the wars and 49% since 1945. Terraced houses make up 35% of homes here, and a rear extension on a terrace in Charlton digs foundations close to both neighbours, so notices to both are normal.
How a Charlton side return infill is measured and charged
Where an extension opens up an existing elevation into an open-plan layout, Royal Greenwich adds half the floor area of the adjacent rooms to the chargeable area. A Charlton side return infill often does that: the side wall of the closet wing and part of the back wall come out, and the kitchen and rear room join the new space. Royal Greenwich charges one line for a domestic single storey extension not exceeding 10m2 and another for 10 to 60m2, so the rooms being opened into can move a narrow infill into the larger band.
Planning follows the address. A side return infill counts as a side extension, and in a conservation area such as Charlton Village Conservation Area a side extension is not permitted development, so it needs planning permission. The Royal Greenwich Urban Design Guide adds that in conservation areas a first-floor rear extension does not count as permitted development either. Single storey rear extensions keep their permitted development rights there, unless an Article 4 direction takes them away. At the addresses named in the Rectory Field Conservation Area Article 4 direction, side and rear extensions both need planning permission. Check all of this before paying for drawings, because the design changes once an application is certain.
Planning and permitted development in Charlton
Whether your Charlton extension is permitted development or needs a full planning application depends on the property and the design. Many single storey rear extensions fall under permitted development rights, but limits on size, height and materials apply, and a double storey extension, a side or wrap-around extension in a conservation area, and any extension to a flat need permission from the Royal Borough of Greenwich. We assess your specific SE7 house before committing to a route.
Whatever the planning position, the structural work itself is governed by building regulations, so foundations, steel beams and drainage are inspected and signed off by building control regardless. We advise honestly on which consents apply, arrange what is needed and coordinate the paperwork so you know where you stand before work begins, avoiding costly surprises once the build is under way.
Kitchen extensions in Charlton
69% of the houses in Charlton are terraced. On a terrace the kitchen extension is built out from the back, into the side return where the house has one or across the full rear width, and a steel beam takes the old back wall so the kitchen and the new room become one space. The fit-out is priced on its own page, kitchen renovation in Charlton; the build figures are in the table above.
Double storey extensions in Charlton
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 Charlton often needs planning permission from the Royal Borough of Greenwich. On the 35% of homes that are terraced, the neighbours' windows usually decide the depth. Charlton Village Conservation Area was designated in 1971 and has a 2016 character appraisal (council source). Our double storey extension page explains the build, at £1,800 to £2,600 per m² across both floors.
- Drainage diversion and build-over agreements with the water authority
- Brickwork and mortar matched to the existing elevation
- Party wall process explained, and the extension built to the award
VOA Council Tax stock of properties, March 2025, for Charlton Village, Charlton Slopes and Hornfair Park. Counts rounded by the VOA.
Why Charlton Homeowners Choose GS Renovation
Charlton homeowners choose GS Renovation because we build the whole extension in-house, from foundations and steel to roofing and finishes, with one team accountable throughout. We are honest about whether you need planning or can build under permitted development, we give you what your party wall notices need and handle building control, and our founder's 30+ years on the tools back every job.
- Permitted development checked before you pay for a planning application
- Registered in England, Companies House no. 14611254
- Programme planned around party wall notice periods before excavation near a neighbour
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 Charlton
Is the price of house extensions higher in Charlton than elsewhere in South East London?
The price of house extensions in Charlton is set by the housing rather than the postcode, within £2,000 to £2,800 per m² for a rear extension (indicative). Older construction takes more making good than recent work, and access at SE7 affects the labour line. GS Renovation prices the property in front of it, because the depth of neighbouring Charlton foundations decides how deep the new footings go, rather than applying a Charlton multiplier.
Will my Charlton side-return extension need planning permission?
Many single storey side-return and rear extensions in Charlton fall under permitted development, but size, height and material limits apply, flats always need a planning application to the Royal Borough of Greenwich, and in a conservation area a side-return infill counts as a side extension and needs one too. We assess your SE7 property first, then arrange the correct consents. Either way, building control still inspects and signs off the structural work.
How deep do extension foundations go on Charlton clay?
As deep as the engineer and building control require for the ground found on the day. Clay moves with moisture, and nearby trees draw water out of it, so foundations close to a tree go deeper or use a different design. Building control inspects the open trench before concrete is poured, which means the depth is confirmed in the ground, not guessed from a drawing.
What if a drain runs under the site of my Charlton extension?
Deal with it before a single trench is dug. Part H sets the falls any diverted pipe must keep, and where the pipe beneath is a public sewer rather than your own drain, the water company has to agree to you building over or beside it, which is not instant. A private run can often be rerouted around the footprint or bridged with a lintel. A camera survey tells you which you have.
Which building control inspections does a Charlton extension go through?
Several, at points where work would otherwise be hidden. Typically the foundation trench before concrete, the drainage before backfilling, the damp-proof course and floor slab, then steel and roof structure, and finally completion. Part L means the insulation in walls, floor and roof is checked too. Each visit is booked before the next stage covers the last.
Can I extend a Charlton flat the way a house can?
No. Permitted development belongs to houses; a flat has none. Since nearly half of Charlton homes are flats, many owners discover that even a modest rear addition needs a full application to the Royal Borough of Greenwich. The lease normally controls the external walls too, so the freeholder must agree. Building regulations apply in every case, whatever the planning route.
Does a Charlton extension near the river need a Flood Risk Assessment?
If the address is in Flood Zone 2 or 3 and the extension needs planning permission, yes. Royal Greenwich asks for a Flood Risk Assessment with every development in Flood Zones 2 and 3, domestic extensions included. Charlton Riverside Conservation Area, designated in 2018 and 2021, takes its name from the riverside, so homes near it are worth checking on the flood map early. The assessment goes in with the planning application and can set the new floor level.
Does a large Charlton extension have to pay the Community Infrastructure Levy?
Only a large extension comes into scope, and even then relief is available. Royal Greenwich adopted its current CIL charging schedule on 24 July 2024, and the council accepts relief claims for self-build residential extensions and annexes on its published exemption forms. The claim has to be made and accepted before work starts on site. On a big Charlton side and rear scheme, put the form in the programme next to the building control notice, not after the first dig.
Does cutting back a garden tree for a Charlton extension need notice?
In a conservation area, yes, for any tree over the size limit. Royal Greenwich must have six weeks notice in writing before anyone works on, or fells, a tree there more than 75mm in diameter. Roots cut for a foundation trench and a crown lifted for scaffold can both count. Send the notice with the planning application, so the six weeks has run before the dig starts.
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