House Extensions Sutton
Single storey rear and double storey extensions in Sutton, 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 Sutton, working with the generous plots that came with its 1930s semi-detached, terraced and interwar suburban houses. We handle kitchen extensions, single and double storey, rear, side return and wrap-around projects from foundations to final fit-out.
In Sutton, 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 Sutton: 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 Sutton
Sutton range: choose above
Kitchen, side return and double storey extensions in Sutton
The deep rear gardens and side access common to Sutton's interwar semis make them well suited to extending. Most owners start with a kitchen extension, a single storey rear extension that opens the back of the house into a large kitchen-diner. On a semi, a side extension along the passage between two houses reclaims dead ground for a utility or wider kitchen. On Sutton's terraced streets the equivalent is a side return extension, infilling the narrow strip beside the rear wing, usually single storey. A wrap-around combines rear and side, and a double storey extension adds a bedroom and en-suite above the new ground floor.
Every extension starts underground, and around Cheam, Carshalton and Wallington the engineer we appoint designs foundations to suit the local ground and any nearby trees, which matters on plots close to Nonsuch Park or Beddington Park where mature planting is common. Steel beams tie the new opening back to the existing house, the roof is built to match, and we complete the fit-out including plastering, electrics, heating and decoration.
Housing in Sutton
The Council Tax list puts Sutton at about 86,280 homes, 39% flats against 61% houses; 13% went up before 1919, 41% between the wars and 46% after 1945. Terraced houses make up 28% of homes here, and a rear extension on a terrace in Sutton digs foundations close to both neighbours, so notices to both are normal.
Sewers, floor area and design guidance for Sutton extensions
Two rules decide the paperwork for a Sutton extension before anyone draws the roof. First, in Sutton, building work that will be near or cross public sewers needs a full plans application rather than a building notice. A rear garden can carry a shared sewer serving several houses, so check the sewer records before the footprint is fixed. That route takes a minimum of 5 weeks to approve, and the water company may need to agree a build over too. Second, Sutton's fee schedule splits single storey extensions at 40m2, with a different fee on each side of that line, so the floor area on the drawings also sets the building control fee.
Sutton's adopted Supplementary Planning Documents include the Design of Residential Extensions and the Sutton Garden Suburb Conservation Area Management Plan. Where an extension needs planning permission, the design document is what the application will be read against, so read it before the depth, the roof form and the gap to the boundary are settled. Sutton runs a paid-for pre-application advice service, and written advice for householder applications will generally be provided within 10 working days. Holding that meeting before the drawings are finished costs far less time than redesigning after a refusal.
Planning and party walls in Sutton
Depending on the size and position, your extension may fall under permitted development or it may need a full planning application to Sutton Council. Larger rear extensions, anything to the front, two storey additions, side extensions in conservation areas and homes with existing restrictions usually need planning permission, while modest single storey projects often do not. A double storey rear extension is permitted development only within tight limits, no deeper than 3 metres and at least 7 metres from the rear boundary, so most need planning permission from Sutton Council, and in a conservation area two-storey and side extensions always do. The extra floor also means deeper foundations and heavier steel over the opening, sized by the engineer and inspected by building control at each stage. Flats have no permitted development rights at all. We assess your specific house early and tell you honestly which route applies before you commit.
Whichever planning route applies, the build itself must satisfy building regulations, and where the extension runs up to or along the boundary with a neighbouring semi the Party Wall Act comes into play. You serve the party wall notices as building owner. We give you the drawings and programme they need, build to any award, coordinate the building control inspections through foundations, steel and roof, and keep the site tidy and secure so you can carry on living in the house while the work goes ahead.
- Wrap-around extensions and infills
- Roof works and structural alterations at roof level
- Brickwork and mortar matched to the existing elevation
VOA Council Tax stock of properties, March 2025, for all 24 statistical areas in Sutton. Counts rounded by the VOA.
The GS Renovation Difference in Sutton
Sutton homeowners choose GS Renovation because we run the whole extension as one accountable project, from advising on permitted development versus a planning application to the groundworks, steel, roof and full fit-out. Our founder's 30+ years on the tools means we understand these interwar plots, their foundations and their party walls, and we deliver space that suits how the house actually works.
- Programme planned around party wall notice periods before excavation near a neighbour
- Foundation depth set after trial holes, drains and trees are checked
- Neighbours given notice before the noisy stages
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 Sutton
Is the price of house extensions higher in Sutton than elsewhere in South London?
Work on house extensions in Sutton is priced from scope, so it costs no more than the same house in Merton, typically £2,000 to £2,800 per m² for a rear extension (indicative). Costs rise in period stock and with awkward access, both checked at SM1. What neither changes is the order of work: the planning route is confirmed before drawings, and footings inspected before concrete. GS Renovation shows each as its own line.
Will my rear extension in Sutton need planning permission or is it permitted development?
Many single storey rear extensions on Sutton's interwar plots fall within permitted development, but larger projects, double storey additions, side extensions in conservation areas and homes with removed rights need a full application to Sutton Council. We check your specific house and its planning history at the outset so you know the correct route before any design work starts.
What party wall steps come with a rear extension on a Sutton semi?
If you dig within 3 metres of the attached neighbour's house and below its foundations, which rear extensions frequently do, one month's notice is required under the Party Wall Act. Cutting into the party wall to tie in or bear steel needs two months' notice. Serve early: a dissenting neighbour means surveyors agree an award before any digging begins.
How do trees near my Sutton house affect an extension?
Roots draw moisture from the ground, so foundations near large trees are dug deeper, and building control confirms the depth once the trench is open. On leafy suburban streets and plots close to Nonsuch Park or Beddington Park, trees in your garden or next door can decide the foundation design. Check whether a tree is protected with Sutton Council before any roots are cut.
What happens to drainage when a Sutton semi is extended at the back?
The extension often lands over the kitchen waste run and a manhole. That chamber can be relocated or given a sealed double cover, and new runs go in to Part H falls. Should the footprint straddle a shared or public sewer, you need written agreement from the water company to build over it, obtained in advance. A camera survey before design avoids surprises once digging starts.
Can a Sutton extension have a roof lantern and wide glazed doors?
Yes, but the glazing feeds into the insulation calculation, since Part L requires the whole extension to meet current standards. Structurally, a lantern needs a trimmed opening in the flat roof and wide doors need steel over them, both sized by the engineer. Fix their positions before the roof joists are ordered, and building control inspects the structure at each stage.
How soon after the final inspection does a Sutton extension get its completion certificate?
For an extension to a house, Sutton's inspection schedule says a completion certificate follows in 5 working days if the final inspection is OK and installer certificates are received. The second condition is where delays come from. The electrician's certificate, the record for any new boiler or hob from its registered installer, and the glazing certificates all have to reach building control, so collect each one as that trade finishes rather than chasing them at handover.
Do Sutton's Article 4 Directions stop a rear extension going ahead as permitted development?
On houses covered by the 1984 direction, yes. Under an Article 4 Direction confirmed in 1984, a planning application is required on the affected Sutton properties for extensions, dormer windows and other roof alterations. The Sutton Garden Suburb Article 4 Direction also withdraws permitted development rights for certain alterations and additions to certain houses on roads including Meadow Close, Woodend and Hawthorne Close. In a conservation area without an Article 4 direction, a single storey rear extension can still be permitted development. Before relying on it, use Sutton's paid permitted development advice to confirm whether the address is covered.
What if an earlier extension to our Sutton house was never signed off?
Regularise it before a sale forces the question. Sutton's fee schedule gives single storey extensions a regularisation fee above the normal fee, on both sides of the 40m2 line. Sutton treats failing to notify it as illegal, and the work may have to be corrected or a fine paid. Expect parts of the foundations, damp proof course, insulation and steel to be opened up, because the inspector has to see what was covered up.
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