Double-storey extensions across Greater London
Thinking about a double-storey extension for your Greater London home? Start with a free site visit: we measure up, check what the council will allow and give you honest guide figures on the day.
- Guide priceFrom £49,000 inc VAT
- PlanningUsually a householder application
- Towns covered105
- Site visitFree, no obligation
Towns in Greater London
- Abbey Wood
- Acton
- Barking
- Barnes
- Barnet
- Battersea
- Beckenham
- Becontree
- Bethnal Green
- Bexley
- Blackheath
- Bow
- Brixton
- Brockley
- Camden Town
- Canning Town
- Carshalton
- Catford
- Chalk Farm
- Chelsea
- Chessington
- Chingford
- Chislehurst
- Chiswick
- Coulsdon
- Cricklewood
- Croydon
- Dagenham
- Earlsfield
- East Barnet
- Edmonton
- Eltham
- Enfield
- Enfield Lock
- Feltham
- Finchley
- Friern Barnet
- Fulham
- Golders Green
- Greenford
- Greenwich
- Hampton
- Hanworth
- Harlesden
- Harringay
- Harrow
- Hayes (Hillingdon)
- Heston
- Highbury
- Holloway
- Hook
- Hornchurch
- Hounslow
- Ilford
- Isleworth
- Kilburn
- Leytonstone
- Manor Park
- Mitcham
- Morden
- Muswell Hill
- New Cross
- New Malden
- Norbury
- Northolt
- Notting Hill
- Orpington
- Palmers Green
- Peckham
- Pinner
- Plumstead
- Ponders End
- Purley
- Putney
- Richmond
- Roehampton
- Romford
- Ruislip
- Shepherds Bush
- South Croydon
- South Norwood
- South Ruislip
- Southall
- Stamford Hill
- Stepney
- Stratford
- Streatham
- Surbiton
- Sutton
- Thamesmead
- Tooting
- Tottenham
- Upper Norwood
- Uxbridge
- Wallington
- Walthamstow
- Wealdstone
- Welling
- Wembley
- West Ham
- Willesden
- Wimbledon
- Wood Green
- Woodford Green
- Worcester Park
Do I need planning permission in Greater London?
In England a two-storey rear extension is permitted development only if it projects no more than 3 m from the original rear wall, sits at least 7 m from the rear boundary, matches the roof pitch and uses obscure, non-opening side windows upstairs. Most two-storey extensions therefore go through a householder planning application, which costs £548 from 1 April 2026 and normally takes about 8 weeks.
The planning position for a specific Greater London address depends on its history and any designations, which is why we check it at the first visit.
Building over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.
Applications are decided by the local planning authority (your district, borough or unitary council).
Working in Greater London
Towns we cover in Greater London include Bexley, Barking, Sutton, Croydon, Ilford, Enfield, Harrow, Tottenham. London's housing is dominated by Victorian and Edwardian terraces, many with a rear outrigger and a side return, and 1930s semis in the outer boroughs. Conservation areas are common, so the planning check comes first.
Included in a typical project
- Ground and first floor structure, roof tied into the existing roof
- Householder planning application where needed
- Breaking through at both levels, stairs and landing changes where needed
- Building regulations drawings and structural design
- Measured survey, design and planning drawings
- Foundations sized for two floors
Double-storey extension prices in Greater London
For Greater London we adjust our national guide rates by ×1.3, the factor we use for London. Figures include VAT; your written quote after the survey replaces them.
Typical rates in Greater London: £2,020 to £3,900 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m, two floors 24 m² | £49,000 – £59,000 | £56,000 – £73,500 | £71,500 – £94,000 |
| 4 m × 4 m, two floors 32 m² | £64,000 – £77,000 | £74,500 – £98,000 | £95,500 – £125,000 |
| 4 m × 6 m, two floors 48 m² | £96,500 – £115,500 | £112,000 – £147,000 | £143,500 – £187,500 |
Want a range for your exact size? The guide-price tool takes about a minute.
What happens next
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
We visit your Greater London home, measure up, talk through what you want and check the planning position.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
We confirm the build price in writing, based on the approved drawings and the finishes you have chosen.
Build and sign-off
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Double-storey extension questions answered
Who do I contract with for a double-storey extension in Greater London?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Greater London, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Do you cover all of Greater London?
Yes, across the whole of Greater London. Site visits are free and there is no obligation.
Is a two-storey extension cheaper per square metre?
Usually. Our guide range is about £2,020 to £3,900 per m² of new floor area including VAT, compared with £2,280 to £4,420 per m² for single-storey work, because the foundations and roof are shared across two floors.
Do I need a Party Wall Agreement?
If you are in England or Wales and the work involves a shared wall or digging foundations close to a neighbour, the Party Wall etc. Act 1996 applies and notices must be served before work starts. We tell you which notices are needed.
Book a free site visit in Greater London
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.