Double-storey extensions in Greenwich
Our design and build teams take on double-storey extensions in Greenwich, from the first measured survey through planning and building control to the finished room.
- Guide price in GreenwichFrom £49,000 inc VAT
- PlanningUsually a householder application
- Build time16–24 weeks on site
- Postcode districtsSE3, SE4, SE8, SE10, SE13
Covering Greenwich
We cover Greenwich and the postcode districts SE3, SE4, SE8, SE10, SE13, SE14. Neighbouring towns we cover include New Cross (1 mile), Blackheath (1 mile), Brockley (1 mile), Catford (2 miles).
For homes towards Kent, Swanley is around 10 miles away. 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
- Measured survey, design and planning drawings
- Building regulations drawings and structural design
- Breaking through at both levels, stairs and landing changes where needed
- Householder planning application where needed
- Foundations sized for two floors
- Ground and first floor structure, roof tied into the existing roof
Will the council need to approve it?
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.
In a conservation area, national park, National Landscape, the Broads or a World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
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).
What should I budget for a double-storey extension in Greenwich?
For Greenwich 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 Greenwich: £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.
Our process, step by step
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
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
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
How long does a double-storey extension take to build in Greenwich?
On site, typically 16 to 24 weeks once approvals are in place. Before that, allow 8–16 weeks design and approvals.
Do I need building regulations approval in Greenwich?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Greenwich, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Does a double-storey extension need planning permission?
Often, yes. In England a two-storey rear extension can be permitted development only if it projects no more than 3 m and sits at least 7 m from the rear boundary, with matching roof pitch and obscure side windows. Side extensions over one storey always need planning permission. We confirm the route at the survey.
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 Greenwich
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.