Annexe extensions for homes in Chelsea
Our design and build teams take on annexe extensions in Chelsea, from the first measured survey through planning and building control to the finished room.
- Guide price in ChelseaFrom £71,500 inc VAT
- PlanningUsually a householder application
- Build time16–24 weeks on site
- Postcode districtsSW1W, SW1X, SW3, SW5, SW7
Covering Chelsea
Postcode districts we cover around Chelsea include SW1W, SW1X, SW3, SW5, SW7, SW10. Neighbouring towns we cover include Battersea (1 mile), Fulham (1 mile), Notting Hill (2 miles), Shepherds Bush (3 miles).
For homes towards Surrey, East Molesey 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.
Planning and approvals in Chelsea
In England an annexe that stays part of the household and connects to the house is assessed as an extension, but its size usually takes it beyond permitted development, so a householder application describing the ancillary use is the normal route.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
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.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
Applications are decided by the local planning authority (your district, borough or unitary council).
What should I budget for an annexe extension in Chelsea?
Labour and material costs vary across the UK, so for Chelsea we use our London factor (×1.3). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Chelsea: £2,600 to £4,940 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Studio annexe 25 m² | £71,500 – £89,500 | £78,000 – £97,500 | £97,500 – £123,500 |
| One-bedroom annexe 35 m² | £91,000 – £114,000 | £109,000 – £136,500 | £136,500 – £173,000 |
| Larger annexe 45 m² | £117,000 – £146,500 | £140,000 – £175,500 | £175,500 – £222,500 |
Want a range for your exact size? The guide-price tool takes about a minute.
Who an annexe extension suits
- Multi-generational families
- Relatives who need support close by
- Homes with a large side or rear garden
From first visit to completion
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
It starts with a visit to your house to measure, check access and talk through ideas and budget.
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
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Your questions about an annexe extension in Chelsea
Who do I contract with for an annexe extension in Chelsea?
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.
Do you cover all of Chelsea?
Yes. We cover Chelsea and the surrounding parts of Greater London. Site visits are free and there is no obligation.
Do I need building regulations approval in Chelsea?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
How much does an annexe extension cost?
Our guide range is about £2,600 to £4,940 per m² including VAT. A one-bedroom annexe of about 35 m² is typically £109,000 to £136,500 at standard spec in Chelsea.
Will an annexe affect council tax?
It can. Some annexes are assessed separately for council tax, with discounts or exemptions in some cases when occupied by a relative. Check with the Valuation Office Agency (England and Wales), your local assessor (Scotland) or Land & Property Services (Northern Ireland).
Book a free site visit in Chelsea
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.