Garden annexes in London

Covering London

We cover London, including Brent, Islington, Bexley and Barking, and the towns around them.

Homes in London

Terraced houses dominate many London neighbourhoods, so most projects involve shared walls, narrow access and a party wall process. Conservation areas are widespread, and some boroughs have their own mansard and basement guidance.

What is a garden annexe?

A garden annexe is a separate single-storey building in the grounds of a house with its own bedroom, bathroom and kitchenette, used by family members as part of the main household. Unlike a garden office, an annexe that people sleep in normally needs planning permission and full building regulations approval.

Brick, block or timber-frame structure
Heating, hot water and electrics
Accessible design options for older relatives

What is the guide price for a garden annexe in London?

Use these ranges to budget for garden annexes; the survey turns them into a fixed price for the agreed specification.

Garden annexes	Guide price incl. VAT
Standard specification	£2,400 to £2,900 per m²
Good specification	£2,900 to £3,400 per m²
High specification	£3,400 to £3,900 per m²

Do you need permission for a garden annexe in London?

Projects in England go through two separate checks. Planning (or confirmation that the work is permitted development) comes from the district, borough or unitary council, and building regulations approval comes from the council’s building control team or a registered building control approver. Where work touches a shared wall or digs near a neighbour’s foundations, the Party Wall etc. Act 1996 applies.

A self-contained annexe used for sleeping and living normally needs planning permission in England. Permitted development for outbuildings does not cover living accommodation.

What can change the price or programme?

Drainage may need a pump if the garden falls away from the sewer.
A level threshold and wider doors make the annexe suitable for later life.

From first call to completion

Send us the details. Give us a postcode, a rough idea of size and some photos, by phone, form or the guide price tool.
We visit and measure. A surveyor checks the house, the boundaries and the ground, and discusses what is realistic.
Price and paperwork. The design is priced line by line, and we submit the planning and building control applications.
We build it. Work follows an agreed programme, with inspections at each stage and a final sign-off.

Your questions answered

Do I need planning permission for a garden annexe?

Usually yes, because people will sleep in it. Outbuilding permitted development does not cover living accommodation.

How much does a garden annexe cost?

Around £2,400 to £3,900 per square metre including VAT, depending on finish and services.

Can you visit a house in London to quote?

Yes. After a short call we arrange a site visit to measure up and agree what the design needs to do, then send a written price.

Also covering

Learn more about garden annexes, or see every project we cover in London.