Single-storey extensions in London

Covering London

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

Homes in London

Much of London’s housing is Victorian and Edwardian terraces, which is why side return extensions, rear dormers and mansards are so common. Many streets are in conservation areas, and several boroughs use Article 4 directions that remove some permitted development rights.

What is a single-storey extension?

We design the extension around how you use the house: where the light comes from, how the new room joins the old one, and what happens to the drains and the garden. The structure is built in brick or block to match the house, finished with a flat roof and lantern or a pitched roof, then insulated, plastered and handed back ready to decorate.

Planning or lawful development certificate where needed
Building control application and inspections
Foundations, drainage and structural steel

How much does a single-storey extension cost in London?

Use these ranges to budget for single-storey extensions; the survey turns them into a fixed price for the agreed specification.

Single-storey extensions	Guide price incl. VAT
Standard specification	£2,600 to £3,000 per m²
Good specification	£3,000 to £3,500 per m²
High specification	£3,500 to £4,000 per m²

What approvals does a single-storey extension need in England?

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.

In England a single-storey rear extension can often go ahead under permitted development: up to 3 m deep on an attached house or 4 m on a detached one, no higher than 4 m, with eaves no higher than 3 m within 2 m of a boundary. Deeper extensions, up to 6 m or 8 m, need prior approval from the council first.

What should I think about before starting?

Drains under the footprint may need diverting or a build-over agreement with the water company.
Building on or near a shared boundary usually means serving a party wall notice in England and Wales.

What are the steps?

Send us the details. Give us a postcode, a rough idea of size and some photos, by phone, form or the guide price tool.
Survey at your house. We look at the existing structure, services and access, and agree what the design needs to achieve.
Drawings, approvals, written quote. We prepare the design, apply for the approvals it needs, and give you a fixed price in writing.
We build it. Work follows an agreed programme, with inspections at each stage and a final sign-off.

What people ask before starting

Do you need to dig up the drains?

Sometimes. If a public sewer runs under the extension, the water company has to agree a build-over or a diversion. We check this at survey stage.

Will the brick match?

We source the closest available match for colour, size and texture and agree a sample panel with you before laying.

Do you work in London?

Yes. London is within our coverage for single-storey extensions, along with nearby Brent and Islington.

Also covering

Learn more about single-storey extensions, or see every project we cover in London.