Single-storey extensions in Barnes

Covering Barnes

Our coverage around Barnes (SW13) also includes Chiswick (1 miles to the north) and Putney.

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 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
First-fix and second-fix electrics, plastering and making good

How much should I budget for a single-storey extension?

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

How is a single-storey extension approved in Barnes?

English projects need planning clearance from the local council, building regulations sign-off from building control, and party wall notices where the work is on or near a shared boundary. We prepare and manage all three.

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 can change the price or programme?

Drains under the footprint may need diverting or a build-over agreement with the water company.
Large glazed areas need to meet energy rules, which can shape the size of doors and rooflights.

How does the project run?

Send us the details. Give us a postcode, a rough idea of size and some photos, by phone, form or the guide price tool.
Free site visit. We measure up, look at access, drains and the structure, and talk through options and budget.
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.

What people ask before starting

Can we stay in the house during the build?

Usually yes. We keep the existing house closed off from the works until the knock-through near the end, and agree a temporary kitchen set-up with you if the kitchen is affected.

Will the brick match?

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

Can you visit a house in Barnes 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 single-storey extensions, or see every project we cover in Barnes.