Having the Beams team on hand to manage the project and provide extra reassurance on build decisions was incredibly helpful and made the whole experience stress free."
Kerry
London
They have been extremely efficient and reassuring. It was a complex project but they took it all in their stride. They recommended very good contractors who were all punctual, polite and capable."
Andrew
London
All about trust. I felt comfortable with my money, my project, and my home knowing that the outcome would be to my satisfaction or would be made good."
Chris
London
Wandsworth extension builders who design and build
Beams brings design and build together in one place. Our in-house designers plan your extension and a vetted builder delivers it, all under one fixed price and managed end to end, so you get the join-up of design and build without coordinating an architect and a builder separately. Design is optional: bring your own drawings and work straight with a vetted builder if you would rather.
Types of house extension we build
Single-storey rear extension: Extends into the garden, the most popular way to open up a kitchen or living space.
Side return extension: Fills the narrow alley alongside Victorian and Edwardian terraces.
Wraparound extension: A rear and side return combined for the most ground-floor space.
Double-storey extension: Space on two floors, often the best value per square metre.
Kitchen extension: Most extensions are really about the kitchen, which you can specify from our ranges as one project.
What a house extension costs in Wandsworth
Extension cost depends on the type, size and specification, and your borough, so the price is set once the design is agreed. As a broad guide, extensions run from around £2,500 to £5,000 per square metre before VAT and fees, with specification driving where you land. A double-storey costs more in total but often less per square metre, sharing one set of foundations and roof.
As London market estimates, typical all-in project costs run:
Extension type | Typical estimate |
|---|---|
Side return | £55,000 to £120,000 |
Single-storey rear | £80,000 to £150,000 |
Wraparound | £90,000 to £170,000 and up |
Double-storey | £120,000 to £220,000 and up |
These are market estimates, not Beams data or fixed quotes. Your builder confirms a fixed price once the design is agreed. For more detail, see our guide to the cost of a side extension.
Planning permission for extensions in Wandsworth
Many extensions fall under Permitted Development, though this varies by property, and we handle the planning application and building regs for you, covering permitted development, party wall and conservation area considerations where they apply. Getting this right early keeps the project on track.
Our design and build process
1. Design and plan: We visit, talk through what you want, and develop the layout with 3D visuals and material choices.
2. Planning and fixed price: We handle the planning application and building regs, then your builder quotes a fixed price.
3. Build and handover: Your vetted builder delivers it, managed throughout, with milestone payments and a 12-month warranty.
Why an extension is worth it in Wandsworth
A well-planned extension adds usable space and light where you need it most, and in Wandsworth's period terraces a side-return or rear extension can transform a dark galley kitchen into an open-plan family space, adding both liveability and value without the cost and upheaval of moving.
Extending a home in Wandsworth
Wandsworth is heavy side-return territory, with Victorian and Edwardian terraces and the narrow rear alleys that a side-return extension fills to create an open-plan kitchen-diner.
With the average local home selling for around £672,000 over the past year, an extension is a significant investment worth getting right. One thing to plan for early is the local planning picture. Wandsworth has more than 40 conservation areas, including Wandsworth Town and Earlsfield, with Article 4 directions common, so it is worth checking your street early.
Our in-house designers and vetted builders take an extension from first sketch to finished space, side-return, rear, wraparound or double-storey, under one fixed price. We also help homeowners across South London, including neighbouring Earlsfield, Southfields and Putney.
Other services in Wandsworth
We also help Wandsworth homeowners with:
Builders in Wandsworth
Kitchen renovation in Wandsworth
Bathroom renovation in Wandsworth
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