House extensions Wimbledon SW20 | Vetted & Insured

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

Wimbledon 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 Wimbledon

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 Wimbledon

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 Wimbledon

A well-planned extension adds usable space and light where you need it most, and in Wimbledon'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 Wimbledon

Wimbledon ranges from Victorian and Edwardian terraces to 1920s semis and detached homes, so extensions run from side-returns on the terraces to larger rear and double-storey builds on the bigger plots.

With the average local home selling for around £870,000 over the past year, an extension is a significant investment worth getting right. One thing to plan for early is the local planning picture. Merton Park, Wimbledon Village and Copse Hill are conservation areas where external changes often need permission.

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 Raynes Park, Colliers Wood and Southfields.