House Extensions London — Rear, Side, Wrap-Around & Double-Storey
Extensions are the single most effective way to add living space and value to a London home. A well-designed extension transforms how you use your property — opening up ground floors into bright kitchen-dining-living spaces, adding bedrooms, creating home offices, and connecting indoor and outdoor living. We have built over 150 house extensions across London, from compact side return infills on Victorian terraces to large wrap-around builds on detached suburban homes.
Types of Home Extensions
Rear Extensions
The most popular extension type in London. A single-storey rear extension typically adds 15–30 square metres of ground-floor living space, with most homeowners choosing an open-plan kitchen-diner-living layout with bi-fold or sliding doors to the garden. Under permitted development, you can typically extend 3 metres from the original rear wall of a semi-detached or terraced house (4m with prior approval), or 4–8 metres for a detached house.
Side Return Extensions
Side return infills are ideal for Victorian and Edwardian terraced houses with a narrow passage running alongside the kitchen. By building over this passage and often combining with a modest rear extension, we transform cramped galley kitchens into open-plan spaces. The structural glazed roof that connects the side return to the main house floods the new space with natural light.
Wrap-Around Extensions
A wrap-around combines a rear and side return extension into a single L-shaped build, maximising ground-floor space. This type is particularly effective on properties with both a side passage and garden depth to work with. Wrap-around extensions create the largest single-storey footprint increase and are ideal for ambitious open-plan designs.
Double-Storey Extensions
Double-storey extensions add space across two floors — typically a kitchen-dining room at ground level and an additional bedroom or bathroom above. They cost roughly 40–50% more than single-storey builds of the same footprint but deliver nearly double the additional floor area. Almost always require planning permission.
Home Extensions Costs & Pricing
| Type | Size | Price Range |
|---|---|---|
| Side Return Infill | 8–15 sqm | £30,000–£55,000 |
| Single-Storey Rear (3–4m) | 15–25 sqm | £40,000–£75,000 |
| Single-Storey Rear (5–6m) | 25–40 sqm | £65,000–£100,000 |
| Wrap-Around | 25–45 sqm | £60,000–£120,000 |
| Double-Storey Rear | 30–60 sqm | £80,000–£150,000 |
* Prices are indicative for London construction in 2026. Final price depends on specification, finish, and site-specific factors. All our projects are delivered on a fixed-price contract.
Frequently Asked Questions
Do I need planning permission for a house extension in London?
How long does a house extension take to build?
Will an extension add value to my London property?
What is included in your extension quote?
Do you handle party wall agreements?
Can I live in my house during the extension build?
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