Signature Build Properties is a trusted house extension London specialist covering rear extension London, single storey extension London, double storey extension London, side return extension London and kitchen extension London. Furthermore, we manage planning, structural engineering and the full build — fixed price, one company, one point of contact.
As a specialist house extension London builder, we design and build all extension types. In fact, having all trades in-house means faster build programmes, better coordination and a single point of accountability.
A rear extension London extends your ground floor into the back garden — typically used to create a larger kitchen diner or open-plan living space. Furthermore, most rear extensions qualify under permitted development extension London rules.
A single storey extension London is the most common extension type — added to the rear or side of the property at ground floor level. Moreover, single storey extensions often fall under permitted development so planning permission is not required.
A double storey extension London adds space on both ground and first floor — maximising the footprint of your extension investment. As a result, you gain a new kitchen below and a new bedroom or bathroom above for a fraction of the cost per square metre.
A side return extension London fills the narrow alley beside Victorian and Edwardian terraces — creating a much larger open-plan kitchen. In fact, it is one of the best-value extensions for period London properties and typically qualifies under permitted development.
A kitchen extension London creates the open-plan kitchen diner that most London homeowners are looking for — with bifold or sliding doors, roof lights and full glazing. Furthermore, we design the kitchen layout and install it as part of the extension package.
A wrap-around extension London combines a rear and side return extension into one L-shaped build — delivering the maximum possible ground floor space. Moreover, this is the most transformative single-project investment for a London terraced house.
What is house extension cost London 2025? See typical build costs for all extension types below. As your local house extension London specialist, we always provide a written fixed-price contract after a free site survey — no hidden costs.
As a general guide, a single storey rear extension London (4x4m) costs £35,000–£60,000 fully finished. A double storey extension London costs £65,000–£120,000. Nevertheless, all prices are fixed and itemised upfront — the quote we give is the price you pay.
| Extension Type | Typical Cost | Build Time | Notes |
|---|---|---|---|
| Single Storey Rear Extension (3×3m) | £28,000 – £45,000 | 8–12 weeks | Small kitchen or utility extension |
| Single Storey Extension London (4×4m) | £38,000 – £60,000 | 10–16 weeks | Open-plan kitchen diner |
| Single Storey Extension London (5×5m+) | £55,000 – £85,000 | 12–18 weeks | Large open-plan living space |
| Side Return Extension London | £30,000 – £65,000 | 8–14 weeks | Victorian/Edwardian terraces |
| Double Storey Extension London | £65,000 – £120,000 | 16–24 weeks | Ground + first floor |
| Kitchen Extension London | £40,000 – £80,000 | 10–16 weeks | Includes bifolds, roof lights, kitchen |
| Wrap-Around Extension London | £70,000 – £140,000 | 16–24 weeks | Rear + side return combined |
| Planning Application (if required) | £500 – £1,500 | 8–13 weeks | Full planning or LDC |
All prices are indicative for London 2025 and include structure, electrics, plumbing, plastering and decoration. We provide a fixed-price written contract after every free site survey.
From your first call to the keys in your hand — here's how our house extension London team delivers a fully managed, fixed-price build from planning through to final sign-off.
To begin with, our project manager visits your property, assesses the available space, party walls and access. Furthermore, we advise on the best extension type for your property and check permitted development extension London eligibility — completely free.
Following the survey, we produce drawings and check planning requirements. In most cases, a rear extension London or single storey extension London qualifies under permitted development. Where planning is needed, we manage the full application on your behalf.
Once planning is confirmed and the design is agreed, you receive a detailed written fixed-price contract covering every element of the house extension London — from groundworks to decoration. In short, there are no surprises at the end.
Our team then carries out all excavation, foundations, drainage, blockwork and steelwork. Consequently, the structure is built to full building regulations standard with an assigned building control inspector visiting at key stages throughout.
All first fix electrical and plumbing works are carried out before plastering. Once the walls and ceiling are skimmed, our team returns for second fix — sockets, lighting, sanitaryware, kitchen installation, flooring and decoration throughout.
Finally, the building inspector signs off the works and issues your completion certificate. At that point, we carry out a full snagging walk-through with you and issue your written workmanship guarantee. Your new space is ready to enjoy.
Our house extension London price includes everything — from planning and groundworks through to the finished, decorated, signed-off space. In fact, there is nothing left for you to arrange separately.
"Double storey extension on our semi-detached in Ealing — new kitchen diner below and master bedroom with en-suite above. Signature Build managed everything from planning to handover. Finished on time, on budget, and the finish is incredible."
"Side return extension on our Victorian terrace in Hounslow — the kitchen is now twice the size and we have bifold doors into the garden. Signature Build handled the party wall and planning. The result is stunning and the fixed price never changed."
"Single storey rear extension in Hillingdon — permitted development so no planning needed. Signature Build confirmed this on the first visit. Completed in 12 weeks as promised. The open-plan kitchen diner has completely transformed our home."
Our house extension London team will visit your property, check permitted development rights, advise on the best extension type and give you a clear, itemised, fixed-price contract. No obligation — just expert advice and an honest price.
Contact us today to discuss your project and receive a no-obligation quote.
