— Service Details
House Extensions London
At New Build Contractors, we design and build bespoke house extensions that unlock the full potential of London homes. From light-filled kitchen extensions with skylights and bi-fold doors to practical rear or wraparound extensions that change the way you live, we bring your vision to life with precision and care.
More Space, Value & Comfort in Your Home
We know that for many families in London, moving isn’t always the answer. High property prices, limited housing stock and the desire to stay in a much-loved area make extending your current home a smarter, more sustainable option. With a well-planned extension, you can have the extra space you need without the stress and cost of moving.
A well-designed extension not only enhances your lifestyle but also adds long-term value to your property. Whether you’re creating a larger open-plan kitchen for family gatherings, a dedicated home office or simply more breathing room, our team of architects, engineers, and skilled builders will guide you through every stage, from initial design to completion.
With years of experience working on London’s diverse property styles, from Victorian terraces and Edwardian homes to modern townhouses and detached properties, we know how to blend new spaces with the character of your home. Every detail is carefully considered, ensuring your extension is both functional and beautiful.
Why Choose a House Extension in London?
A house extension is one of the best investments you can make in your London home. Here’s why more and more Londoners are choosing to extend rather than move:
Space for modern living – Whether you’re having a new baby, working from home, or need more storage and flexibility, an extension gives you room to breathe.
Stay in the area you love – Many of our clients live in places they don’t want to leave. By extending, you can stay close to friends, schools and transport links.
Cheaper than moving – Factoring in stamp duty, solicitor fees, and the rising cost of property in London, extending is often much more cost-effective than buying a bigger one.
Increase your home’s value – A well-designed extension can add significant value to your property, making it a worthwhile investment that pays off now and in the future.
Designed for you – Unlike moving into a new home, an extension is tailored to suit how you want to live. Open-plan kitchens, garden-facing dining rooms, or quiet study spaces can all be created to suit your needs.
— Process
Our Extension Process - From Idea to Completion
We know taking on a building project can be overwhelming, so we’ve broken it down into a simple, 4-step process
Consultation
We meet you at your home to discuss your ideas, take measurements and talk through options. Our in-house architects create detailed drawings that meet your needs and maximise the use of space, light, and style.
01
Planning and Quote
We handle planning applications as necessary, advise on permitted development rights, and ensure designs comply with building regulations. Once designs are approved, we provide a fixed, detailed quote so you know exactly what’s included, no hidden extras.
02
Construction and Management
Our experienced builders carry out the work, and regular site visits ensure that high standards are maintained throughout. Every client has a project manager who oversees the build, keeps you updated and ensures the work is completed on time and to budget.
03
Handover and After-care
On completion, we provide all certificates and paperwork, and your extension comes with a 10-year structural warranty for your peace of mind.
04
Types of House Extensions We Deliver
Every property and every family is unique, which is why we offer a wide range of extensions.
Rear Extensions
One of the most popular in London, a rear extension uses garden space to add to the back of your property. Perfect for open-plan kitchens, larger living areas or dining spaces that flow directly onto your garden through sliding or bi-fold doors.
Side Return Extensions
Ideal for London’s Victorian and Edwardian terraces, side return extensions turn the often unused alleyway at the side of the property into valuable living space. By opening up the back of the house, you can create a more expansive kitchen, a brighter dining area, and a more fluid ground-floor layout.
Wraparound Extensions
For maximum impact, a wraparound combines both a rear and side return extension, creating an L-shape. This often results in a light-filled living space with multiple zones for cooking, dining and relaxing.
Kitchen Extensions
The kitchen is the heart of the home, and a bespoke kitchen extension can change the way you use your space. From large islands and breakfast bars to floor-to-ceiling glazing, we design kitchens that are practical for family life and perfect for entertaining.
Double-Storey Extensions
Do you need more bedrooms, bathrooms, or office space upstairs as well as downstairs? A two-storey extension is the answer. These extensions add substantial extra square footage and can increase your property’s value.
Flat or Pitched Roof Extensions
The choice between flat and pitched roofs allows us to match your home’s style and maximise natural light. Flat roofs with skylights are popular for modern builds, and pitched roofs are often chosen to blend with period homes.
| Extension Type | Description | Image |
|---|---|---|
| Rear Extension | Add depth to your home with a rear extension, perfect for kitchen-diners opening onto the garden. |  |
| Side Return Extension | Make use of the narrow side alley in London terraces to expand your kitchen or living space. |  |
| Wraparound Extension | Combine rear and side extensions to create a large, open-plan living area filled with light. |  |
| Two-Storey Extension | Extend both ground and first floor, adding extra bedrooms and family space at once. |  |
| Kitchen Extension | Create a modern, light-filled kitchen with skylights, sliding doors, and space for entertaining. |  |
| Flat Roof Extension | A cost-effective way to expand, with options for skylights and clean modern finishes. |  |
| Upward Extension | Build upwards to add bedrooms or office space when ground-level expansion isn’t possible. |  |
At New Build Contractors, we’ve spent years working alongside families, developers, and homeowners to create luxury homes that feel personal, functional, and built to last. Whether you're planning a high-spec new build or looking to upgrade your current home, we offer honest guidance, practical solutions, and hands-on support from day one.
Cost of a House Extension in London
One of the first questions most people ask is, “How much will my extension cost?” The answer is that it depends on many factors, including the size of the build, the complexity of the design, and the level of finishes you choose. No two projects are ever the same, but here are some rough guidelines.
London House Extension Costs
Rear or side return extensions – from £40,000+
For bigger kitchens, dining areas or extra living space.Wraparound extensions – from £70,000+
A more significant transformation that combines both rear and side elements, often resulting in open-plan living areas.Double-storey extensions – from £90,000+
Big builds that go up and down, adding real space and value to your home.
These are just rough estimates. Your final cost will depend not only on size but also on design complexity, structural requirements, and the finishes you choose — including flooring, glazing, bespoke joinery, and more.
What Affects the Cost of the Extension
Several things to consider:
Property type and location – Older properties often require more extensive structural work, while conservation areas necessitate specific design details.
Materials and finishes – Standard finishes or premium options, such as aluminium bi-folds, bespoke cabinetry, or high-performance glazing.
Structural complexity – Double-storey builds, basements or homes on restricted plots require more engineering.
Planning and permissions – Some boroughs require additional approvals or specialist input, which can impact timelines and costs.
Pricing and Value
At New Build Contractors, we believe in transparency. Once we’ve surveyed and agreed on the design, you’ll receive a detailed breakdown of costs, so you know exactly what’s included—no hidden extras or surprise add-ons.
While extensions are a big investment, they are also one of the best ways to add long-term value to your London home. In many cases, the extra space and modern design add more to your property’s value than the cost of the build itself.
Moving vs Extending – What’s More Cost-Effective in London?
For many families, it’s a choice between moving into a bigger property or extending the home they already love. Here’s how the two options compare in London:
| Expense | Extending Your Home | Buying a Bigger Home in London |
|---|---|---|
| Upfront Costs | From £40,000–£120,000+ depending on extension type | Often £150,000–£300,000+ more for a larger property |
| Stamp Duty | £0 (not applicable) | £25,000–£50,000+ depending on purchase price |
| Legal & Moving Fees | Minimal (planning & design only) | £5,000–£10,000+ for solicitors, removals, surveys |
| Disruption | Works carried out while you remain in your home | Full relocation, packing, moving schools, new area |
| Added Value | Strong ROI – well-designed extensions can add 15–25%+ to property value | Limited — future value tied to local market conditions |
| Emotional Factor | Stay in the home and area you love | Leave behind neighbours, schools, and community |
Moving might seem like the quick fix for more space, but the costs add up quickly, and you often compromise on location. A house extension, on the other hand, lets you stay in the area you love and create a bespoke space that works for your lifestyle.
At New Build Contractors, we make it simple and transparent, so you know the costs from the start, allowing you to plan with confidence.
A Real-World Example – Extending vs Moving
A family living in a Victorian terrace in Wimbledon loved their home and the area, but were running out of space as the kids grew up.
Option 1: Moving
They considered buying a bigger house nearby. Similar four-bedroom properties in the area were selling for £1.1m–£1.2m — £250,000 more than their current home. Additionally, they would have to pay £45,000 in stamp duty and £8,000 in moving and legal fees.Option 2: Extending
Instead, they opted for a wraparound kitchen extension with skylights and bi-fold doors that open onto the garden. The project cost around £75,000. Not only did they get the open-plan kitchen-diner they wanted, but also an extra living room and more light on the ground floor.The Result
Local agents estimated that the extension added £150,000–£200,000 to the property’s value. In other words, they got the space they needed, increased the value of their home and avoided the stress and costs of moving — all while staying in the area they love.
What our Clients Have to Say About Us
Not always. Many single-storey extensions are allowed under permitted development rights, so you may not need formal planning permission if your project meets certain conditions. These are typically determined by size, height, and how far the extension extends out from the existing house. Single-storey extensions, being on the whole more compact and straightforward, are also usually more likely to be considered permitted development than their larger counterparts. The only way to be certain is to consult a local professional who can confirm whether you need permission for your extension.
You also cannot extend your home past a specific size under permitted development rights. For single-storey extensions, the maximum depth is usually 3m for attached homes and 4m for detached (it’s possible this can be doubled with prior approval). Check with your local planning authority before you begin any work.
Planning permission is the formal consent granted by your local authority to a proposed build. So-called permitted development (PDR) enables some extensions to be built without requiring the agreement, but only if strict size, height and design restrictions are observed.
Yes. A well-thought-out extension can provide a significant amount of extra space and add value to your home when it comes to selling. Kitchen extensions, rear extensions and two-storey builds tend to deliver the best return on investment.
In most cases, yes. Extensions provide more floor space, offer better practicality for homes, and are very popular with buyers. Among all those endless extensions, kitchens and open-plan ones are among the most popular, and often give one of the best returns for homeowners.
Listed buildings and those situated in conservation areas are not covered by permitted development rights. You will almost always need to obtain full planning permission, as well as other consents, before carrying out any work.
The Next Space is Yours
Let’s Design What’s Next
— Address
71-75 Shelton Street Covent Garden London WC2H 9JQ
— Hours
Mon-Fri: 9 AM to 5 PM
Sun: Closed