Rear Extensions Designed for the way you actually live
We design and build rear extensions across London that transform how your home works. From permitted development schemes to ambitious open-plan living spaces, every project is led by our in-house architects and delivered by our own construction team.
The most popular way to transform a London home
A rear extension is the most popular type of house extension in London because it works with almost every property type. It can open up a narrow kitchen, create a spacious dining area, or establish a seamless indoor-outdoor connection with your garden through large glazed openings.
The right approach depends on your property and how you want to live. A simple rear extension can add depth to your ground floor, while a wraparound design can combine rear and side return space for a far more ambitious transformation.
Our Role in Your Project
From initial survey through to detailed construction drawings, we provide complete architectural support.
Choose a full design-and-build package or select specific stages depending on your project. Speak to our team
What is a rear extension in London?
A rear extension adds new living space at ground floor level by extending the back of your home into the garden. It is the most common and cost-effective way to increase usable floor area, allowing homeowners to create an open-plan kitchen and dining space, enlarge a living room, add a utility area, or simply improve the layout and flow of the ground floor.
Rear extensions work particularly well on terraced and semi-detached properties where extending to the rear is often the only practical option. Under permitted development rights, you can typically extend up to 3 metres from the original rear wall of a terraced or semi-detached house, or up to 4 metres for a detached property, without needing planning permission. Larger rear extensions of up to 6 metres (or 8 metres for detached homes) may be possible through the prior approval process.
Design Options
Whether you prefer a traditional design matching the character of your existing home, or a contemporary approach using contrasting materials such as glazing, timber cladding, or aluminium frames, we tailor every rear extension to your property and brief.
Rear extension projects in London
Why choose a rear extension in London?
A rear house extension is one of the most effective ways to transform how your home functions day to day. It focuses on improving the ground floor, the part of the house where families spend most of their time, by extending into the garden and creating space that feels open, connected, and full of natural light.
For terraced and semi-detached homes across London, existing ground floor layouts can feel narrow, segmented, or disconnected from the garden. A well-designed rear extension opens up the back of the house, improves circulation, and establishes a genuine relationship between your kitchen, dining, and living areas and your outdoor space.
Rear extensions are typically less structurally complex and more straightforward to construct than double-storey or basement projects. Many fall under permitted development, which means no planning application is needed.
- Increase usable living space at ground floor level
- Create open-plan kitchen, dining, and living areas
- Enhance natural light and garden access through glazing
- Add strong market appeal and long-term resale value
For many London homeowners, a rear extension represents the ideal balance between investment, practicality, and long-term value. It is the single most popular home improvement project in the capital for good reason.
Our Featured Works
How we design rear extensions at Salstan Architecture
Our approach to rear extensions is centred on creating ground floor space that feels seamless, bright, and genuinely practical for everyday living. We begin by understanding how you use your home now and what you want the extension to achieve, whether that is a larger open-plan kitchen, a better connection to the garden, or simply more room for a growing family.
We design every rear extension with natural light and proportion in mind. This includes careful consideration of glazing, roof form, and ceiling height to avoid dark or compressed areas. We ensure the extension integrates with the existing property through appropriate scale, materials, and detailing, so the result feels like a natural part of the home rather than a bolt-on addition.
From planning and Building Regulations through to site delivery, we keep the project coordinated and controlled, with clear sequencing, quality checks at key stages, and consistent communication throughout.
Our process explained in six easy steps
What our clients say about us
Rear Extension Design Pricing
Transparent design fees for your rear extension project. No hourly rates, no surprises.
- Full 3D measured survey with Lidar
- 3D architectural drawings
- Unlimited design changes per scope
- Planning submission and liaison
- Full support and expert advice
- Full building regulation drawings
- Technical specifications
- Expert building control advice
- Combined with structural package
- Full structural calculations
- Structural design drawings
- By chartered structural engineers
- Price varies by complexity
All prices exclude VAT. Local authority planning fees not included. View full pricing details
Rear Extension Build Pricing
Indicative construction costs for our design and build rear extension packages. All pricing is subject to a detailed site survey, exact scope of works and your specific property requirements.
3 Metre Rear Extension
Single storey rear extension under permitted development rights
Final quote confirmed after site survey
- Detailed architectural design
- Lawful Development Certificate application
- Full project management
- Shell and core construction
- Construction up to second fix
- Full structural design calculations package
- Full control of all paperwork including Building Control, Thames Water submissions and more
6 Metre Rear Extension
Larger rear extension requiring prior approval or full planning permission
Final quote confirmed after site survey
- Detailed architectural design
- Prior approval or planning application
- Full project management
- Shell and core construction
- Construction up to second fix
- Full structural design calculations package
- Full control of all paperwork including Building Control, Thames Water submissions and more
Prices shown are indicative starting points based on typical projects of this size. A genuine fixed build cost can only be provided once planning permission is granted and detailed construction designs are complete. This is because the approved design is what truly determines the scope, specification and cost of construction. We take this approach so that every quote we provide is accurate and fully costed to your specific project, rather than an inflated estimate built around unknowns. Learn more about our construction services or speak to our team
Accreditations & Education
Trusted Experience Across Architecture,
Engineering & Construction
Our team’s background combines architectural design, structural engineering and construction delivery.
Civil Engineering
Institution of Civil Engineers
Structural Engineering
The Institution of Structural Engineers
City University London
Academic excellence in the built environment
Loughborough University
Academic excellence in design & innovation
UCL
Academic excellence in architecture & engineering
Civil Engineering
Institution of Civil Engineers
Structural Engineering
The Institution of Structural Engineers
City University London
Academic excellence in the built environment
Loughborough University
Academic excellence in design & innovation
UCL
Academic excellence in architecture & engineering
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Frequently Asked Questions
In many cases, no. A rear extension can often be built under permitted development rights, which means you may not need a full planning application. However, this depends on a number of factors including the size of the extension, how far it projects from the original rear wall, the height of the structure, and whether any previous extensions or outbuildings have already used up your permitted development allowance. In conservation areas or with listed buildings, additional restrictions apply. We assess each case at the start of the project to give you clear, site-specific guidance.
Design and planning typically take around 2–3 months, depending on the complexity of the project and whether a full planning application is required. Build times for a rear extension usually range from 8 to 16 weeks once on site, though this varies based on the scale of the works, structural requirements, and internal fit-out. We provide a clear programme from the outset so you know what to expect at every stage.
Under permitted development, a single storey rear extension can project up to 3 metres from the original rear wall for an attached property, or up to 4 metres for a detached house. Through a prior approval process (known as a Larger Home Extension), these limits can increase to 6 metres and 8 metres respectively. Extensions beyond these limits, or those that do not meet other permitted development criteria, will require a full planning application. We review your specific site conditions and advise on the best route forward.
The cost of a rear extension depends on several factors, including the footprint, materials, structural complexity, and internal specification. In London, rear extensions typically range from around £2,000 to £3,500 per square metre for construction, with design and planning fees on top. We offer early budget guidance based on your site and goals so you can make informed decisions before committing. Every project is different, so an accurate estimate starts with a clear brief and a site survey.
Yes. A well-designed rear extension is one of the most effective ways to add both space and value to a London property. By improving the ground floor layout — typically creating a larger kitchen-diner or open-plan living area with a strong connection to the garden — a rear extension can significantly increase your home’s market appeal and overall value. The key is ensuring the design is practical, well-proportioned, and finished to a high standard.
Who We Work With
