Single-Storey Extensions
Create a larger kitchen, dining room, family room or open-plan living area across the ground floor.
Ideal for kitchens and living spaceLondon design & build extension specialists
Design & Build Extensions London
Transform your London home with one expert team managing the full extension journey: design, planning, building regulations, project management and construction.
1 Teamdesign, planning and build
Londonlocal extension specialists
Freeinitial consultation
Clearfixed pricing approach
One-stop extension service
A complete design-and-build service for London homes
Choosing a design and build extension company means you do not need to manage separate architects, builders, trades and project managers.
We bring the full process together, from the first design idea through to planning guidance, construction and final handover. This gives you a smoother route, better communication and a clearer understanding of cost before work begins.
Whether you want a larger kitchen, a rear extension, a side return, a wraparound layout or a double-storey home extension, we design the project around your property, your budget and the way your family lives.
- Bespoke layouts for Victorian terraces, semi-detached houses and detached homes
- Design advice to maximise space, light, storage and flow
- Planning permission, permitted development and building regulation support
- Dedicated project management from survey to completion
Our design & build extension services
Every London property is different, so we recommend the right extension type, design route and build approach for your home.
Double-Storey Extensions
Add space on two floors, often combining a larger ground floor with bedrooms or bathrooms above.
Maximum extra floor areaSide Return & Rear Extensions
Use unused side or rear space to improve narrow London homes and bring in more natural light.
Popular for terracesWraparound Extensions
Combine side and rear extension space to completely transform the ground floor layout.
Best for major transformationsSimple managed process
The design & build process
Our process keeps everything clear, coordinated and professionally managed, so you always know what happens next.
Consultation & home survey
We discuss your goals, inspect your property and advise on the most suitable design and build route.
Design, feasibility & planning
We develop the layout, advise on planning permission or permitted development, and coordinate drawings and structural requirements.
Construction & project management
Our team manages trades, communication, scheduling, quality control and site progress from start to finish.
Finishing, snagging & handover
We complete the final details, checks and handover so your new extension is ready to use.
Planning permission and building regulations handled properly
London extensions often need careful planning because property type, conservation areas, party wall matters, drainage, structural work and local borough rules can affect what is possible.
- We check whether your extension may fall under permitted development or needs planning permission.
- We help coordinate drawings, structural calculations and building regulation requirements.
- We advise on party wall considerations for terraced and semi-detached homes.
- We keep the process clear so you are not left dealing with confusing paperwork alone.
Why choose our London design and build team?
You need more than a builder. You need a coordinated extension company that understands design, planning, construction and the realities of London homes.
One company, one route
Design, planning, project management and build are coordinated together, reducing confusion and delays.
London property knowledge
We design around terraces, semi-detached houses, compact plots, older buildings and local planning challenges.
Clear pricing
You receive practical advice and a clear quotation before committing to the construction stage.
Better communication
A managed process means fewer handovers between separate companies and more accountability throughout.
Project management
Scheduling, trades, site coordination and quality checks are handled by one organised team.
Built around your lifestyle
We design extensions around how you cook, relax, work, entertain and use your home every day.
Design & build extension costs in London
Costs depend on the size, extension type, structure, glazing, kitchen requirements, bathrooms, finishes, access and planning route. A full design-and-build service gives you clearer cost control because the design is developed with buildability in mind.
Smaller single-storey projects
Suitable for simpler rear or side extensions with standard finishes and straightforward structure.
Often from approx. £35k+Larger kitchen extensions
Popular for open-plan kitchen, dining and family spaces with rooflights, glazing and better finishes.
Commonly £50k–£75k+Double-storey extensions
More complex projects that add space across two floors and normally require more planning and structural work.
Higher investmentClear fixed quotation
After reviewing your home, we provide a tailored quote based on your property, design, specification and scope.
Free consultationFrequently asked questions
Helpful answers before you start your London design and build extension.
What is a design and build extension?
A design and build extension means one company manages the architectural design, planning support, construction and project management. You get one coordinated route instead of using separate architects and builders.
How much does a design and build extension cost in London?
Costs vary by size, specification and extension type. Smaller single-storey projects may start from around £35,000, while larger or more complex extensions cost more. We provide a tailored quote after reviewing your home.
How long does a house extension take?
A typical single-storey extension may take around 10–14 weeks on site, while the full process including design, planning and approvals can take several months. Larger projects can take longer.
Do I need planning permission?
Some single-storey extensions may fall under permitted development, but double-storey extensions, conservation areas and larger designs often need planning permission. We check the correct route before work starts.
Why use a design and build company instead of a separate architect and builder?
A design and build company gives you one point of contact, better coordination, improved cost control and a smoother handover from design into construction.
Can you manage the full project?
Yes. We can support design, planning, building regulations, structural coordination, construction, project management and final handover.
Start your design & build extension with confidence
Tell us what you want to create and we will advise on the best next step, from initial design and planning through to construction.
- Free consultation with no obligation
- Design, planning and build under one roof
- Guidance on building regulations and structural requirements
- Dedicated project management from start to finish
1 Expert Team
London Focus
Free Initial Review
Request Your Free Quote
Tell us about your project and we will come back to you with the best next step.
No pressure. No obligation. We reply within 1 working day.
Ready to plan your London home extension?
Speak with our team about your design and build extension and get clear guidance on design, planning, cost and construction.