House Extension Architects in London
More space, more light, and a home that works for how you live now. We design house extensions across London and the South East, and take them from first sketch through planning permission, building regulations and structural design, all from one studio in Battersea.
Free 45-minute consultation
3 concept designs with our fixed-fee Feasibility Package
Planning, building regs and structural calculations under one roof
Types of house extension we design
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Rear extensions
The most popular way to add a larger kitchen, dining or living space that opens onto the garden. Single storey rear extensions can often be built under permitted development; larger ones may need planning permission or prior approval.
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Side return extensions
Common on Victorian and Edwardian terraces, a side return extension fills the narrow passage beside the back of the house to create a wide, light-filled kitchen.
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Wraparound extensions
Combining a side return and a rear extension into one L-shaped space for the biggest change to the ground floor.
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Kitchen extensions
Designed around how you cook, eat and gather, with glazing, rooflights and layout planned together. "A fantastic design for our kitchen extension." Emily
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Double storey extensions
Adds space downstairs and a bedroom or bathroom upstairs. These almost always need planning permission, and we prepare the full application.
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Loft and basement additions
If you're extending in more than one direction, we can design the whole scheme together. →
Why homeowners choose ADO
Extension design that's ready to build, not just ready for planning
Many extension projects stall between the drawings and the build. We avoid that by designing, drawing and engineering your extension as one joined-up package.
One team from concept to completion Design, planning drawings, building regulations drawings and structural calculations are handled together, so nothing is lost between consultants.
Drawings in 2–3 weeks Once the design is agreed, technical drawings are typically ready within 2–3 weeks.
See it before you build it Virtual reality walkthroughs let you stand in your new kitchen or living space before work starts.
Clear costs from the start Our Feasibility Package includes a detailed cost breakdown, so you can test ideas against your budget early.
Recent London extensions
Quarrendon Street
Fulham, London
Oxshott Way
Oxshott, Surrey
Elmwood road
Chiswick, London
Cassidy Road
Fulham, London
Waldemer Ave
Ealing, London
Richmond Park Road
Kingston, London
OUR EXPERTISE
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House Extension Architects
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Loft Conversion Architects
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Kitchen Extension Architects
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New Build Architects
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House Renovation
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Basement Conversion
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Rear Extensions
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Flat Conversion
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Multi-Unit
Our Architectural Approach
From the first conversation to the day you move back in, Architectural Designs Office handles every stage of your extension, loft or new build from our studio in Battersea. Design, planning, building regulations and structural engineering sit with one team, so your project moves forward without gaps between consultants.
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Free 45-minute meeting
We start by listening. Tell us how you live, what isn’t working and what you’d like to spend, and we’ll talk through what’s realistic for your home, your budget and your council.
You get: honest early advice and a clear next step.
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Concepts and a cost breakdown
Our fixed-fee Feasibility Package explores three design options for your home, each with a detailed cost breakdown, so you can compare ideas against your budget before committing to one.
You get: concept designs and costs to decide with confidence.
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Accurate measured drawings
We carry out a full measured survey of your property and its surroundings. Every drawing that follows is built on accurate dimensions, which avoids surprises later.
You get: existing plans, elevations and sections.
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3D models and VR walkthroughs
Step inside your new space before anything is built. Our virtual reality walkthroughs and 3D views help you test layouts, light and finishes, and show planners exactly what’s proposed.
You get: a design you’ve already experienced, not just imagined.
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Application and council liaison
We prepare your planning drawings and submit the application, or a lawful development certificate if your project falls under permitted development. We then deal with the council on your behalf until a decision is made.
You get: a complete application and one point of contact throughout.
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Building regulations and structural calculations
Detailed technical drawings and in-house structural calculations are produced together, typically within 2–3 weeks of the design being agreed. Drainage, structure and key details are resolved before builders price the job.
You get: a build-ready package for building control and contractors.
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Choosing the right builder
We help you prepare tender documents, invite suitable contractors and compare their quotes line by line, so you choose on value and quality, not just the lowest price.
You get: comparable quotes and a recommended contractor.
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Project management to completion
Once work starts, we can manage the project through to handover, keeping an eye on budget, quality and programme, and answering builders’ questions as they come up.
You get: a finished home that matches the design.
Planning permission and permitted development
Do you need planning permission for a house extension?
Not always. Many single storey extensions can be built under permitted development (PD), which means no planning application is needed, as long as the extension stays within set limits on depth, height, width and materials.
As a general guide for houses (not flats):
Single storey rear extensions: up to 3 metres deep on a terraced or semi-detached house, or 4 metres on a detached house, under standard PD.
Larger rear extensions: up to 6 or 8 metres may be possible through the prior approval process, where neighbours are consulted.
Side extensions: single storey, no wider than half the width of the original house.
Exceptions: flats and maisonettes don't have PD rights; conservation areas, listed buildings and Article 4 areas have stricter rules. Much of South-West London falls into these.
We check your property's status at the start, and advise whether a planning application, prior approval or a lawful development certificate is the right route.
Areas we cover
Extension architects across South-West London and beyond
Based at 7A Lavender Hill, Battersea, we work across:
Battersea · Wandsworth · Clapham · Balham · Fulham · Putney · Chiswick · Ealing · Richmond · Kingston · Wimbledon · and Surrey, including Oxshott
Know your council? We work with local planning teams across London and the South East.
What Makes Us Unique
SIMPLICITY
SUSTAINABILITY
TECHNOLOGY
Loft Conversion Architecture
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Home Extension Drawings
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Planning Permission Support
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Structural Steel Calculations
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Building Regulations Drawings
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Internal Modifications
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Chimney Removals
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Loft Conversion Architecture • Home Extension Drawings • Planning Permission Support • Structural Steel Calculations • Building Regulations Drawings • Internal Modifications • Chimney Removals •
Looking to purchase a property but want to explore your options first?
Our Concept Feasibility Package has been designed with you in mind! This package is a one off set fee, which involves an initial consultation to discuss your brief and the property, 3 x concept designs and a detailed cost breakdown to show you how much your ideal project would cost, or what you can achieve with your budget!
Concept Feasibility Package
Visualise your home
See your new space come to life before the bricks are laid with virtual reality walkthroughs. Make informed choices, explore every corner and enjoy that excited feeling.
Plan your home
Leave the details to us as we manage your project from start to finish; monitoring the budget, handling planning permission and liaising with contractors.
Enjoy your home
Step into your new space and experience a sense of joy that stays with you, day after day. And we’ll keep checking in to make sure you’re happy.
Let's create your home's next chapter
Fill in the form below with your project details and we'll respond in 1-2 days.