Flat extensions
London architect guide
Inspiration and ideas
Below we have selected some projects to lend architectural inspiration and design ideas for extending or renovating your property with some flat extensions architect advice and insights.
GOAStudio London residential architecture
George Omalianakis, BA (Hons) B.Arch Pg Dip Environmental Design.
Chartered RIBA architect and ARB registered.
RIBA Conservation Registrant specialism in conservation areas, period and Listed buildings.
Residential expert contributor for magazines including Which? magazine and Ideal Home.
Last reviewed by George Omalianakis for GOAStudio: August 2026
Architect designed garden flat extension Kilburn Brent NW2 – Through views
Hampstead architects flats amalgamation Kitchen views to the garden
Flat extensions GOAStudio architects London architectural and design home guide
Architect designed flat extension Warwick Avenue Westminster W9 Views to the garden
For more advice and information see the following:
Royal Institute of British Architects (RIBA)
- Do I need an architect for my extension or home project?
- Why work with an architect?
- How do architects calculate their fees?
Planning Portal
Flat extensions London architect guide – Design aspirations and key considerations
The architectural elements and design ideas are not what primarily create the essence of ‘home’.
Yet the created spaces accommodate our everyday routines, activities, and little moments that make up our lives.
Extending a flat is not just a box ticking exercise about floor plans, the number of bedrooms, cost per square foot, and Freeholder’s approvals.
Ultimately it is the genuine quality of the spaces around us that are essential for a happy life.
You might find yourself walking in a rather small and modest flat that instantly makes you feel at home, the spaces seem to flow, there is a clear sense of orientation even if you have never set foot in this property before, and if you happen to look carefully you will probably find lots of storage space hidden away from view in the most surprising places.
For such flat extensions architect advice is what you need to help you come up with a space that feels right.
Flat extensions London architect guide – Types and options for your home project
The lack of residential space in London has seen more and more Victorian and Edwardian single family dwellings converted into single or multi-storey flats.
Sometimes these conversions have been successful, but more often that not they have failed to provide accommodation of sufficient standards.
When it comes to possible options when it comes to flat extensions London largely depend on the relationship between the flat and the ground level:
Ground level
Garden flats can have a linear relationship with the garden, (the rear wall is of a straight line) or typically there is an L-shaped layout that opens up the flat both to the rear and side parts of the garden.
Rear and side extensions look to add floor space, create better sightlines to the garden, and improve access to natural light.
They often require a complete redesign of the existing layout of the flat and such extensions look to create opportunities for larger kitchen areas and additional bedrooms.
Middle level
Extensions to such flats are near impossible unless there is a lower level roof area to build on.
Rights to build over such roof areas need to be obtained by the owner of the flat and there are also Freeholder approval issues to consider on top of any other Local Authority permissions required.
Upper level
Roof extensions, including mansard roof extensions when the property is in the right area, add substantial value and floor area to flats.
It is worth remembering that flats do not have Permitted Development Rights under planning, which means that only small dormer extensions are typically allowed by the Council.
What might be possible in design terms will mostly depend on the existing head heights in the loft space and how the staircase can be designed so it maximises the available habitable space while at the same time minimising any disruption to the level below.
For such flat extensions architect advice is required and you need to speak to someone with experience in assessing how best the staircase will comply with the current Building Regulations.
Design development stage
During the design development stage we will get to explore lots of ideas, but you can start the process now by considering answers to questions as such:
- “How long do we plan to live in the property and how is our lifestyle likely to change over this time? What are the chances for a growing family, working from home, or picking up gardening as a hobby one day? Is this flat a place for us to grow into, or is it a stepping stone to our dream property?”
- “What are the top three things we like about the flat, and what are the top three things we want to change as part of extending and re-designing it?”
- “Do we have a specific budget ceiling, and where do we want the money spending to be focussed on? What are the special elements of the design we do not want to compromise and where can we be more flexible within the context of our budget?”
- “What are the provisions of my Lease, or Share of Freehold Agreement, and how do we need to go about securing Freeholder Approval for the building works?”
Request a free Feasibility Review
If you're not quite sure what’s possible, or whether now’s the right time, we can help you make an informed start.
Send over your address, a few photos, and a short outline of what you're hoping to achieve.
We’ll take a look at your site context, planning history, and potential constraints and respond with early advice tailored to your home and circumstances.
Email us with the subject “Feasibility Review” or send us your information through our Contact us page.
Book a Home Consultation
It is the ideal first step if you are planning works to your home or if you are in the middle of purchasing a property in need of renovation.
George will visit the property to understand its character, how you use the space day to day, and offer advice on all relevant design and other matters.
You will come away with a clear sense of your next steps and greater confidence to make informed decisions. The consultation (2hrs, £250 +VAT) is a standalone service with no obligation to proceed.
Visit our Contact us page to book.
Not sure where to start with your renovation or extension?
Read this before you meet an architect, speak to a builder or spend money on drawings.
This free, architect-prepared guide walks you through the 15 essential questions every homeowner should ask before starting a project.
"Should we renovate, extend… or walk away?
15 Questions every London homeowner must ask before starting a project to include homes in Conservation Areas and Listed Buildings."
Whether you're planning a modest rear extension or major alterations to a listed home, it will help you avoid expensive mistakes and give you clarity on what’s possible for your property. Includes guidance on:
Planning approvals. Conservation areas.
Timelines and costs. Appointments you need to make.
Design and sustainability options.
When to press ahead and when to walk away
We provide architectural services for residential projects in the following London Boroughs:
Barnet, Camden, Enfield, Hackney, Hammersmith and Fulham, Haringey, Islington, Kensington and Chelsea, Lambeth, Lewisham, Newham, Tower Hamlets, Waltham Forest, Wandsworth, Westminster
We specialise in
- Greener homes
- Retrofit and energy efficiency for older and traditional buildings
- Conservation areas
- Listed Buildings
- Homeowner architectural services
- Property developments architectural services
GOAStudio London residential architecture limited.
86-90 Paul Street, EC2A 4NE, Hackney
Chestnut Avenue South, E17 9EJ, Waltham Forest
t: 0203 984 3005
