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Reimagining the spaces beneath your home.
At Armstrong Simmonds Architects, we specialise in transforming underused basement levels into light-filled, elegant living areas. Whether you’re seeking to expand your home with an extra bedroom, family lounge, cinema room, or a spacious open-plan kitchen, our team brings vision, technical precision, and experience to every project in basement conversion London and basement extensions London. We understand that basements in London are more than just additional space — they are an opportunity to create something truly bespoke, with direct access to gardens, innovative glazing, and clever use of natural light.
Aside from providing you with a beautiful design, your architect needs to navigate complex
planning and building laws that regulate the construction industry. Therefore, appointing a
practice with the right amount of experience is the key to a smooth project delivery. Although
not essential, appointing a RIBA chartered practice is also an important factor to consider.
Being RIBA Chartered means that the practice must adhere to a code of conduct of
professionalism and ethics which ensure quality control within the Architectural industry. The
experience of the practice within London is another important factor to consider, particularly,
as each borough has different modes of operation which can influence the design process.
Whilst the National Planning Policy Framework (NPPF) provides the backbone for planning
policy, each individual borough will have its own set of policy and guidance. A particular
challenge within the borough of London is the planning process for basement design. For
such a complex undertaking, stringent planning requirements must be met in the form of
traffic reports, geology surveys and more. Another challenge is the added complexity of
working with historic buildings. If your building is within a conservation area, a designated
building of interest, or a listed building, any work to that building or surrounding area will be
subject to strict requirements that are typically more rigorous than standard planning
requirements. London Architects and designers must ensure their clients are advised
appropriately on the process and that suitable consultants are appointed to conduct the
necessary work.
Our portfolio includes a wide range of residential projects across London, including basement conversions, loft conversions, extensions, and full house renovations. Each project is developed with a focus on spatial clarity, natural light, and long-term usability.
Maximise space without expanding upwards
In many parts of Central and South West London, extending below ground is often the most effective way to increase square footage without altering the external footprint of your home. Whether your property is listed, in a conservation area, or faces planning constraints, a basement can provide valuable space while preserving the architectural character of your house. A London basement extension or basement conversions London can unlock the potential of your property and add significant value.
Our basement designs focus on creating liveable spaces that feel anything but underground. We prioritise the intelligent use of lightwells, internal courtyards, and full-height glazing to ensure rooms are bright and connected to the outdoors. These lower ground areas often open directly onto garden terraces, creating a seamless indoor-outdoor living experience. As experienced basement architects and a leading architect studio, we understand how to make the most of natural light and innovative design for every basement extension London project.
As a RIBA Chartered Practice based in Battersea, we guide you through the entire process:
Assessing site potential, existing structure and planning context.
Developing ideas tailored to your vision and lifestyle, drawing on our expertise in architect for basement design.
Liaising with local councils, navigating permissions and regulations.
Producing detailed construction drawings with structural coordination.
Recommending trusted local builders.
Regular visits, contract administration, and quality control during construction.
We work across all RIBA stages, delivering fully integrated basement projects that are functional, stylish, and highly tailored through our comprehensive architectural services. Our approach as a basement design studio and architect basement design experts ensures a smooth and transparent process.
With years of experience working in some of London’s most desirable boroughs, including Kensington, Chelsea, Clapham, Wandsworth and Fulham, we understand the local planning climate and technical challenges of basement construction. From complex site conditions to listed properties and tight urban plots — our team brings practical knowledge and design creativity to every brief. We provide bespoke solutions for London basement conversion and London basement extensions, tailored to each client’s needs.
We are glad we found Armstrong Simmonds Architects to help us on our first project. We had bought a run-down terraced house near Clapham Common with the goal of extending and refurbing to increase value. John initially impressed us by first listening carefully to what we wanted to do, then showing us creative ways to achieve the results and finish we were looking for.
Safe to say we certainly have managed that and both John and Alan have been instrumental in doing so. The guidance and consideration at every step have exceeded our expectations and Alan’s attention to detail during the build has been critical for the high standards we have set for this project.
They have provided us with a service which reflects every stage of the design and build. Starting with the initial drawings, schedule of works, tendering and interior design. We also employed ASA for Contract Administration to be the key middle-man between us and the builder, which they were happy to help.
We are now underway with our second project with ASA and they have been able to deliver the final drawings for planning within a fairly tight time frame, without hindering on quality. I know the whole team worked hard to help bring our vision to life and it’s been brilliant working with them over the last 18 months. They have shown a great ability to solve any issues that arose quickly and are able to communicate effectively with different contractors at all levels. I have no doubt the next redevelopment project will go well.
We chose Alan and John for our extensive project and incredibly pleased with that choice and the result. We have a Victorian terraced house and wanted to do a classic loft conversion and ground floor extension. The Armstrong Simmonds team provided a vision which achieved our goals, but with a design we could have never have thought of ourselves which we love. We used them from start to finish and are incredibly glad we did. Alan supported us through the tender and renovation processes, and we are incredibly pleased with the end-product and the quality of work of builder Cezar of Vecchini. We would highly recommend Armstrong Simmonds for their vision, design thoughtfulness and exceptional assistance through the project. Thanks team!
We worked with Alan and the team from Armstrong Simmonds for 3 years from start to finish to achieve the full renovation of a London townhouse. It was a challenging brief given the nature of the property but collectively what has been achieved is an outstanding end result. Alan and John thoughtfully incorporated our vision with the realities of converting an old Victorian house and the scrupulous attention to detail, symmetry and balance achieved in the design were instrumental in us choosing Armstrong Simmonds in the first place.
In addition Alan supported us through the tender and during the renovation working with our excellent builder Cezar of Vecchini to deliver the brief. I would highly recommend if you are looking for a team to turning your vision to the end product with a very high attention to detail while still being good humoured and a generally great guy to work with. Thanks again team. Dom and Kamilla
John and his team have been brilliant to work with for our full house renovation and extension in SW London. Our house is quite unique and that combined with it being in a conservation area we knew it wouldn’t be a straight forward planning process – but Armstrong Simmonds did a fantastic job and helped us navigate us through every step. We couldn’t be happier with the detailed design and outcome.
If you’re considering a basement project in London, we’d love to hear from you. Whether you have a clear idea or are just exploring possibilities, our team will help you unlock the full potential beneath your home. We can advise on the cost of basement conversion London and support you from initial concept to completion.
Architect's studio/ Basement Conversion Architects
