Basement Conversion

The opportunity to convert a basement in or around London is a unique prospect packed with potential. But it requires an architect who understands your vision, your lifestyle and the local protocol. Scenario Architecture has been designing high-end, hard-working contemporary homes across London for more than a decade. One of the top small architects in the city for house building, Scenario has featured in Elle Decoration, Dezeen and Houzz, and its modern design has been shortlisted for several prestigious architecture prizes – including the 2018 RIBA London Awards. When you convert a basement in London, Scenario is a skilled and proven partner.

We established our boutique firm in 2007 with a vision to develop a uniquely collaborative architecture, where clients who wish to convert a basement get a high-functioning first-class partner. Devising a liveable, modern design is the product of a deep understanding of each homeowner’s unique lifestyle. That shows in our design, and it’s made Scenario one of the best small architects in London for building a house.

Basement Conversion Your intention to convert a basement

Convert a basement in London

If you plan to convert a basement in or around London, Scenario is here to help.

Most architecture projects in London require planning permission from the local council. With our successful record securing planning permission for House Building projects on behalf of our clients, we can claim home advantage across the capital.

We’ve created a brief illustrated overview to help you understand each stage of the House Build process.


Discover if your chosen architect has had success steering planning applications through your local council. Visit the “planning applications” page of your council’s website and enter the architect’s name in the search criteria.

Basement Conversion


To help you understand what it takes to obtain planning permission to convert a basement in London, we’ve created this helpful guide. Download it below.
Planning guide

Basement Conversion Basement Conversion with Scenario Architecture

Working with Scenario Architecture to convert a basement

Scenario is a boutique architecture studio focused on high-end House Building projects in and around London. Through our bespoke modern design service, we tackle projects of every scale and complexity, from new-builds and full renovations down to interior alterations and refurbishments.

Our highly skilled team can walk you through the steps required to convert a basement. We collaborate closely with our clients from the initial drawings, detail design and planning through tender and construction to the project’s successful completion. On time and on budget.

We use innovative 3D design and visualisation tools as a standard for all projects. Our experience shows that real-time visualisations and virtual reality are efficient tools for choosing finishes, fixtures and fittings, and simulating natural light. And our expertise with 3D building information modelling (BIM) technology produces reliable construction information, so all our project data comes from an accurate, coordinated 3D model. Using this cutting-edge technology collaboratively with consultants and contractors saves our clients time and money.

A Chartered Institute of Building case study featuring a Scenario project demonstrates the great benefits of this advanced technology for domestic architecture.

Scenario Architecture is a RIBA Chartered Practice. We comply with the strict criteria of the Royal Institute of Chartered Architects, covering insurance, health and safety and quality-management systems.

Basement Conversion

Wrap-around extension and full renovation

Basement Conversion

Extensive renovation within a conservation area

Basement Conversion

Full refurbishment of a terraced house

Basement Conversion >> Your Basement Conversion Project Further Reading

Basement conversions have got a bad rap over the years, from households digging down multiple levels and edging dangerously close to their neighbours’ property lines. These “mega-basements”, or so-called iceberg houses, cause controversy for their deluxe features, like swimming pools, cinemas, wine cellars Turkish baths and car parks.

Building below street level can significantly increase the size of a home where conservation laws restrict expanding up and out. And new rooms below the main floor almost always make financial sense in high-value areas like London. But the more commonly sought and approved versions seek to enlarge an already existing coal hole or cellar. Even the most basic below-ground extensions will cost the same as a loft conversion, yet they’ll provide far more space for the outlay – most basement conversions in London start at about 40 square metres in size, growing to nearly 200 square metres.

Most basement conversions will require local Building Regulations approval, a sign-off from the neighbours and savvy planning. As most existing subterranean spaces lack any significant head height, most require excavation and underpinning. The height of the water table and location of sewer drains are an issue. And if the space lacks any access to light, a lightwell, an opening in the home’s entryway or glazing in the interior stairwell will need to be considered. If your basement conversion forms part of a larger all-over renovation, you can fold the assessment and application costs into your overall budget.

All that aside, converting a basement makes sense for families that intend to stay put and use it. Anyone looking for extra storage space, a separate playroom for growing children or a tucked-away space for utilities will find all these can be covered off in a single excavation. A well-planned basement can be the difference between staying in a beloved city home or leaving for the outskirts.

To make the most of your investment, you’ll want to consult an architect well versed in the local building codes and permissions protocol, and experienced in converting the vernacular architecture. If your home dates back more than a century, an architect that deals in period properties will be able to assess ballpark costs and potential risks with a single meeting. A good architect will be on hand throughout your project, overseeing quality control and serving as a liaison until the basement is properly executed.

Talk to us about your project

We would love to hear about your project and discuss how we can help

Please use the link below to schedule a call at a convenient time

Select a day


Select a time


Contact Information

Any information you provide us remains strictly confidential


Any information you provide us remains strictly confidential

Ownership status for the project

The property is

Any information you provide us remains strictly confidential

Property type

The project is

Any information you provide us remains strictly confidential

Aims of the project

Your budget

Any information you provide us remains strictly confidential

Please indicate an estimate of your target budget (excluding VAT and professional fees) so we can advise on the viability of your requirements

Budget range

Additional information

Any information you provide us remains strictly confidential

Please attach files such as plans, estate agent brochures, image and surveys

Basement Conversion In our clients words


We wanted to renovate our house in a conservation area in central London. Given this involved a complete demolition and new build with an extra floor on top, getting planning approval was always going to be tricky. Scenario did an amazing job on the new house ‘envelope’ and throughout the planning phase. We couldn’t have wished for better from them and having succeeded in gaining planning approval owe them a very big ‘thank you’.


Scenario designed a kitchen extension for us, and we are delighted with the results. The process was well organised, planned and delivered, and the whole team were a pleasure to work with. I would highly recommend them for their design, planning and project management skills.


Worked with these guys on the internal development of our office. From start to finish they were great. They got what we wanted first time and really made working with them very easy. Their aftercare has been great too helping us deal with something that they were not involved with in the first place. Will highly recommend them to anyone.

See all Google reviews