The 5 best basement renovations in London that make going underground worth it
Tucked beneath the streets of London lies a world of untapped possibility. For many homeowners, the basement is a blank canvas waiting to become something extraordinary.
A well-designed conversion can turn that overlooked lower level into a cosy hideaway, a sleek workspace, or even a light-filled lounge that feels nothing like a cellar. And in a city where space is at a premium, making the most of every square foot is not just smart, it’s essential.
We’ve rounded up some of the best basement designers and conversion specialists across London known for blending style with structural savvy. If you’re ready to reimagine your downstairs space, these experts know exactly how to bring it to life.
What is the average cost of basement renovations in London?
The average cost of a basement renovation in London ranges from £1,500 to £2,500 per square meter. For a full conversion—including excavation, underpinning, and fit-out—expect costs between £200,000 to £500,000, depending on complexity and size. High-end finishes or listed buildings can push costs to £3,000 per square meter.
1. Advantage Basements
Address: 95 East Hill
Contact: +44 20 7760 1617
Mail: [email protected]
Business hours: Monday to Friday, 9AM – 5PM
Advantage Basements has been a steady presence in London’s basement scene since 2000, with both directors bringing over 30 years of hands-on experience. They’ve carved out a solid reputation, especially among homeowners who value transparency and clear communication.
One recurring theme in client feedback is how closely the team works with clients—not just during planning, but throughout the build. Their attention to detail often translates into fewer surprises and smoother timelines.
While they may not push the envelope on ultra-contemporary design, they excel at delivering clean, well-executed builds that stay on brief and on budget.
Some reviews mention that the company prefers to stick to projects that fit their established process, which might not appeal to those chasing something highly bespoke.
Still, for anyone looking for a dependable team with a practical, straight-talking approach, Advantage Basements earns its place on this list.
Skilled team
“We recently had Advantage Basements complete a full creation of a new habitable basement under our existing property—and the results are absolutely outstanding. From start to finish, the team was professional, reliable, and incredibly skilled. The quality of their workmanship is truly top-tier. Every detail was handled with care and precision. The crew was civil, tidy, and respectful of our home, keeping us informed every step of the way. Transforming what was once unused space into a beautiful, fully livable area has added tremendous value and enjoyment to our home. We highly recommend Advantage Basements to anyone considering any type of residential work done. Truly a 5-star experience!”
- NF, Google Review
Professional approach
“We are very happy with Advantage Basements. Their quote was competitive, but importantly they were professional – advising clearly on the processes, time lines and costs. They offered valuable guidance during the design stage. Despite living in the house while the work was being done beneath us, the courteous and professional approach of their teams made the entire experience as smooth and stress-free as possible. Once the project was completed, they ensured everything was perfect and they addressed any follow-up questions or concerns. It’s clear they take pride in their work and are committed to customer satisfaction. We have no hesitation in recommending Advantage Basements.”
- Steve Ford, Google Review
2. OBS Basements Ltd (EC2A)
Address: 3rd Floor, 86 – 90 Paul St
Contact: +44 7594 954319
Mail: [email protected]
Business hours:
- Monday to Friday, 6:30AM – 6PM
- Saturday, 7AM – 6PM
OBS Basements has been quietly building a reputation over the last decade for solid, technically sound conversions that don’t cut corners.
They’re not flashy, and that seems to be the point—clients tend to highlight how grounded and methodical the team is, especially when it comes to structural integrity and waterproofing.
There’s a reassuring consistency in their projects, and while they’re not the go-to for highly stylised or design-heavy finishes, their work holds up well over time. That said, those after bold aesthetics or architectural flourishes might find their style a bit reserved.
OBS seems more focused on function than flair, and they’re selective with the jobs they take on. But for anyone prioritizing durability, clean execution, and a builder who doesn’t overpromise, they’ve proven themselves reliable.
Their near-flawless review record isn’t a fluke—it reflects a team that takes its time to get things right.
Fantastic job
“OBS were fantastic from start to finish. They were able to begin work within a couple of weeks from our first meeting. They quoted an overall fee which covered everything, so no hidden extras! It was also clearly itemised, so the billing was just very transparent and stress-free. They organised every aspect of the project, including getting the steel frame fabricated, the skip, the electrician, deliveries, and various other moving parts. The workers were professional, skilled, on time, friendly, and flexible. The overall quality of work and customer service was fantastic. We also felt like we got good value for money. We would highly recommend OBS to anyone renovating their basement.”
- James Smith, Google Review
Good communication
“When Kendall and David first met me on site their positivity, confidence and enthusiasm shone through. After visiting their other ongoing projects I was sure they would be able to handle mine. There was good communication throughout the job. They dealt with the complexities of the project in their stride and kept to their costing. They were diligent and proud of their work and a friendly company to deal with. A good result on completion. I would be happy to use them again on a basement project.”
- Arnold Vanslembrouck, Google Review
3. Micheal Brady Ltd
Address: Monument House, 215 Marsh Rd, Pinner
Contact: +44 20 8900 2345
Mail: [email protected]
Business hours: Monday to Friday, 9AM – 5PM
Micheal Brady Ltd stands out for its sharp project coordination and ability to handle complex basement builds without letting things spiral out of control.
This isn’t a team that improvises—they’re known for keeping a tight grip on schedules and paperwork, which clients seem to genuinely appreciate.
They cover the full scope, from structural calculations to final fit-out and bring in specialists where needed rather than trying to do everything in-house. It’s a model that works well for larger or more technical conversions.
That said, the company leans toward high-precision builds, so you might find less flexibility if your vision veers into the unconventional or design-led. Their projects tend to favor solid execution over bold experimentation.
But if you’re planning a major excavation or want someone who can calmly navigate planning challenges, they’re worth a look. Their approach may not be flashy, but it’s highly dependable—something many London homeowners find invaluable.
Very professional
“We have worked with MBL on a number of projects and have found them to be professional, collaborative, efficient and their work is of the highest quality. I highly recommend it.”
- Tom Davies, Google Review
Helpful team
“Fantastic family construction company.high end new build and refurbishment work.friendly, helpful team.”
- Gilly Bennett, Google Review
4. London Basement
Address: Suite 6, 2 Shad Thames
Contact: +44 20 8847 9449
Mail: [email protected]
Business hours: Monday to Friday, 6AM – 10:30PM
London Basement has carved out a niche as a one-stop shop for basement conversions, handling everything from structural engineering and planning permission to finishes and lighting. What seems to set them apart isn’t just the range of services, but how smoothly everything runs.
Reviews often highlight how the team keeps projects on track without leaving clients buried in admin or chasing answers. Their site teams are tidy, too—a detail small on paper, but big in day-to-day experience, especially if you’re living onsite during the build.
That said, their all-inclusive model may not appeal to homeowners who want more creative control or plan to bring in their own designers.
Their process leans toward efficiency and polish rather than custom experimentation. But for those looking for a firm that takes care of the legwork and delivers a clean, well-managed result, London Basement has earned a reputation for making it look easy.
High quality project management
“London Basement provides a high quality turnkey service (Constructions, Project Management, Planning, Engineering, Building Control Regulations), cutting off all the stress for the clients.
I met the London Basement team during a site inspection in Chelsea, and I was really impressed. High professional service.”
- Giacomo Mascia, Google Review
Perfect job
“I chose the London Basement service for the full refurbishment of my property and the new basement. The team did a perfect professional job and they have dealt with all the aspects of the project and construction.”
- Dominique Charleux, Google Review
5. More Space Building Solutions Ltd
Address: Office No. 127A, 268 Bath Rd, Slough
Contact: +44 7404 961606
Mail: [email protected]
Business hours: Monday to Friday, 9AM – 5PM
More Space Building Solutions tends to attract homeowners with big plans—those looking to push the limits of what their property can offer. Their portfolio leans heavily on large-scale conversions and extensions, often combining multiple upgrades into a single build.
It’s clear they’re comfortable operating at scale, and that shows in their planning, coordination, and ability to deliver polished results across the board.
Clients often mention the firm’s attention to finishing details, particularly in how well new spaces blend with the existing property.
That said, this kind of work doesn’t come cheap, and More Space seems better suited to homeowners who are ready to invest in getting everything just right.
They may not be the best fit for very tight budgets or projects that call for more experimental design thinking, but when it comes to smart use of space and crisp execution, they know their way around a complex brief.
Done well
“The expansion work has been completed, all projects were finished on schedule, and the workmanship is excellent. The outdoor work, such as decking and the gardening, was done very well. Compared to quotes from other construction companies, they are very competitive. All in all, if we need to do other projects, we will definitely seek their help.”
- Arnold Lee, Google Review
Good craftsmanship
“I recently had the pleasure of working with More Space Building Solutions for the refurbishment of my house, and I couldn’t be more delighted with the results. From start to finish, their professionalism, attention to detail, and commitment to quality were evident. First and foremost, their team displayed excellent communication throughout the entire process. They took the time to understand my vision for the refurbishment and offered valuable insights and suggestions to enhance the outcome.”
- Rana Hassam, Google Review