Rates in this note are current at 26 July 2025. The live rate card is in the build cost calculator.
Basement contractors in London. We design, engineer and build basements under one contract. Basement cost in London, the 2026 figures.
In London’s prime postcodes, space is a luxury. Homeowners in Mayfair, Knightsbridge, Belgravia and Chelsea are looking for space without moving. Two routes do most of the work. One is digging a basement. The other is building out on the roof.
Basement Extensions: The Space Creator
In densely built areas, extending downwards offers significant advantages. Basements can be transformed into luxury amenities such as:
- Private cinemas with acoustic insulation and bespoke seating
- Wellness suites featuring pools, saunas and treatment rooms
- Wine cellars and tasting areas with climate control
- Secure underground parking for classic and supercars
Basement projects are complex and require experienced contractors. But the results can dramatically increase both usable space and property value.
Roof Terraces: Elevating Lifestyle and Views
Where basement extensions go below, roof terraces open up the skyline. A well-designed terrace offers:
- Outdoor kitchens and entertaining spaces
- Fire pits, ambient lighting and weather-proof furniture
- Landscaping that creates a private oasis above the city
- Panoramic views, adding a sense of luxury and exclusivity
For period properties, roof terraces require careful planning and expert handling. They must comply with building regulations and conservation requirements.
How NU Projects handles both
Both routes involve strict planning rules, structural work and a high level of finish. NU runs the design, the cost plan and the build under one contract. That means one team is answerable from planning consent through to the last detail.
Maximising Property Value
When done correctly, these renovations improve living experience. They also significantly enhance asset value. In prime areas, property prices are measured in thousands per square foot. Additional space translates directly to higher returns. That is true whether it is underground or on the roof.
You may be weighing up a basement or a roof terrace. We can walk you through what each one involves.
To talk to the team, send two lines through the contact form. You can also call 020 7731 6841. We usually reply within a few hours, weekends included.
This is the work we do. Basement contractors in London, or ask for a cost estimate.
Published 26 July 2025. Written by the NU Projects studio, edited since for house style and accuracy.
