Basement Conversions in London
Basement conversions in London demand more than standard building work. They call for a specialist team with the technical knowledge and design understanding to work within the city's diverse architecture and planning permission constraints.
Proficiency Design & Build has delivered bespoke basement conversions across Central London and the surrounding areas for over 14 years. From heritage homes in Kensington to modern residences in Clapham, our exceptional craftsmen create functional spaces that stand the test of time.
Down is the new up. In a city where space is a scarce resource, one solution is to dig deep.
Featured Building Project
Hampstead, NW3
This North London project demonstrates how we transform existing properties with a refined basement conversion and modern kitchen extension. The expanded lower level and open-plan layout create bright, connected spaces that blend functionality with contemporary design.
Get a Quote View ProjectWhy Choose Proficiency
Federation
of Master Builders
Our craftsmanship, track record, and financial stability have all been independently verified, providing clients with complete assurance of our professionalism.
Fully Insured
Extensive public and employers’ liability insurance, giving you peace of mind from concept to completion.
Considerate Constructors Scheme
Demonstrates our commitment to reducing environmental impact and minimising disruption to neighbours on every project.
Basement Design & Build Specialists
Basement conversions can be complex. When extending outward isn't possible and an upward expansion faces restrictions, our experienced building contractors offers tailored basement cellar conversions, from North London to South West London and everywhere in between.
Our basement conversion specialists combine structural expertise and advanced damp proofing solutions with bespoke interior design that transforms existing basements into the space of your dreams.
Whether it's a small, bespoke wine cellar, a relaxing home cinema room, a modern games room, or a full lower-level extension, our basement conversion company ensures your new space is finished to the highest standards.
Basement Conversion Process
Free On-Site Consultation
We begin with an on-site visit to assess feasibility, understand your basement space requirements, and identify any planning or structural considerations, such as soil conditions or water table levels. Transparent communication is at the heart of our service from day one.
Planning & Design
Our in-house team creates bespoke designs that bring your vision to life. We manage all planning permission applications, liaise with local authorities, and guide you through party wall agreements and building control requirements for a seamless approval process.
Excavation & Structural Works
Our extension specialists ensure all structural and basement excavation work complies with local regulations. Each stage is overseen by a dedicated project manager and structural engineer to ensure precise and safe builds.
Waterproofing & Drainage Installation
We install Delta Membrane Systems for proven, long-term damp protection, along with advanced drainage and ventilation systems to maintain a dry, comfortable living environment.
Fit-Out & Interior Completion
Finally, our interior design and finishing team tailors every detail of your basement project to your style preferences, from flooring and lightwells to bespoke joinery and décor, resulting in a refined space built to the highest standards.
Our Construction Company
Since 2011, Proficiency Design & Build has designed and converted countless basements across Greater London. Our 4.9/5 Google rating speaks volumes about our exceptional work ethic and customer service.
LATEST PROJECTS
Our Luxe Basement Conversion Services
REFURB
Basement refurbishment transforms existing basement spaces from dark and damp to stunning, functional rooms filled with natural light. Think high-quality home offices, spare bedrooms, cinema rooms, wine cellars, and more.
CONVERSION
Our London architects, interior designers, and basement contractors bring your ideas to life, managing all planning applications and construction to deliver exceptional results.
CELLAR
Whether you're upgrading an existing cellar or creating a new one, our team designs and builds bespoke temperature-controlled wine cellars or private areas for entertaining, tailored to your home and lifestyle.
What Does a Basement Extension Cost?
Every London basement conversion is unique, with basement conversion costs varying based on design scope, space, and finishes. Average costs for these basement space ideas are as follows:
- Swimming pool: Starting from £2,000 to £3,800 per square metre
- Home gym: Ranging from £1,800 to £2,500 per square metre (excl. equipment)
- Sauna: Roughly £3,000 to £15,000, depending on size and specs
- Living space: Averaging around £1,800 to £3,100 per square metre
- Utility room: About £7,000 to £15,000+ in total
Work With Local Basement Specialists
Contact Proficiency Design & Build for all your basement conversion in London needs.
