Basement Construction London | Design & Build Specialists

Before starting a basement construction in London, it’s essential to assess ground conditions, neighbouring structures, and any potential impact on drainage and waterproofing. Local planning permission and structural surveys should be secured early to avoid delays. Working with experienced basement contractors in London ensures your project complies with all safety and building regulations from day one.

The timescale depends on the scope and complexity of your project. A straightforward basement conversion can take around 16–24 weeks, while a full new-build basement or multi-level extension can take 6–12 months. Factors such as design detail, site access, weather, and council approvals all influence the duration.

In most London boroughs, planning permission is required for basement construction, especially if excavation extends beyond the footprint of your home or adds light wells or external access. For smaller internal conversions, you may only need a Certificate of Lawfulness. Our design and planning team can handle all planning applications and basement impact assessments on your behalf.

The cost of a London basement conversion typically starts from £3,000–£4,000 per square metre for a retrofit and £4,500+ for new-build basements, depending on design complexity and finishes. Factors such as access, waterproofing systems, and structural design influence the total cost. We provide transparent, detailed quotations after a full feasibility study.

At Basement Structures, we use advanced basement waterproofing systems approved to BS8102 standards. These include cavity drain membranes, sump pumps, and fully integrated drainage systems. Our waterproofing is designed and installed by certified technicians to ensure your space remains permanently dry and structurally sound.

We specialise in all types of luxury basement construction including home cinemas, gyms, swimming pools, wine cellars, and additional living spaces. Each project is bespoke, designed to complement your home’s architecture and maximise usable space while increasing property value.

With over 30 years’ experience in basement construction across London and the South East, our team delivers complete design-and-build solutions from excavation to finishing. We combine engineering precision, transparent communication, and attention to detail to create safe, high-quality underground spaces that stand the test of time.