From Structural Excavation to a Complete Waterproof Shell

Delta Force Group Ltd are trusted expert in basement construction throughout London. Whether you're building under an existing property, garden, or new development, we deliver complete basement structures from excavation to a waterproofed shell, ready for your fit-out team to finish.

What We Do

We provide end-to-end structural basement construction services, including:

  • Excavation & Soil Removal
    Safe, controlled excavation using diggers or hand-digging methods where access is tight.

  • Underpinning & Structural Support
    Installation of reinforced concrete underpinning or piles to support existing structures during the dig.

  • Formwork & Concrete Slabs
    We form and pour reinforced concrete slabs and walls to structural engineer specifications.

  • Waterproofing Installation
    We install Type A (tanking), Type B (integrated), and Type C (membrane & sump) waterproofing systems.

  • Sump Pumps & Drainage
    Full drainage systems and sump pump installations to manage groundwater and prevent flooding.

  • Backfill & Handover
    Once complete, we backfill and hand over a clean, dry waterproof shell — ready for follow-on works.

Basement Types We Build

  • ✅ Basements under existing houses

  • ✅ Garden basements

  • ✅ Side and rear basement extensions

  • ✅ New build basements

  • ✅ Full footprint basements

Under-Garden Basements

Transform the space beneath your garden into a functional living area with our under-garden basement construction services. We specialise in maximising space and natural light, creating a seamless extension of your home that blends beautifully with your outdoor surroundings.

Typical Timeline

  • Week 1–2: Setup, site prep, and initial dig

  • Weeks 3–6: Underpinning and deep excavation

  • Weeks 7–9: Concrete works and waterproofing

  • Week 10–12: Drainage, sump pumps, backfill, and shell handover

Timelines depend on project size and access conditions.

Underpinning Services

Our underpinning services are designed to strengthen and stabilise existing structures, including basement foundations. Whether you need to reinforce your basement walls or increase the depth of your basement, our team has the expertise to handle the job efficiently and effectively.

Why Choose Delta Force?

  • Over 15 years of basement construction experience

  • Fully insured and qualified groundworks specialists

  • Fixed-price contracts with staged payments

  • Health & Safety compliant with structural warranties

  • All work is over seen by structural engineers and waterproofing specialists

  • Trusted by homeowners, developers, and architects across London

Contact Us Today for Your Basement Construction Needs

Get in touch with Delta Force Basements for all your new build and under garden basement construction requirements. Our experienced team is ready to assist you with your project.