Trusted Basement Specialists Locals Rely On
Finding basement specialists in London who actually understand the city’s ground conditions is harder than it sounds. Dig in Kensington, and you’ll hit London Clay. Move three streets over near an old river course, and the water table climbs fast. That inconsistency is exactly why generic contractors get basement projects wrong.
WJB Ground Works is the trusted local basement specialists London that has built and converted basements across Greater London since 2014. We run the whole job ourselves, from geotechnical survey through excavation, waterproofing and Building Control sign-off. No handoff to a third party halfway through, which is usually where accountability disappears on a basement conversion.
Trusted basement specialists in London. Book a survey today.
Get a Free QuoteWhy Our Basement Specialists Get the Structural Phase Right First
Basements don’t fail loudly. A basement conversion fails quietly, months or years after handover, when a Type A membrane was specified where a Type C drained system was actually needed. By then, you’re excavating a finished room to fix a decision made before the slab went in.
Good basement specialists answer the hard questions early. What’s the groundwater level doing across seasons? Is the site Grade 3 or Grade 4 for its intended use? Does the retaining wall design allow for surcharge from next door’s foundation? BS 8102:2022 recommends combining two waterproofing types for most habitable basement conversions, not choosing one and hoping. As London basement specialists, we design to that standard as a baseline.
Our Basement Services Across Greater London
We handle the full below-ground scope. Homeowners, developers and architects across Chelsea, Kensington, Fulham, Wimbledon and wider Greater London use our basement specialists for:
- New-build basement construction under single dwellings and larger residential schemes.
- Basement conversions that extend an existing cellar into liveable, warrantable space.
- Retaining walls in contiguous, secant, or reinforced concrete form, sized to the ground data.
- BS 8102 Type A, B and C basement waterproofing, specified individually or combined by risk grade.
- Underpinning to create headroom or strengthen a foundation before excavation.
- Dewatering and groundwater control on high water table sites across the London Basin.
- Party Wall etc. Act 1996 notices, schedules of condition, and award liaison are handled in-house.
- Basement excavation logistics for sites with narrow access, listed neighbours, or restricted hours.
- Structural slabs, walls and roof construction to your engineer’s design.
Every basement is built to Building Regulations Part A and Part H. Our CHAS-accredited safety lead is on every site, not on a rota.
How Our Specialists Deliver a Basement Project, Start to Finish
Our basement delivery follows a strict sequence to prevent problems later on:
Survey and Design
Borehole investigation and groundwater monitoring over time; party wall review with neighbours identified early by specialists.
Temporary Works and Excavation
Propping installed first; staged excavation checked against design at each level with engineer sign-off required.
Structure and Waterproofing
Retaining walls, base slab, and waterproofing system installed sequentially; every stage inspected before being covered up.
Sign-Off and Handover
Building Control completion. Party wall finalisation with the adjoining owner. Snagging cleared before keys are handed back.
Why London Homeowners Choose These Basement Specialists
There’s no shortage of basement contractors in London. Most clients choose our basement specialists because of what happens after the first project, not during it.
Broken-down quote provided before any commitment is made.
Clay, made ground, and high water tables near old rivers.
Excavation, structure, waterproofing, drainage; one payroll, one standard.
Single point of contact across every basement conversion stage.
Notices served correctly, disputes avoided before they ever started.
Building Control and NHBC requirements are met as standard practice.
Verified safety management, externally checked, not self-certified internally.
Surveyors and architects refer projects after working with our specialists before.
One team carries risk, responsibility never lost between trades.
Greater London, Surrey, Essex, Luton, operating since 2014.
FAQs About Basement Projects Specialists in London
Ground investigation, temporary works design, excavation, retaining wall and slab construction, waterproofing, drainage, and Building Control sign-off. Our basement specialists manage each stage in-house.
A conversion beneath an existing house typically runs 16 to 28 weeks. A new-build basement folded into a larger project usually adds 12 to 20 weeks to that programme. Groundwater and access are what move the timeline most.
It depends on the risk grade for how you’ll use the space. A low-use storeroom might get away with a single system. A habitable room below ground almost always needs two types combined, usually Type B integral protection with a Type C drained cavity behind it.
Sometimes, sometimes not. A conversion under an existing footprint may fall under Permitted Development. A new excavation, a listed building, or anything touching a party wall usually needs consent and a Party Wall Act process alongside it.
Yes. We prepare and serve notices, arrange “schedules of condition” with neighbouring properties, and coordinate with surveyors where an award is required. This sits inside our service, not something you chase separately.
Yes. Survey, temporary works, excavation, basement structure, waterproofing and drainage all sit with our own team. You get one point of contact for the whole basement build, not a chain of subcontractors.
After the site survey and design stage, we send an itemised breakdown by phase. Ground conditions, waterproofing type, access restrictions, and any party wall costs identified early all feed into the final number.
Depending on the site conditions, drainage can include land drains, a sump and pump system with battery backup, and foul or surface water connections installed according to Part H standards. Sites with a high water table typically require redundant pumping systems equipped with alarms as a standard feature.