Service
Structural waterproofing design is the work of deciding, for every below-ground space, what performance it needs, which combination of BS 8102:2022 protection types will reliably deliver it in the ground conditions, and how the critical junctions are resolved - then writing that down as a specification a contractor can be held to. CLW does that work from RIBA Stage 2 through construction, independent of any product or installer.
What clients say
What the design consists of
This is what you receive when CLW is appointed to design the waterproofing. Each document answers a question the design team would otherwise leave to the contractor.
RIBA Stage 2
A site-specific BS 8102:2022 risk assessment: the ground and groundwater regime, the consequence of failure for each space, and the strategy that follows from it. The grade of protection is agreed with the client here, space by space, and recorded. This is the document that stops waterproofing being an assumption inherited from the structural scheme.
RIBA Stage 3
Drawings that show which BS 8102 grade applies where, the Type A / B / C combination selected for each zone and why, typical details, and the critical junctions - capping beams, podium interfaces, piles, penetrations, movement joints - resolved in principle. Reviewed against the structural and architectural drawings for compatibility, and coordinated in the design team meetings.
RIBA Stage 4
A contractual document that states what the waterproofing must achieve rather than naming products: the grade per space, the hydrostatic case, joint and movement requirements, protection, penetration and interface rules, testing and design life. Competent specialist contractors tender against it with their own systems, which opens the competition and keeps installation liability with the installer.
RIBA Stage 4b
Review of contractor proposals and product selections against the specification, attendance at technical interviews, responses to BS 8102 queries, and a plain recommendation. Bids are normalised so the client compares like with like.
RIBA Stages 5 to 6
Inspections at the critical stages of installation, review of the contractor’s QA submissions, written challenge of any departure from design intent, and a review of as-built and maintenance information at handover. It carries weight because CLW wrote the specification the work is being checked against.
The grades the design works in are set out in our BS 8102:2022 performance grades reference; how a grade is chosen for a given room is in what grade of waterproofing do I need. For a live London scheme, start with basement waterproofing consultants in London.
What you get
Robust enough to perform for the lifetime of the building. Efficient enough to avoid the cost of over-specification. Multi-disciplinary coordination with the rest of the design team.
RIBA 2–4 · BS 8102:2022 · CSSW + WDS registered designers
Specifications that open competitive tender among competent specialist contractors against their preferred products. Best-value procurement, not lowest-price race.
Performance spec · Open tender · Independence preserved
CLW remains appointed as client-side advisor through construction. Inspections at critical stages. Authority to challenge contractors when work departs from design intent.
Construction monitoring · CMT input · BS 8102 Clause 8
When to appoint
The earlier CLW is appointed, the more options remain on the table. By RIBA Stage 4, key Type A/B/C decisions and structural interfaces are often locked in. Sometimes against waterproofing best practice.
A CLW appointment at Stage 2 lets the design team shape the brief in ways that prevent risk rather than mitigate it. By Stage 3 we're producing the performance specification, and by Stage 4 we're in tender support and contractor selection.
Where the appointment comes later, Stage 4 or beyond. We do still help. The framing shifts from prevention to triage.
Send a project brief or put our AI agent to work first. Both routes get you a useful first answer in the right register.
