Type A
Barrier protection
Cementitious slurries and spray applied membranes, forming a continuous barrier against the structure. Suitable where the structure is sound and the head of water is modest and well understood.
Hand & spray applied
Areas we cover · SW1, W1
Basement waterproofing in Westminster.
Westminster approved more basement schemes than almost any borough in London through the boom years, and it now applies one of the tightest policy regimes in the country. The ground itself is manageable — London Clay over much of the borough, gravels as you drop towards the river — but the constraints around it are not. Listed fabric, party walls on both sides and streets that cannot be closed shape the waterproofing design as much as the water does.
Ground conditions
What sits beneath Westminster.
| Postcodes | SW1, W1 |
|---|---|
| Geology | London Clay, with Thames river terrace gravels on the low ground towards the river |
| Groundwater | Tidal influence near the embankment; the culverted Tyburn crosses the area on its way to the Thames |
| Housing stock | Georgian and early Victorian townhouses, stucco terraces and mansion blocks, a very high proportion listed |
Westminster expects a structural methodology statement and a construction management plan with a basement application. The waterproofing strategy needs to exist at that point, not be resolved on site later, because it forms part of what is being assessed.
Westminster is one of the areas we cover across Central London.
Specification
Choosing the right system for Westminster.
BS 8102 sets out three forms of protection. Which one suits a property in Westminster depends on the water head, the condition of the structure and what you intend to use the space for.
Type B
Structurally integral
Water-resistant concrete construction, with joints and service penetrations designed as part of the structure. Usually the route for new basements and underpinned extensions.
New build & underpinned structures
Type C
Drained protection
Cavity drain membrane, perimeter channel and a pumped discharge. It manages water instead of resisting it, and it remains maintainable — which is why it suits most conversions of existing cellars.
Maintainable · Grade 3 habitable
Nearby
We also work in these areas.
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Tell us what you're seeing and we'll tell you honestly whether it needs a full waterproofing system or something much simpler.