The GOAT liquid waterproof membrane applied to below-ground concrete foundation walls during construction

How to Waterproof Foundations with The GOAT Liquid Membrane

Foundations sit in the wettest, most punishing environment of any part of a building. Groundwater, rising damp and hydrostatic pressure work on them year-round, and once water finds a path through below-ground concrete or masonry, the damage travels up through the whole structure. Getting foundation waterproofing right at the build stage — or during remedial work — is far cheaper than dealing with water ingress later.

Why use a liquid-applied membrane on foundations?

Traditional sheet membranes rely on laps, welds and mechanical fixings — every one a potential failure point, and every complex junction a headache. A liquid-applied membrane like The GOAT flexible waterproof coating forms one seamless, fully-bonded layer over the entire foundation, moulding itself around penetrations, kicker joints and awkward details with no seams to fail.

Foundation wall coated with The GOAT black liquid waterproofing system to prevent water ingress below ground level

What makes The GOAT suited to foundation work?

The GOAT is a solvent-free reactive polymer engineered for exactly these conditions:

  • Applies to damp surfaces at 0°C — standard coatings need dry substrates and 5°C or above, which UK groundworks rarely offer. The GOAT goes on damp concrete in near-freezing conditions, so the programme keeps moving.
  • Handles positive and negative water pressure — essential below ground, where water pushes against the structure from the outside and moisture vapour drives through from within.
  • Fully bonded and flexible — it bridges shrinkage cracks and moves with the structure rather than debonding.
  • Independently certified — CE-marked and assessed by ETA-Danmark under ETA-25/0471, with a 25-year assessed working life.

Where to use it

Typical foundation applications include external faces of foundation walls before backfilling, kicker joints where the wall meets the slab, basement walls and basement roofs, pile caps and ground beams, and the junctions around service penetrations.

Internal damp proof membrane application compared with external below-ground foundation waterproofing on concrete walls

Which grade do I need?

For the large flat and gently sloping areas — foundation walls, slabs, basement roofs — use the 18kg roller grade, which is designed to cover big areas quickly by brush or roller. For kicker joints, upstands and vertical detail work, the 7.5kg thicker grade is mixed to a higher viscosity so it grips vertical surfaces without slumping. Both are available in black, grey and white.

Application in brief

Prepare the substrate by removing loose material and standing water — damp is fine. Apply the first coat by brush or roller, working the material into joints and details, and embed CORNER BAND or NW MESH T30 at junctions and crack-risk areas. Apply the second coat once the first has cured. The GOAT is quick-drying, so foundations can typically be backfilled or built on sooner than with traditional systems.

Questions about a specific foundation detail? Get in touch with our technical team — or head straight to The GOAT 18kg and The GOAT 7.5kg product pages.

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