Liquid Waterproof Membrane: The Complete Guide
What is a Liquid Waterproof Membrane?
A liquid waterproof membrane is a paint-on (or spray-on) coating that cures into a seamless, flexible, watertight layer. Unlike sheet membranes, there are no joints, overlaps or welds — the places traditional waterproofing fails. Because it's applied as a liquid, it follows every corner, upstand, pipe penetration and awkward detail perfectly.
Where Liquid Waterproof Membranes Are Used
- Bathrooms and wetrooms — tanking walls and floors before tiling. Our Poseidon Waterproofing Membrane Paint is NHBC-standards-ready and applied by roller or spray.
- Floors and foundations — as a liquid damp proof membrane (DPM). Waterproof Blue Liquid DPM protects against rising damp and ground moisture.
- Flat roofs, balconies and terraces — The GOAT flexible waterproof coating, available in black, grey and solar-reflective white.
- Façades and external walls — Passive Purple External, the fire-rated airtight façade membrane.
- Brickwork — Passivhaus Brickseal cream makes masonry water-repellent while staying breathable.
Liquid vs Sheet Membranes
| Liquid membrane | Sheet membrane | |
|---|---|---|
| Joints & seams | None — fully seamless | Every overlap is a risk point |
| Complex details | Coats them directly | Requires cutting & patching |
| Speed | Up to 300m²/day sprayed | Slower, labour-intensive |
| Movement | Flexible, crack-bridging | Can tear at fixings |
Choosing the Right Product
Bathroom or wetroom? Poseidon. Damp floor or foundation? Waterproof Blue. Roof or balcony? The GOAT. External wall or façade? Passive Purple External. Exposed brickwork? Brickseal. Not sure? Ask our technical team — a photo and a sentence is usually enough for us to point you at the right system.