Four waterproofing settings show blue wall protection, a charcoal-grey flat roof, blue basement tanking and blue waterproofing beneath shower tiles.

Which waterproofing product do you need? A UK guide to coatings, membranes and tanking

11 de noviembre de 2026

“Waterproofing” covers a lot of very different jobs — keeping rain out of a wall, stopping ground water in a basement, sealing a flat roof, protecting a wet room before tiling. No single product is right for all of them. This guide matches the job to the right product, so you order the correct thing first time.

Start with the question: is the water coming from rain (walls, roofs), from the ground (basements, floors, rising damp), or from inside (showers, wet rooms)? The source points you to the product.

Rain on walls and masonry → breathable membrane paint

For external walls, render and masonry that soak up driving rain, you want a coating that blocks liquid water but still lets the wall breathe outward. Poseidon Waterproof Membrane Paint is designed for exactly this — a flexible, breathable waterproof layer over masonry and render. It's the go-to for penetrating damp through an external wall.

Roofs, gutters and tough, flexible protection → high-build flexible coating

Flat roofs, box gutters, balconies and surfaces that move or take a beating need a thick, flexible, crack-bridging coating. The GOAT Flexible Waterproof Coating is a high-build, roller-applied liquid that forms a seamless, elastic waterproof skin — ideal where flexibility and durability matter most. See how to waterproof a flat roof.

Ground water, basements and floors → liquid damp-proof membrane / tanking

When water is coming from the ground — a basement, a cellar conversion, a floor slab, or a failed damp-proof course — you need a tanking-grade barrier. Waterproof Blue Liquid DPM brushes or rolls on to form a seamless, continuous damp-proof membrane across walls and floors, tying them together with no joints for water to find. It's the basis for tanking a basement from the inside and treating rising damp.

Showers and wet rooms → internal tanking before tiling

Behind the tiles of a wet room or shower, the waterproofing is what actually keeps water out of the structure — the tiles and grout are not watertight on their own. A liquid tanking layer applied before tiling seals the floor and walls. See how to waterproof a wet room before tiling.

Quick reference

External wall / render soaking through → Poseidon (breathable membrane paint)
Flat roof / gutter / balcony → The GOAT (flexible high-build coating)
Basement / cellar / floor / rising damp → Blue Liquid DPM (tanking membrane)
Wet room / shower before tiling → internal liquid tanking

The rule that applies to all of them: breathability and continuity

Two principles cut across every waterproofing job. First, on walls that need to dry out, choose a breathable system so you don't trap moisture behind the coating. Second, waterproofing only works if it's continuous — a liquid-applied, seamless layer that wraps corners and junctions beats anything with joints and overlaps, because water always finds the weak seam.

Frequently asked questions

Can I use one product for everything?

No — a breathable masonry paint, a flexible roof coating and a tanking membrane are formulated for different jobs. Using the wrong one (for example a non-breathable coating on a wall that needs to dry) causes new problems.

What does “breathable” actually mean here?

It means the coating stops liquid water getting in while still letting water vapour pass out, so the wall can dry. It matters most on walls; a flat roof is a different case.