Applying Waterproof Blue liquid damp proof membrane to a basement wall to stop rising damp

Rising Damp: How to Spot It and Stop It for Good

Rising damp is one of the most misdiagnosed problems in UK housing — and one of the most damaging when it's real. This guide shows you how to tell rising damp apart from condensation and penetrating damp, and what actually fixes it.

Applying Waterproof Blue liquid damp proof membrane to a basement wall to prevent rising damp

What is Rising Damp?

Rising damp happens when groundwater travels up through brickwork and masonry by capillary action — the wall literally sucks moisture up from the ground. It occurs when a property has no damp proof course (DPC), or the original one has failed or been bridged.

The Tell-Tale Signs

  • Tide marks — a horizontal stain line, typically up to a metre above floor level
  • Peeling wallpaper and blown plaster along the base of walls
  • Rotting or decaying skirting boards and floor timbers
  • White salty deposits (efflorescence) left behind as the water evaporates
  • A persistent musty smell at low level

If your damp is higher up the wall, in patches, or worse after rain, you're more likely looking at penetrating damp or condensation — see our full guide to what causes damp walls.

What Doesn't Work

Painting over rising damp with standard paint, or dry-lining straight over it, just hides the problem while the moisture keeps climbing and the structure keeps deteriorating. Any real fix has to either restore the damp proof barrier or control where the moisture can go.

How to Stop Rising Damp

1. Apply a liquid damp proof membrane

Waterproof Blue Liquid DPM is a roller-applied, polymer-modified membrane that creates a continuous waterproof barrier on floors and the base of walls — the modern alternative to hacking off plaster and injecting chemical DPCs. It's seamless, flexible and crack-bridging, so it stays watertight as the building moves.

Waterproof Blue liquid DPM tin – roller-applied damp proof membrane for floors and the base of walls

2. Protect the external face

Where bricks are saturating from outside, Passivhaus Brickseal cream soaks into the masonry and makes it water-repellent while staying breathable — rain stays out, trapped moisture can still escape.

Roller-applying Passivhaus Brickseal breathable masonry sealer to exterior brickwork to keep rain out while letting the wall breathe

3. Let the wall breathe

Sealing a damp wall with non-breathable materials traps moisture. Our membranes are engineered to control liquid water while managing vapour correctly, so the structure can dry out rather than rot behind a coating.

Worried About a Damp Wall?

Send our technical team a photo and a description — we'll tell you honestly whether it's rising damp, penetrating damp or condensation, and which product (if any) you actually need. Contact us here.

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