What Is Rising Damp?

Rising damp is moisture that travels upward through brickwork and plaster from the ground. It occurs when groundwater is drawn up through porous building materials like bricks and mortar.

Modern homes are built with a damp proof course (DPC) to prevent this. However, older properties may not have one — or the DPC may be damaged or bridged.

Signs of Rising Damp

Common indicators include:

• Damp patches starting at skirting level
• Tide marks on internal walls
• Peeling paint or wallpaper at the bottom of walls
• Crumbling plaster
• White powder (salts) on wall surfaces
• Rotten skirting boards

The key characteristic is that it starts low and rises upward.

How Is Rising Damp Different From Other Damp?

Rising damp is often confused with condensation or penetrating damp.

• Condensation usually forms on cold surfaces and in corners.
• Penetrating damp often worsens after rainfall.
• Rising damp begins at ground level and forms horizontal tide marks.

(Internally link to your condensation, penetrating damp and DPC posts here.)

What Causes Rising Damp?

Rising damp typically occurs when:

• The damp proof course has failed
• External ground levels are too high
• Debris or render is bridging the DPC
• The property has no DPC (common in pre-1900 homes)

True DPC failure is less common than often claimed.

How to Fix Rising Damp

The correct solution depends on the cause:

• Lower external ground levels
• Remove bridging materials
• Improve drainage
• Install a new DPC (if genuinely required)

Diagnosis is critical before expensive chemical injections are carried out.

Final Thoughts

Rising damp does exist — but it is frequently misdiagnosed. Proper inspection of external ground levels and wall construction should always come before invasive treatments.