What Rising Damp Actually Is

Rising dampRising dampMoisture from the ground that climbs up inside walls through the pores of the materials. It shows as stains, blown render and salts at the foot of walls. isn't just "a bit of moldMouldFungi that grow on damp surfaces, leaving black or greenish spots and a musty smell. It is a symptom of damp, not a problem with the paint." — it's a physical phenomenon that follows specific rules, and precisely because it follows rules, it can be fixed for good once you understand how it actually works.

Every masonry wall — brick, stone or concrete — is riddled with microscopic pores. When a building's foundation sits in contact with damp ground, water is drawn into those pores and travels upward through the wall by the same mechanism that pulls oil up a lamp wick. Scientists call this capillary action: the narrower a material's pores, the higher moisture can climb, typically up to about a metre above ground level.

Buildings constructed in Greece before the 1980s rarely included a horizontal damp-proof membrane in their foundations — something considered standard in every new build today. That makes them especially vulnerable, particularly when combined with a high water table, poor rainwater drainage around the building, or low-permeability rendersRender (plaster)A layer of mortar (sand, cement or lime, and water) spread over brick or concrete to give a wall a straight, sound surface ready for paint or tiles. that trap moisture instead of letting it breathe.

It's important not to confuse rising damp with simpler problems: a leaking pipe, a crackedCrackA split or gap in render, concrete, a wall, a coating or wood. Fine cracks are usually only on the surface; ones that grow, keep reopening or run diagonally need attention. roof, or plain condensationCondensationMoisture in the air turning to water on cold surfaces such as windows, outside corners and ceilings. It is the most common cause of mould indoors. from poor ventilation each have a completely different cause and a completely different fix. Getting the diagnosis right is the first and most critical step — treating the wrong problem just hides the symptom temporarily instead of solving it.