WHAT IS RISING DAMP?
Rising damp is water’s natural tendency to rise in brickwork. Because of certain physical laws, water will rise inside the capillaries. This is called capillary attraction or capillarity.
Paper, sponge and brickwork have all something in common: they are porous, their structure consists of millions of thin, microscopic channels called capillaries.
Capillaries in charcoal (1500x)
Capillaries in limestone
The height of the rising damp in the walls depends on several factors, such as the amount of water present in the soil, the porosity of the building materials, the weather etc. Rising damp is usually higher during the rainy season, or if the evaporation of the moisture is impeded in any way (e.g. using tiles, non-breathing cement plaster etc.
The narrower the capillaries the higher water will rise.
Watch capillary attraction demonstrated on this video. The thinner the gap between the glass panes the higher water will rise.
Capillary attraction in glass tubes
Capillary attraction (rising damp) in brickwork
HOW CAN YOU RECOGNISE RISING DAMP?
Rising damp can be recognized by a series of symptoms, which highlights the gradual destruction of the building.
The destruction process can take several years or decades, and it typically starts with the paint (stains, flaking, peeling), then if left untreated will starts destroying the plaster (initially sandy on the surface, then totally soft sand like), and in the final stage will damage the brick- or stonework (resulting in broken or cracked bricks, soft bricks, missing stones etc).
Here are some of the most typical signs of rising damp:
Tide mark on wall
Damaged paint and plaster
Soft, sandy plaster
Building fabric damage