What Is Rising Damp

Capillary Attraction

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

Capillaries in charcoal (1500x)

Capillaries in limestone

Rising damp is water’s natural tendency to rise in the brickwork. Because of certain physical laws, water will rise inside the capillaries. This is called capillary attraction or capillarity.

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.

Capillary attraction in glass tubes

Capillary attraction
in glass tubes

Capillary attraction in brickwork

Capillary attraction (rising damp) in brickwork

How Can You Recognize 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 (click to enlarge):

Tide mark

Tide mark on wall

Discoloration

Salt bands

Peeling paint

Damaged paint

Damaged paint and plaster

Plaster damage

Sandy plaster

Soft, sandy plaster

Building fabric damage

.

Watch the capillary attraction demonstrated on a short video. The thinner the gap between the glass panes the higher water will rise.