What is capillarity rising damp?

Capillary rising damp, frequently called “rising damp”, is a natural physical phenomenon that can often be found in old buildings. It is characterised by fracture lines present below the building (see diagram above).

The water running down these fracture lines creates friction and thus produces an electric charge varying between 50 and 500 millivolts.


This capillary tension causes soil water to rise from the soil (+) towards the walls (-) (see diagram above).

It has been proven that water molecules constitute dipoles (like magnets) that orient themselves so as to ascend through the pores of the walls thanks to a physical phenomenon called capillarity.



Rising damp is characterised by the presence of mineral salts in the walls, such as nitrates (coming from animal excrements) and sulphates (from rock).