Practically all buildings are surrounded by natural moisture which is trying to get into the dry structure of the building.
It is when building design precautions are inadequate or through lack of maintenance that dampness penetrates. Although any indication of dampness in the lower part of the wall is often diagnosed to be 'Rising Damp,' condensation or penetrating damp can create this condition making it essential for expert diagnosis to be made if unnecessary and costly procedures are to be avoided.
Below are some of the main causes of rising damp 

(DPC = damp-proof course)