Penetrating damp can arise as a result of a wide variety of causes e.g. building defects, such as cracked and defective external rendering, damaged and detective rainwater goods, i.e. downpipes and gutterings, leaking roofs, high external ground levels or poorly fitted or rotten joinery.
The penetration of moisture through external walls at low level can often be confused with rising damp, and care must be taken during an inspection to accurately identify all building defects that may be contributing to dampness within the property. Again wet and dry rot attacks are often instigated by external defects, allowing water to penetrate the fabric of the building.
Rising damp is caused as a result of water migrating through the capillaries of the materials with which most buildings in the UK are constructed. This primarily will be either stone or brick or other regional methods of construction. As well as these, there are the materials which are used to bond these substrates together, for example, mortar (which can be in varying types of mix including sand and cement),ash and various other materials which have been used throughout the centuries. Water can travel through these capillaries to a height determined by the narrowness of the capillary tube. The narrower the capillary tube, the greater the height reached.