The localised build-up of excess water or moisture that has no means of escape is called damp. If left untreated, dampness in buildings can lead to structural deterioration, corrosion of metallic fixtures, decay of timber, peeling of paint, mould growth and mites ultimately reducing the life of the structure.

Most building materials contain moisture to a certain degree. Materials like brick begin life dry and expand as water enters its pores over time thereby becoming a source of moisture. To prevent adverse damp effects, understanding damp and its causes is vital.