Rising damp is the upward movement of moisture through walls and sometimes floors by capillary action from below the ground. It generally occurs up to 1.2 metres in the walls, depending on the masonry type and the outside ground levels. Salt deposits generally form a horizontal tide mark, below which there will be discolouration, peeling wallpaper and possibly white efflorescent salts which have been drawn out of the brickwork by the water.
Floors can display moist patches and staining, materials such as stone and brick are naturally porous and will soak up moisture like a sponge without the aid of a damp proof membrane or rising damp treatment. In a more modern building, a damp proof course is installed at the time of construction, however, when this treatment does not exist or becomes damaged the most common result is rising damp.
The result of this is damage to interior plaster and wall coverings. If left untreated it may cause rot and decay in floor joists and other interior timber that comes into contact with it, as well as causing more damage to the interior of the property.