Rising damp is as a result of porous construction materials sucking up water from the soil.  Water will rise up the wall where there is a failure or lack of damp proof course.   The water can rise to approximately 1m from ground level and will often leave a characteristic horizontal line known as a tide mark.  Distress to the internal plaster, peeling and blistered paint/wall paper and signs of rot to skirting boards and timber panelling are other indications of rising damp.  Timbers adjacent to or built into damp walls, such as floor joists are at increased risk of decay.