Damp penetration usually refers to any water that enters a building and moves through the walls horizontally, or from a higher to a lower level. It is usually associated with external construction defects. Penetrating damp may move about within the building in various ways but is not “rising damp”. Penetrating damp occurs as a result of problems with the fabric of the building that can allow water to leak into the walls or floors.
The first sign of damp penetration is often the appearance of damp patches on walls, ceilings or floors. These tend to grow or darken after periods of heavy or prolonged rain. The long term effects of water penetration can include damage to decoration and plaster, decay in exposed timber, and mould growth. Penetrating damp is most common in older homes that have solid walls. A new build property with cavity walls offers more protection against driven rain.