In most cases, the source of penetrating damp comes from outside the building. External moisture finds its way into the property, often in the form of water ingress, allowing the damp to thrive. At Apollo Damp Proofing Ltd, in Beckenham, Kent, our team use many years of experience in the industry to advise and act on examples of penetrating damp.
One of the most common causes of moisture entry is exterior walls with render that has cracked, allowing for water to ingress to the inner walls. Where the exterior walls are made from bricks, the brickwork may have mortar missing or badly decayed brickwork. Other factors may include leaking or damaged guttering or damaged roofs that have allowed water to ingress through cavity walls. Other points of entry include where chimneys have been removed and down chimney pots that have not been capped.
Penetrating damp will cause random wet patches to appear on the inner walls, usually at higher levels. There may also be yellow staining marks where the wall has dried after being wet from rainfall. This staining will come from the plaster. Below you will find two different examples of penetrating damp:
The wall will look darker in places and may have staining marks.
Wet patches may form, or you could see a complete wet patch at any level.