There are a number of causes for damp walls and ceilings. Inappropriate, non-breathable materials are one contributing factor, especially in older properties, along with poor ventilation and poor exterior surfaces like blown brick work. Rooms that are below ground level, such as basements, are also more affected by damp.
We find lots of customers have damp walls which have been coated in non-breathable gypsum plaster and vinyl based paints in an effort to waterproof the room. In the short term this might solve the damp issue by keeping water out, (by, for example, using a damp proof paint) but longer term, moisture becomes trapped under the surface and builds up, so the damp basement walls become more and more saturated.
A better way to treat damp walls is to use breathable building materials such as lime plaster and breathable coatings like limewash or Claypaint. This will allow any moisture trapped within the walls to naturally pass through the surface of the wall and help to regulate the humidity in the space.
Claypaint has an exceptionally high level of breathablilty and is a user-friendly alternative to limewash. It’s available in a wide range of colours with a host of other benefits. Being hygroscopic, the surface of Claypaint will change and the colour may deepen where it has absorbed moisture. When allowed to dry out naturally these marks should disappear, although in some cases, for example if there are salts in the walls, some staining may occur.