Penetrating damp is caused by water leaking through walls. This type of damp may move around within a building, but this is through horizontal movement rather than by travelling up walls (as is the case with rising damp). Penetrating damp is usually caused by structural problems in a building, such as faulty guttering or roofing.
Penetrating damp often shows up through damp patches on walls, ceilings or floors, which may darken when it rains. You’re more likely to get penetrating damp if you live in an older building with solid walls, as cavity walls provide some protection.
Condensation
Condensation is the most common kind of damp and is caused by moist air condensing on walls. It's mainly a winter problem, as at this time of year walls are much colder than the air inside. Condensation can be exacerbated by poor ventilation, and heating that comes on and off, as this allows warm, damp air to condense. The removal of existing chimneys and fitting air-tight double glazing can reduce ventilation. There are systems available to help improve ventilation, such as the Drimaster Heat positive input ventilation system. Discover how it performed in our first look review.