What Is Penetrating Damp?

Penetrating damp occurs when moisture seeps into the interior of a building through external walls, roofs, or windows. This can be caused by leaks, poor construction, or damaged building materials.

Common signs of penetrating damp:

1. Wet or Damp Patches on Walls and Ceilings

Stains, water marks, or patches on walls and ceilings, often darker in color (brown or yellow), can be an indication that moisture is getting through from the outside.

2. Peeling or Bubbling Paint/Wallpaper

Damp areas can cause paint to peel or wallpaper to bubble, especially in areas exposed to rain or high moisture levels.

3. Mold Growth

Persistent dampness often leads to the growth of mold, which can appear as black, green, or white spots, particularly in corners or around window frames.

4. Musty Odors

A damp or musty smell often accompanies penetrating damp, especially in rooms that are poorly ventilated or have high humidity.

5. Efflorescence (White Powdery Deposits)

Salt deposits that appear as white powder on walls or surfaces, often around damp patches, are a sign of moisture moving through the structure and evaporating.

6. Damaged or Deteriorated Woodwork

Wooden fixtures like doors, window frames, or skirting boards can begin to rot or swell due to prolonged exposure to moisture.

7. Cracked or Broken External Walls

Cracks in external walls, faulty pointing, or damaged mortar joints can allow water to enter the building, leading to signs of penetrating damp inside.