12 March 2022 - 8:13, by , in Wall leakages, No comments

Moisture and ventilation problems are usually the cause of condensation within a building. In most cases, it is not the result of a building defect. Moisture is trapped inside buildings with inadequate ventilation, leading to condensation problems.

Whenever warm air is in contact with a cold surface, like a wall or a window, it condenses. Poor ventilation can cause condensation to form in buildings, which is the most common cause of dampness. A home can be damaged by mould if condensation damp is left untreated. During the colder winter months condensation tends to be more noticeable.

Often, condensation occurs at low levels where the surface of the wall is coolest, starting in a corner and then spreading along the length of the wall. At first glance, this may appear to be rising damp.

Condensation is caused by excess water vapour in the air, which can’t escape. As well as a lack of ventilation, condensation can be caused by poor insulation or inadequate heating in the home.


wall leakage wall leakage

Image: Condensation forming on internal walls.

Warm air carries water vapour with it – the warmer the air, the higher the moisture load it is able to support. On contact with cooler surfaces, the moisture in the air condenses to form dampness or water droplets. This can sometimes be mistaken for wall leakage, when in fact the accumulated moisture is from condensation.

Window glass, colder surfaces on walls, openings around external doors and windows, and where floors and ceilings meet are the most likely places to experience condensation.

Often, condensation occurs in areas where natural air circulation is less or restricted, such as beside or behind furniture that is placed against an outside wall – or inside cupboards. Damp will begin to damage the area affected and patches of black mould growth can appear.

If you use humidifiers or dry clothes inside, most buildings will have some condensation. Showering, cooking, and bathing create higher levels of moisture in the air since warm air contains more moisture. When this warm and moisture loaded air come in touch with surfaces that are cooler, such as windows, cool walls or metal, the air temperature drops and the water vapour condenses into water droplets.



Common signs of condensation are

  • Damp walls with blistering paint
  • Damp windows
  • Droplets on the surface
  • Damaged and peeling wallpaper
  • Musty smell
  • Black mould growth along the edges of windows, skirting boards and wall to floor and wall to ceiling joints.
  • If the dampness has a tide mark on the wall, the dampness may be caused by rising damp or penetrating damp, leaking pipes or faulty roof.


Treating condensation

If the cause of the damp has been identified as condensation, the cure may be as simple as installing a good quality ventilation system that encourages the movement of the air from the inside if the building to the outside. Control the relative humidity in the building through the use of extractor fans in kitchens and bathrooms during and after cooking and bathing.

Ensure that there is adequate ventilation.  Cross-ventilate if possible. Trickle ventilation in windows works well in reducing the problems associated with poor ventilation, such as condensation. A trickle vent is a small slot/opening in a window or building envelope component, that allows small amounts of ventilation through a window and/or door when it is closed.

Wherever installation of a ventilation system is not feasible, using a dehumidifier together with a fan will help control the humidity level in the affected room.

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