How To Identify and Treat Condensation


What is Condensation?

Condensation on Glass

Condensation is surface moisture.

It predominently occurs on walls and ceilings, particularly in kitchens and bathrooms, and is the most common form of damp occuring in buildings. 



What Causes Condensation?

Moisture in the air is caused by numerous everyday activities such as breathing, cooking, bathing, washing and drying clothes and the operation of heating sytems. Condensation occurs when warm air comes into contact with cooler air or a surface with a lower temperature. Therefore, condensation is normally found in areas of a room with either a lower temperature or poor ventilation, for example, on windows and external walls. The temperature change results in air moisture 'condensing' from its gaseous state into a liquid state, resulting in condensation. 

How to Identify Condensation:

Condensation is normally best identified as small beads of moisture on non-absorbant surfaces such as windows, vinyl wall coverings or ceramic wall tiles.

However, condensation also occurs on all surface types and can be difficult to notice until it results in greater damage such as mould growth, paint peeling and wet rot. 

Therefore, to make a definitel diagnosis of condensation is not always easy. To do this, take readings using a damp detector from every room, in every level of the property, so these can be compared. An assessment of the external features should also be made in order to identify any contributing factors, for example a solid north facing wall exposed to the elements may be a 'colder' wall and more susceptible to condensation, and any alternative causes of the damp, such as falling damp or penetrating damp. See SkilldBuild's guide on How To Identify Which Type of Damp You Might Have for more information.Mildew Mould Growth Caused By Condensation

Problems Caused by Condensation: 

  • Peeled paint and wallpaper.

  • Flaking and damp plasterwork.

  • Black mould/mildew growth on walls and ceilings, which can adversely affect our health.

  • Musty smell.

Unsuitable Solutions to Condensation:
  • Ignoring the problem. This is likely to result in significant damage to your property, such as the problems listed above.

  • Insulating and warming the house. This will NOT solve the condensation problem. Unless the moisture content of the air is kept low (about 65-75% relative humidity) condensation will form on the coldest surface.

  • Redecorating over any mould created by condensation. This will not work since it is very likely to regrow through the paint or paper. See our How to Identify and Treat Black Mould (Mildew) guide for further information on redecorating areas affected by mould.

Solutions to Condensation:

  • Control the relative humidity of the house. The heating will need to be balanced with ventilation, or a dehumidifier can be used. This is acheived more easily throught the use of a hygrometer (which measures the relative humidity of the air). Moisture is reduced through constant circulation of gently pressurised air that expels stale humid air from the property.

  • In order to facilitate the circulation of air in the property, it may be advisable to install trickle vents.

  • Affected walls and ceiling should be dried out pror to redecoration.

  • Where surfaces are affected by black mould (mildew), use mould steriliser and killer, to clean and kill the spores before attempting any redecration. For more information, see our How to Identify and Treat Black Mould (Mildew) guide.

  • All paint redecoration should include an anti-mould additive to prevent regrowth of the mould. (Anti-mould paints are available, however, it is more cost effective to supplement standard emulsions with fungicidal additives to protect against further mould growth).

Simple Tips to Help Combat Condensation:

  • Keep furniture slightly away from the walls to allow free flow of air around the room.

  • Do not overfill cupboards, again to allow air flow.

  • Ensure that the loft insulation is not blocking the ventilation provided by the gap between the facia boards and the house wall, or purpose made vents.

  • If you are allowed, install cavity wall insulation.

  • Where possible, get the heating thermostatically controlled.

  • Externally ventilate tumble driers.

  • Install extractor fans in kitchens and bahrooms.