Honest Jon’s technical blog

Condensation Part 1: What is condensation?

Picture if you will, an ice cold drink on a hot summers day. The glass is beaded in droplets of water, just waiting for you to pick it up and quench your thirst. Lovely isn’t it? Not so lovely when the same process - condensation - forms in your home. Even worse if this is left to fester, eventually leading to unsightly and unhealthy patches of mould.

Condensation is the result of humidity levels in the atmosphere reaching saturation point; often referred to as dew-point.  When this type of atmosphere comes into contact with a cold surface, water vapour condenses onto the surface. The colder the surface, the quicker the condensation forms.

There are essentially two types of condensation in the home; Surface condensation and interstitial condensation. Surface condensation will be familiar to everyone as it occurs in every home. It’s the result of breathing, cooking, heating, washing, drying clothes etc - all the day to day activities to be found in millions of homes across the UK. This type of condensation forms on non-porous surfaces such as window panes and can make the household atmosphere dank and musty if not ventilated adequately. It can also lead to staining which will eventually require redecoration, so is inconvenient and costly.

Interstitial condensation, which is most often found in new build properties, forms within the very fabric of the building as a result of the significant amount of moisture released through excavation and the building works. When the building is completed, the moisture can remain trapped in the building, leading to condensation. If not dealt with, it can result in serious structural damage such as timber decay and can have a detrimental effect on insulation.

Condensation is not just a nuisance; it can lead to significant structural problems, costly redecorating and can even affect the health of the occupants if left to develop into mould.