What causes condensation?

Interior condensation forms when excess moisture in the air comes into contact with a cold surface. When it is significantly colder outside than inside, condensation will form on the surface of a window as the water molecules quickly join together.

Unfortunately, condensation tends to be more prevalent in the winter season when it is colder outside, and the windows and doors are closed to retain the heat in occupied properties. Because of this, it is paramount when considering glazing that all projects must consider ventilation, this is key to removing any moisture build-up within the home.

Traditional single glazed units will of course have the most condensation appearing on the glass, as the glass is as cold on the inside as the outside. With the recent introduction of double and triple glazed units, condensation has been reduced. However, occasional condensation can still form, as described below.

Problems associated with interior condensation

If problems with condensation are not quickly fixed, serious problems can occur. Condensation can be detrimental to both the condition of a building, particularly its windows, and in the long term, it can have a negative impact on the occupants’ health. Some warning signs to watch out for include:

  • Paint peeling off timber windows
  • Patches of black mould on window frames
  • Wet patches on walls and ceilings
  • Changes in the health of inhabitants

Condensation can be serious. It is certainly something that should be addressed sooner rather than later. If you’re having problems with condensation, let’s take a look at some of the most effective ways to solve the issue.

How Can I Stop Condensation On My Glass Panels?

Does ventilation help?

If your windows or doors have vents, it's a good idea to keep them open to allow for proper air circulation. Additionally, make sure to keep the doors shut when using the shower, cooking, or boiling water, and use a fan to reduce the amount of vapor in the room.

How can I remove the moisture from the air?

Using an air-conditioned unit can help to dry the air in the room. By using a dehumidifier or a moisture eliminator it should remove the main cause of condensation.

Do plants have an effect on condensation?

Plants are a wonderful addition to any room but unfortunately, they add too much moisture into the air. If you want to avoid this happening it would be wise to move them to a more suitable well-ventilated room during colder seasons when external temperatures are significantly different from the internal temperature in the room.

close up shot of condensation on glass

Internal Condensation

With recent insulation requirements for glazing efficiency, the internal pane of the glass can have condensation issues. This is due to the temperature variation between the external and internal environment.

Water droplets occur depending on how much moisture there is in the home. For example, the steam from a kettle, drying washing, cooking, plants, or shower will naturally be absorbed into the air. When this water vapour comes into contact with a colder surface the air will be chilled.

Double and triple glazing can help to reduce the amount of condensation on the windows. However, it cannot completely eradicate the issue. If the air temperature within the room is low (not heated) and not well ventilated the air reaches a point when it becomes too saturated. This cooler air meets the colder internal glass and vapour will turn back into moisture. When this happens water droplets will appear on the glass.

External Condensation

Fortunately, when external condensation appears on the outside of the glass it is not a sign of poor performance. It is actually a positive sign that your glass windows, doors, or roof lights are doing a good job. In fact, the purpose for which they were designed.

With modern glazing efficiencies, maintaining a comfortable internal temperature, saving on energy costs, and meeting building regulations windows and doors are more thermally efficient.

The more highly insulated your glass is, the greater the likelihood of external condensation forming on the outside of the glass. With modern low/e (emissivity) glass heat is retained within the room and not lost through the glass. The internal panel is considerably warmer than the outer panel compared to single or old double-glazed units where the temperature differences are not as great.

close up shot of condensation on glass

Internal Cavity Condensation

Having condensation on the glass of your windows is perfectly normal, as pointed out above. However, having condensation on the inside of the cavity within the glass is not. If this happens unfortunately the glass cannot be fixed and will need to be replaced.

The manufacturer’s guarantee should cover this within the guaranteed period. New glass will need to be ordered and installed, outside of the guarantee this will be chargeable.