What to do about condensation on Double-Glazing Windows


One of the many reasons we install double glazed windows and doors is energy efficiency. From time to time, condensation, or formation of dewdrops on the inside or outside of the window is observed. Keeping in view the UK’s climate i.e., wet winters and high humidity levels, condensation is a usual phenomenon. 

What is condensation in double glazing?

Condensation is the formation of dewdrops which occurs when water vapours in the air come in contact with a cooler surface. A double-glazed window is composed of two glass panes separated by each other with air entrapped in between them. Condensation can occur on the outside, inside, or between these glass panes. 

This article aims to address the main causes of condensation in double-glazing and ways to prevent or eradicate it. 

Why is condensation bad?

Condensation on the window does not necessarily mean it is faulty. This would depend on where the condensation is on the window.

You will be surprised to know that condensation on the inside or outside of the window pane is actually a good sign that your double-glazing is working properly in keeping warmth inside and cold outside.  

However, if condensation occurs in between the glass panes, it indicates that the sealant of the window unit is damaged thus causing heat loss. This kind of condensation is bad because it reduces the lifespan of a window and if it is not dealt with properly, it can cause health issues. In extreme cases, black mould can grow within the windows and its spores can spread in the air causing breathing difficulties.

Condensation on the inside pane of the window

This most likely happens because of too much humidity and too little air circulation in the room. It is inevitable in washrooms and kitchens where there is more moisture and humidity. This kind of condensation can be eliminated by some simple DIY tips.  

DIY tips to remove internal condensation:

  • Increase ventilation: The best way to reduce internal condensation is by increasing air circulation that will decrease moisture and humidity in the room. Try to open the windows for some time in the day to allow air circulation which can help reduce humidity inside.
  • Reduce moisture: Little changes in the living can have a huge impact on the overall moisture in the house. For example, avoid drying clothes indoors or over the radiators. 
  • Use a hairdryer to clear condensation: It is a short-term fix and not a permanent solution, but it can help remove internal condensation.
  • Invest in a dehumidifier: It can absorb excess moisture from the house and can help prevent condensation on the windows.
  • Use Extractor fan: Use an extractor fan in kitchens while cooking and bathrooms after taking shower to remove moisture-rich air. 

Condensation on the outside pane of the window

If this happens, it’s a sign that your windows are working perfectly and are thermally efficient. It’s not a sign of anything wrong. However, it can be troublesome to have limited visibility until the condensation clears away. 

Condensation in the air gap between the two panes of the window

There can be multiple reasons behind condensation between the two panes of a window:

  1. Over time, the seal around the window unit can degrade or crack. This allows the warm air inside the room to invade the air gap and meet a cooler surface area resulting in condensation.
  2. Sometimes, the window frame can also crack and allow water droplets to gather inside the air gap. 
  3. Another reason can be a faulty space bar. Most double-glazed windows come with a spacer between the two window panes which is capable of absorbing any moisture in the air gap. If this spacer material becomes saturated with moisture, it cannot absorb more water, and then any possible moisture breach will appear as condensation.

Of course, condensation is never desirable, and to fix this issue, we need to figure out the cause to determine the solution. 

Solution No 1 – Repair:

If the window frame is in good condition, you may only need to replace the sealed unit. In most cases, a hole is drilled in the sealed units and a special drying agent is pumped inside to suck all the moisture. Sometimes, an anti-fogging agent is also used to prevent further moisture build-up before the unit is sealed again. 

Solution No 2 – Replacement:

Though it’s the more expensive route to take, it’s the best one for the long-term value for money. 

First, check if your windows are under guarantee then you should directly contact the installation company and report the problem. If the seal or unit is found to be defective, they should replace it for free. 

Fitting A-rated windows reduce the likelihood of condensation by decreasing heat loss from the house. Replacement is also a good time to redecorate your house by making small changes in window designs. 

To prevent condensation within the air gap, you should check the sealant regularly by running your fingers along the edges and see if you feel any breakages. If you have any other concerns related to condensation in your double-glazed windows and need an expert opinion, contact the windows installation company to know more. 

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