Why Do I Get External Condensation On My New Windows?

When you pull back the curtains first thing in the morning at certain points of the year, you will often be greeted by the sight of external condensation on your windows.

Double Glazing

It’s something you would expect to see on the outside of old windows, but not necessarily on the exterior of brand-new energy efficient windows.

In this instance, a customer’s immediate thought may be to get in touch with their window supplier to report the issue, but in fact, it’s a perfectly normal thing to happen – the windows are not faulty!

Believe it or not, it’s a good sign as it shows that your new windows are doing an excellent job of preventing heat loss and keeping more of it indoors.

The reason condensation forms on the outer pane of a modern double or triple glazed unit is because the temperature of the glass has dropped below the external dew point temperature and doesn’t get warm as heat cannot move across the unit.

Unfortunately, nothing can be done to stop it. But it will only happen infrequently, typically from time-to-time during the spring and autumn months.

Just use a towel to wipe it all away or be patient and wait for the sun to come out and the temperature to rise to make it evaporate.

If condensation forms between the two panes of glass on the inside of a new double or triple glazed sealed unit, then yes, there is a major problem and the window unit has likely failed.

All double and triple glazed windows sold by Trent Valley Windows satisfy current Building Regulations, so this scenario is an impossibility.

When in discussions with our team about buying new windows, you will be told about potential external condensation as we don’t like to keep secrets from our customers.


Beginning your home improvement journey can be daunting. With new terminology and so much choice out there, it can be daunting – and not to mention alienating. To help, we’ve put together this FAQ section and answered some of your key questions.


Want to speak with an Advisor? Give us a call on 0115 959 8000

Our friendly team will be pleased to help with any questions you may have.
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