Can blown windows cause damp? SAM Conveyancing explains how to spot the signs
Worried that your house has blown windows?
This can lead to condensation, damp and ultimately mould problems. Dealing with this is an extra cost you'll want to avoid.

An experienced surveyor will be able to uncover these for you. All our fees are fixed and we offer same week availability, with arranged access.
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Can Blown Windows Cause Damp?

(Last Updated: 27/01/2023)
5 min read
Key Takeaways
  • Double glazed windows are more efficient in terms of heat retention.
  • Condensation is often formed on single glazed windows, although they can also show up on double glazed ones. This is often a sign of blown windows.
  • You can temporarily fix the problem, but in most cases you will need to replace the sealant or the actual windows.
  • When buying a house, your Level 2 and Level 3 surveys will spot any signs of double glazing failure.

When buying a house, it is essential you check for any potential risks to your investment. Factors like whether your windows are single glazed or double glazed can affect you once you move in. Single glazed windows are really common in a lot of properties throughout the UK, but they are less efficient in terms of heat retention and they are often affected by condensation.

Double glazed windows, however, keep you home warmer during the winter and cooler during the summers. Double glazed means that your windows are made out of two panes of glass, separated by a spacer bar.

An air gap is created in between the two panes, which prevents heat loss through double glazing windows. Although they are believed to be more efficient, the sealant in between those panes can be damaged, which leads to what is known as 'blown windows'.

Do blown windows cause condensation?

Yes, condensation is the biggest indicator of blown double glazed windows. As a result, windows tend to become foggy or cloudy. This is caused by a gap forming in between the panes, caused by either a damaged sealant or a defect to the actual glass panes.

So, can blown windows cause damp? If left untreated, yes, the condensation can lead to damp and even mould problems.

How do you tell if a double glazed window is blown?

  • Condensation
  • Rotten window frame
  • Draught
  • Water seeping through the frame
Signs of double glazing failure may not always be visible. For example, in the summertime, sellers can try to hide damp problems or they can paint over mould/damp affected areas. We always recommend getting a surveyor to check for this issue, as they are trained to recognise signs of blown double glazed windows.

Your level 2 or level 3 survey should uncover this. We discuss the difference between the two in our article - What Is The Difference Between Level 2 and Level 3 Survey?

Are blown windows a problem?

Blown windows are a problem, as they can cause condensation. If left untreated, this can lead to damp and mould forming inside the property, which is toxic for you and your family.

Another factor you need to weigh in is heat loss through double glazing windows. Whether or not can blown windows cause damp, an increased energy bill is something you'll want to avoid, especially in the cost of living crisis.

An indicator that windows can cause problems in the future is the absence of a FENSA certificate. Windows which have been replaced after April 2002 require it, as this attests that the work has been carried out by a member of the Competent Persons Scheme, and therefore it complies with all Building Regulations.

If the sellers chose to replace the windows themselves, they will not be able to provide you with this, so you should make sure that the work is still compliant. The best way to know if there's cause for concern is to get an experienced surveyor to check. They will be able to identify any possible risks.

How do you tell if a house has a damp problem?

  • Damaged internal decoration – Damp or discoloured tidemarks on internal walls;
  • Damaged plaster – Disintegration, salting or blistering;
  • Rotting skirting boards or floor boards – wet rot with decay;
  • Localised dampness – Dampness on walls rarely exceeds one metre above ground level, but may go much higher in extreme cases
If you suspect you have a damp problem, you can get a damp and timber survey to check. If that is the case and the problem is severe, you will need to act fast, as this can devalue your property.

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Laura Cristian - Digital Marketing Assistant - Meet the team - SAM Conveyancing
Written by:
Laura has a talent for data analysis and fact-finding. She is an advertising graduate with a broad range of skills in the web marketing field within conveyancing sector. She works closely with our panel of solicitors and surveyors to understand our clients' needs and challenges and to write the most valuable content for you.
Andrew Boast of Sam Conveyancing
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Andrew started his career in 2000 working within conveyancing solicitor firms and grew hands-on knowledge of a wide variety of conveyancing challenges and solutions. After helping in excess of 50,000 clients in his career, he uses all this experience within his article writing for SAM, mainstream media and his self published book How to Buy a House Without Killing Anyone.

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