Table of Contents
Key Takeaways:
External condensation is normal and typically not a cause for concern.
Energy-efficient windows may generate more external condensation.
The benefits of A-rated windows outweigh the negative of external condensation.
Condensation on the outside of windows usually clears on its own.
It is typically seen overnight and in the morning.
Condensation on the outside of windows is usually normal and nothing to worry about. It typically occurs in the early morning or overnight and does not typically signal a problem with your windows. In fact, it could be a sign your windows are doing their job of insulating almost too well. External condensation usually clears up as the glass warms up through the day.
In this blog, we’ll explain a bit more about what causes condensation inside and outside your windows, provide tips to reduce it, and discuss when it could be a cause for concern.
What Causes Condensation on the Outside of Windows?
Condensation is water vapour that condenses on the more humid side of a surface. With windows, this can be the inside or outside of the glass or even between the panes.
It is formed when an object (such as a glass window) reaches its ‘dew point temperature’, with water vapour from the air condensing on the surface.
The dew point temperature is the temperature at which the maximum amount of water vapour is achieved, known as saturation or 100% relative humidity. The dew point temperature can’t be higher than the air temperature. The dew point temperature varies depending on humidity and air pressure.
Why It’s Common on Modern Double & Triple Glazing
There are numerous benefits to installing new, energy-efficient double or triple-glazed windows. However, one of the drawbacks is condensation on the external glass. This is a particular issue in the UK’s changeable climate.
Some new double and triple-glazed windows are so effective at retaining heat in the home that condensation appears on the outer pane of glass. The low-emissivity inner panes of glass stop heat from travelling out and warming the outer panes, so the temperature of the outer glass stays cooler and moisture forms externally.
When Does External Condensation Usually Appear?
Some external condensation is natural during the summer months, when it is humid outside, and your house may be cool until the sun warms it through. It can also occur in Spring and Autumn when the temperature is changeable, and on clear, calm nights.
It is most likely to occur when windows are shaded from the sun or lack airflow.
This condensation typically occurs in the early morning and should clear up by midday as the sun evaporates the water vapour.
This condensation usually occurs most clearly in the centre of the glass, becoming less visible closer to the insulated frame.
Outside
- Usually normal
- Mostly cosmetic
- Usually clears by midday
- If it doesn’t clear, it could be an internal humidity issue
Inside
- Not normal
- Often, indoor humidity or ventilation issues
- Can cause mould and mildew
- Can be prevented
Internal condensation is a bigger issue, potentially causing serious damage and health problems. We have gathered some tips and tricks for reducing condensation in your home, including introducing specific house plants, in a previous blog.
Between the Panes
- Not normal
- Likely due to a seal failure, enabling water droplets to form when the hot air hits the space between the glass panes
- Window repair or replacement is needed
The good news is, as long as it’s not a big crack, resealing the window is a relatively quick and low-cost fix. If the windows are still within their warranty, you should not have to pay for the seal repair.
Can You Prevent Condensation on the Outside?
You cannot always prevent external condensation, but there are a few ways you can reduce it.
- Improve airflow – ensure your windows offer enough ventilation.
- Increase sunlight exposure – remove any obstructions.
- Keep your glass clean – wipe away any external condensation.
- Treat your windows with a water repellent – this will stop the water vapour gathering on the surface and cause it to run off.
- Trim any nearby foliage that could be dripping and contributing to the moisture. It will also enable the sun to reach the window faster.
- Increase the temperature inside your home – e.g. turn off any fans or cooling devices for part of the day to help balance the interior and exterior temperature.
You should be aware that this is a trade-off – less external condensation means more heat loss from your windows.
External condensation can obscure your view, but as long as it clears reasonably quickly, it should not be damaging to your window.
It is up to you to decide if maintaining clearer windows in the early hours is worth a reduction in your insulation and energy efficiency.
When Should You Be Concerned?
External condensation is largely an aesthetic issue, but you should be concerned if:
- It happens more frequently than is normal
- The external condensation doesn’t clear
- There’s internal condensation
- Condensation occurs between the panes
- There’s damp or mould indoors
- There#s damage to the frame or external glass
Frequent external condensation can point to a high humidity problem within the home. If you think this is the case, you can hire a home inspector to check where the moisture is coming from.
Conclusion
Condensation on the outside of windows is a common complaint from homeowners, but in most cases, it is nothing to worry about. We hope this blog has set your mind at ease and given you some tips on dealing with condensation on your external windows.
Energy Efficient Windows at Manchester Window Factory
At Manchester Window Factory, we are experts in providing and installing the highest quality A-rated UPVC, aluminium, and timber windows. We can talk you through your options and offer a free, no-obligation quote for your consideration. We also offer a pay-monthly scheme to help you spread the cost. If you would like further information on any of our products or services, please don’t hesitate to get in touch.
We look forward to hearing from you!
How to Get in Touch
To request a free brochure, you can call us on 0161 976 4739, use our contact form or chat with us via the chat button at the bottom right of this website. If you live locally, you can also visit our Altrincham showroom, and check our contacts page for up-to-date opening hours.
We look forward to hearing from you!
FAQs
No, typically, condensation on the outside of windows is a short-lived natural phenomenon due to the outside of the window being colder than the inside.
Early in the morning is typically when it is coldest, and the cold air hits the outer pane when it has radiated most of its heat away. There is also typically more moisture in the air at this time of day.
Whereas condensation on the inside of your windows is a sign that your windows may not be functioning properly, external condensation can mean the opposite. Your glazing and frame are doing such a good job of stopping heat escaping that your windows are getting colder on the outside.
In most cases, you won’t need to replace or repair your windows, assuming external condensation is your only issue.
The recommended humidity level for UK homes is 30% to 60%. Lower than 30% causes dry air, leading to a host of health issues such as dry skin, hair and eyes, plus damage to walls, floors and furniture. However, any higher than 70% and you are at risk of muscle cramps, dehydration, fatigue and respiratory flare-ups, plus damp and mould.
There are a few reasons you may see external condensation on only some of your windows:
- Wind exposure – windows exposed to more wind are less likely to develop external condensation because the moisture doesn’t settle on the glass.
- Better insulation – if you have different windows in some rooms
- Slight temperature variations can affect different parts of the window, creating ‘border condensation’
- North-facing windows get less sun than south, west or east-facing windows, keeping their surface temperatures cooler.
- Likewise for windows in shaded locations.