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Last updated: 20 May 2024

Why Are My Windows Leaking?

Why Are My Windows Leaking?

In most cases, leaking windows are caused by poor installation and/or the windows are old and key parts such as seals have degraded over time. If you have a problem with leaking windows, don’t ignore it. It will only get worse and if not addressed can cause significant damage to your home from mold, mildew and rot to problems with the foundations of the property.

There are several possible causes of leaking windows. Finding out what is behind yours is the first crucial step in getting the window repaired or replaced. Get in touch now to get free quotes from up to 4 trustworthy and highly recommended window installers in your area.

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8 Common causes of leaking windows

A note about condensation: Sometimes condensation on the interior of the windows can be mistaken for leaking. The condensation is caused by excessive moisture in the house, e.g. when the air is warmer inside than the air outside. If condensation occurs between window panes this may be because a seal between them is broken.

If you do not have an issue with condensation, here are 8 common causes of window leaking.

1. Poor installation

Easily the most common cause of a leaking window is that it was poorly installed. A window may look good to the untrained eye, but if it has issues such as breaks in the window flashing (a water repellent border of material around the window). In some cases, the installer may have used house wrap or building paper rather than proper window flashing. This will result in water seeping into the wall around the house.

2. Unlevel windows

If a window has not been correctly levelled it is likely to collect water. You can use a spirit level to check whether or not your windows are level.

3. Poor sealing

Windows are usually sealed with expanding foam which prevents window leaking but if too little is used it can create channels of air between the wall and window which can lead to leaking. It is important that your installer accurately measures the aperture and installs windows which fit exactly. It is not good practice to get windows which are too small and fill in the gaps with foam.

4. Missing or broken caulking

On the outside of the window at the seams there should be caulk(sealant) which is another barrier against water. If the caulk has gaps or cracks you may find leaks become a regular irritation.

Taking care of your windows can prevent issues with damaged sealing, understanding how to clean windows the right way, can help with this.

5. Bad glass seal

If you notice that water is leaking into the window but stays between the panes of glass it is likely that you have a bad glass seal. This may mean that water can make its way into the home but it is more likely that the windows will have lost the insulating gas which helps them keep heat inside and the cold outside in winter (and vice-versa in summer). This makes them less energy efficient and could increase your heating costs.

In many cases a paint seal around the glass can increase the level of protection. This is simply overlapping the paint very slightly onto the glass. It is not noticeable visually but it creates a protective membrane which seals the glass against moisture.

6. Missing overhangs

If your property does not have overhangs which drain water off the roof you may be getting a higher than average amount of rainfall hitting your windows. Similarly, the fascia boards above your windows should be angled to ensure the water is directed away from the window.

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7. Leaking walls

It’s possible that your windows are not the problem. If you can see stains at the top of the window frame the leak may be coming from your walls. You should check for gaps or cracks on the walls and re-seal if this is the issue.

8. Poor quality windows

Although it is relatively rare, it may be that the leak is due to a faulty product because of an error during the manufacturing process or damage during shipping or installation.

Replacing leaky windows

The best way to prevent windows from leaking is to get them installed by an experienced and highly recommended window fitter like those in our Windows Guide installer network. You can also choose to install windows with weather resistance features and materials.

If your windows are leaking and you would like a quote to get them repaired or replaced, send us an enquiry today.

We have a network of window installers right across the UK and to find approved installers in your area, all you have to do is complete our simple online form. This will only take a matter of minutes and once you’re done, you’ll get free quotes from up to 4 window installers based in your area.

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