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The most common reasons why windows leak when it rains

leaking window

Windows are a vital part of any home, providing both natural light and ventilation. However, during a rainstorm, windows can also become a source of water damage if they leak. There are a few different reasons why this may happen.

Failing Caulking or Sealant

One of the most common reasons for leaks is failing caulking or sealant. Over time, these materials can degrade due to exposure to the elements and general wear and tear. As they break down, they no longer provide a watertight seal around the edges of the window.

Cracks in Window Frame

Another potential source of leaks is cracks in the window frame. These can be caused by everything from age and weathering to impact damage. Even small cracks can allow water to seep through and cause problems.

Improper Installation

In some cases, windows may leak due to improper installation. If they’re not installed level or plumb, there may be gaps around the edges that allow water to get in. This is why it’s important to hire a professional for window installation.

Issues with Flashing

Flashing is a critical part of the window installation process. It’s a water-resistant material that’s used to seal the space between the window and the surrounding framing. If it’s not installed correctly or has failed, it can allow water to seep in and cause leaks.


In some cases, what appears to be a leak may actually be condensation. This can happen when there’s a significant difference between the indoor and outdoor temperatures. The warmer air inside the house condenses on the cold glass of the window, causing water to run down the glass. While this isn’t technically a leak, it can still cause water damage if it’s not addressed.

Warped or Damaged Windows

Finally, leaks can also be caused by warped or damaged windows. These may have been damaged by severe weather, impact, or simply age and wear. If the window is no longer level or square, it may not fit properly in the frame and allow water to leak in.

How to prevent your windows from leaking in the first place

Prevention is always better than cure, and this is especially true when it comes to window leaks. There are a few simple things you can do to help prevent your windows from leaking in the first place.

Firstly, make sure that your windows are properly sealed and weatherproofed. If you live in an area with high winds, consider installing window guards or shutters.

Secondly, ensure that your gutters and downpipes are clear and in good condition. This will help to prevent water from flowing back into your home.

And finally, keep an eye on the condition of your windows, checking for cracks or gaps that could allow water to enter. By taking these simple precautions, you can help to keep your home dry and comfortable all year round.

Khalil Chahine
Khalil Chahine

Khalil is the owner of Splendid Window Glass Repairs and has over 8 years experience as a glazier specialising in window glass repair, replacement and installations. Khalil takes great pride in his work and prides himself on providing an excellent service to all of his customers, no matter how big or small the job may be.