Windows are essential to any home, providing natural light, ventilation, and a view of the outside world.

However, they can also be a source of problems if the window starts to leak. Window leaks can lead to many issues, from increased energy bills to significant damage to your home’s structure. This article will explore how to tell if your window frames are leaking and what you can do about it.

Understanding the Causes of Leaking Windows

Before we delve into how to identify a leaking window frame, it’s important to understand why windows leak in the first place. The primary reason is usually due to poor installation or ageing. Over time, the sealant around the window frame can deteriorate, allowing water to seep in.

Another common cause is damage to the window itself. For example, cracks in the glass or frame can allow water to penetrate, resulting in water leaks. Extreme weather conditions in some parts of Western Australia can also contribute to window leaking.

Effects of Window Leaks

Leaky windows can lead to a variety of problems. One of the most immediate is an increase to your energy bill. Windows are designed to provide insulation, keeping your home warm in winter and letting in cold air in summer. They can let in drafts and air leaks when they leak, forcing your heating or cooling system to work harder.

Over time, leaking windows can also cause damage to your home’s structure. Water seeping in can lead to mould growth, rotten wood frames, loose tiles, sagging drywall and even damage the walls and floor around the window. This can be particularly problematic in older homes, where the damage may be more extensive and costly. Leaking windows can also leave your home with a musty smell.

How to Tell If Your Windows Are Leaking

Now that we understand why windows leak and the problems a window leak can cause, let’s look at how to identify window leaks. These are the several signs to look out for:

Visible Water Damaged Caulk

The most obvious sign of leaking windows is visible water damage. This could be water stains on the walls or floor around the window, peeling paint as the leak dries, or even visible mould growth. If you see any of these signs, your window is likely leaking.

However, not all water damage is immediately visible. In some cases, the water may be seeping into the wall cavity, causing damage that isn’t immediately apparent. If you suspect this is the case, it may be worth getting a professional to assess the situation.

Drafts and Temperature Changes

Another indication of window seal failure is cloudiness between the panes of glass or a noticeable draft or change in temperature around the window sill.

Unlike older storm windows, newer thermal windows have minimal gaps between the glass panes. Thermal windows use insulating noble Argon gas to maintain consistent temperatures. In both newer and older windows, there should be no foggy windows or moisture between the panes. If you feel a cold breeze coming in around the window on a windy day, or if the area around the window feels noticeably colder than the rest of the room, the window is likely leaking.

If the glass seal around the window fails, moisture can accumulate between the panes of glass. This often appears to homeowners as cloudiness or dirtiness that cannot be cleaned. You might also notice moisture buildup between the panes (different from normal condensation, which indicates the window is working correctly).

Although your window may not be leaking yet, cloudiness is a clear sign that the window seal has failed. Eventually, the window will begin to leak, potentially causing damage to your home’s walls, floors, and surrounding areas. Remember that drafts can also be caused by other issues, such as gaps in the insulation or problems with the window’s installation. If you’re unsure, it’s best to get a professional opinion.

What to Do If Your Windows Are Leaking

If you’ve identified that your windows are leaking, the next step is to address the issue. The best course of action is a visual inspection to determine the leak’s severity and the window’s condition.

Repairing Leaky Windows

In some cases, it may be possible to repair the leaky window. This could involve resealing the window frame, replacing damaged parts, or cleaning the window’s drainage channels. If the leak is due to a crack in the glass panes, it may be possible to fix the glass rather than replacing the entire window.

However, remember that repairs may not always be the best long-term solution. If the window is old or has common signs of deterioration, it may be more cost-effective to replace it entirely to prevent future damage.

Replacing A Leaky Window

If the window is leaking and is beyond repair, or if the cost of repairs would be close to the price of a new window, eventually it may be best to replace the windows. New window flashing or vinyl windows are more energy-efficient and replacement windows can improve the comfort and value of your home.

When choosing new windows, consider factors such as the window’s energy rating, the type of glass, and the exterior frame material. It’s also essential to ensure that the window is installed correctly to prevent water leaking through in the future.


Leaky windows can be a significant headache, leading to increased energy bills, potential damage to your home, wood rot and mould growth. However, by knowing how to identify a leaky window and understanding your options for repair or replacement, you can address the issue effectively and protect your home.

Remember, if you’re unsure about the condition of your windows or the best course of action, it’s always best to consult a professional. They can provide expert advice and ensure that your windows are in the best possible condition to keep your home comfortable and energy-efficient.