Window condensation can appear inside, outside, or between panes. Some types of condensation are easy to fix, while others require a little more effort to address.

In this article, we’ll explain what causes condensation inside windows vs outside, when condensation is normal, and how to stop or fix window condensation. Let’s get into it.

Condensation occurs when water vapor sticks to a cool surface. Window condensation can be caused by high humidity, excessive moisture, extreme temperature fluctuations, or poor airflow inside the home. It can also be caused by old windows (that don’t offer good insulation) or windows with a broken seal.

Window condensation is common in homes, but it isn’t something to ignore. Condensation on the outside of windows isn’t usually a problem, but condensation between the glass is cause for concern.

Window condensation inside the home can be a problem, however it does not usually mean there is something wrong with your windows. This tends to be most common in the winter when outside temperatures are extremely cold. Condensation tends to build up on the bottom or edges of the glass, meaning there is too much humidity in your home relative to outside temperature and it’s collecting on the glass because it is the coldest point.

This is especially common during winter after cooking, showering, or drying clothes inside the house. It’s important to air out the property or run a dehumidifier to prevent damp issues and black mold if you are experiencing this issue.

Interior condensation is typically not a sign of a poorly insulated window, in fact it can be more common in new windows because they insulate better. When windows are better insulated they hold the heat in and the cold out better, leaving nowhere for the moisture to escape and creating a greater temperature difference from interior and exterior. The glass will always be the coldest point though, so it is where you will see the moisture build up.

Condensation on the outside of your windows is fairly normal in the summer when the humidity is high. It’s caused the same way as interior condensation, only now forming on the exterior because that is where the humidity is.

Condensation on windows in the summer usually only appears in the morning or overnight, when temperatures are at their lowest and relative humidity is at it’s highest. As the sun rises, it can disappear.

You should be concerned about window condensation when it appears between the glass on your windows. This is a sign that your window seals are broken, and the condensation is unlikely to go away unless you replace the glass.

This type of condensation is a major sign it’s time to replace your windows. It’s important to seek professional help quickly in these situations to prevent further damage. The glass is also not energy efficient once this happens as it means it has lost its seal.

Getting rid of window condensation isn’t always a quick fix. If there’s an issue with the insulating properties of your windows, you’ll likely need to upgrade your windows or get professional help to fix the problem.

However, there are some easy ways to remove condensation from your windows, which you can read more about below.

Ventilating a property regularly can stop condensation from appearing on windows. To improve ventilation, turn on exhaust fans in bathrooms or your kitchen, or open the windows occasionally to let air into the property. It’s a good idea to open windows when cooking, showering, running a tumble dryer, or drying clothes.

Using a dehumidifier can instantly decrease humidity in a home. Dehumidifiers work by extracting water from the air in the room it’s in, which can quickly remove condensation on the inside of windows.

You can simply wipe away excess moisture from an interior window to get rid of condensation using a soft, absorbent cloth. However, it’s important to remember that this isn’t a long-term fix, as moisture can quickly build up again after wiping.

You should also be careful to ensure water doesn’t seep into the windowsills or pool onto the window ledge after wiping it down.
This can cause long-term damage to the windowsills and disrupt the effectiveness of your insulation. It can also damage your window ledge and cause wood rot.

Single-glazed windows or old windows can cause condensation, particularly if the window seal is broken. While running a dehumidifier will remove water on windows inside the home, it will never fix the issue entirely unless the windows are replaced. Because condensation forms at the coldest spots, it will form much easier on single-pane glass that’s poorly insulated.

Upgrading windows to triple-glazed glass can fix condensation issues. Speak to a professional window installer to check your windows for issues and get a free estimate if there’s a problem that needs fixing.

Mold on windows from condensation is a serious cause for concern. Black spots appearing above your windows and around the sill or on the ledge mean there’s too much moisture around your windows.

This can be due to high humidity levels in your home or because of an issue with your windows – like a broken seal.

Mold on windows can be prevented by reducing inside window condensation. For example, by using a dehumidifier to reduce indoor humidity and quickly wiping away moisture on windows.

To get rid of mold on windows, you need to first wipe away any excessive moisture. Otherwise, the mold will quickly reappear. Spraying bleach, white vinegar, or a mold remover spray can instantly remove mold on windows caused by condensation.

Simply spray the area, leave it for several minutes to work, and then wipe the area with a clean cloth. Make sure you air out the room after cleaning by opening the nearby windows or using an air purifier.

A window seal is broken when moisture appears inside the window, as if it’s between the glass. When the moisture can’t be wiped off the window from the inside or the outside, you need to replace the glass or the entire window.

Should I Call a Professional?

To decide if it’s time to call a professional about your window moisture problems, use the following checklist. If the answer is ‘yes’ to any of the below, it may be time to call an expert:

• Your windows have condensation between the glass (a sign that the glass needs replacing)
• You have to run a dehumidifier constantly to reduce humidity (a sign that your window seal could be broken)
• Airing out the home doesn’t reduce humidity or condensation (as above)
• Condensation appears on your windows all year round
• Your windows are single-glazed (they may be poorly insulate and causing the condensation)
• You have black mold around your windowsill (this may have damaged your window seal)
• You want someone to look at your windows to check for damage

Window condensation can be normal, but it can also be a sign that your windows or the moisture in your home needs attention.
Check if your condensation issues are caused by a window issue by contacting our friendly team of experts today. We can provide tailored advice on what’s causing your condensation and provide a free estimate for any necessary fixes.