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Our windows serve multiple purposes, including letting light and air in while keeping moisture at bay. Yet, we often find mold growing on or around our windows, especially during the colder months. So why does this happen? And what can we do to fix it? Read on to find out.

Why Does Mold Grow on Windows During the Winter?

It seems counterintuitive – mold grows best in dark, warm places. So how come the parts of our home that specifically exist to allow light in seem to grow mold during the coldest times of the year?

The main cause of this growth is condensation. We turn up the heat to keep our homes warm as the weather gets colder. The disparity between inner and outside temperatures causes moisture to condense against the inside of a window. The condensation will cling to the glass, warm enough to welcome mold spores and give them a good place to hold or run down to the sill. If the water runs, it will pool and collect along the windowsill, again creating the perfect warm and damp environment for mold to start growing.

In both cases, the mold will grow and spread if not dealt with quickly. Not only will this look and smell unpleasant, but it will lead to a few other issues, such as:

Health risks for you and your family

Mold spores will infiltrate the air you breathe, which has the potential to cause severe health problems. Inhaled mold spores can cause various lung infections, and some people have undiagnosed allergies to them.

Potential damage to the windowsill

Even though they are tiny, mold roots will quickly burrow their way into the material of your window sills. If left alone, this can cause the material to weaken and crack, creating gaps that will destroy the water-tight nature of the windows. Air and water getting in will lead to further mold infestations and allow insects and other bugs inside. Air getting out will affect the efficiency of your home’s heating systems, increasing utility bills through wastage.

Damage to the walls surrounding the window

As the mold spreads, it will find its way farther into your home, affecting the very structure of the walls around the window. In extreme cases, this can completely obliterate the structural integrity of the whole window and lead to further infestations of mold throughout your home.

How to Get Rid of Mold on Your Windows

Fortunately, none of the above needs come to light, as there are many ways that you can remove the molds present on your windows. The DIY process requires a few tools and chemicals, most of which should be available at your local hardware store. It’s also a good idea to consult your local Davis County mold clean up expert if you have additional questions or concerns.

Surface Mold on Glass or Sills

Antifungal spirits and a damp cloth will effectively remove surface mold, disinfecting it to prevent any more spores from taking root. The same is true of vodka, which will kill mold similarly through a diluted solution scrubbed into affected areas. Another household option is to use one cup of bleach diluted in a gallon of water.

Rub it into the affected areas on sills or walls to allow the mixture to seep into the surface and kill any shallow roots. After you have left it for an hour or so, wipe down the affected areas with a dry cloth and allow it to dry by ventilating the area. This will help disperse any more mold spores that are put into the air, preventing them from landing again. Check back after a day to see whether the mold has gone, and reapply if necessary.

Deeper Growths in Sills or Walls

If you have found mold after it has had a chance to take root, removing it will not be quite as simple. As the mold roots have had time to sink below the surface, they will require much more soaking with stronger chemicals to ensure they are all effectively killed. If the growth is extensive, it’s best to seek an Utah mold clean up specialist.

In the most extreme cases, you must remove the sections of the wall or the sill to excise the infestation completely. This is only necessary if the surfaces are visibly warped or deeply damaged. You will need a professional if it is soft to the touch, spongy, or pliant. This will be especially problematic during the colder months, as gaps and weakened walls will lessen heat retention in your home.

Prevent Mold Growth During Cold Months

As with all problems around the home, the best method of getting rid of mold growth during the colder days is to prevent it from being able to get a foothold. If the mold doesn’t take root, it can’t weaken and destroy your windows.

1. Lower the Temperature

The colder months are not a time we consider air conditioning. Usually, we want to pump up the temperature as high as it will go to keep our homes as cozy as possible. However, keeping the air at a lower but comfortable temperature will prevent mold from having its ideal environment.

2. Dehumidify the Air

Keeping a dehumidifier handy will give you a quick way to lessen the overall moisture in your home. The less moisture there is, the less condensation can form. It will also pay to ensure all extractor fans in your bathrooms and kitchen are fully functional. This will prevent further buildup when the shower or bath is going or while cooking, further stripping mold of its power.

3. Go Green with Plants

House plants are a great way to purify your home’s air in winter without adding to your utility bills. It might take trial and error, as finding the best combination of plants to thrive in those cold months may take time, but it’s worth it for the aesthetic improvements alone.

4. Keep Up Air Flow

It can be tempting to make your home as airtight as possible during cold months, but this is just inviting a disaster. Mold can only grow if it can settle. Regularly opening windows for brief periods will sweep mold through and out of your home by ensuring your home has good airflow. If the air in your home is still, mold will be allowed to thrive.

Mold is a huge problem when maintaining homes, and our windows can be a prime source during cold periods. Take some time to keep your air clear, and your family safe, by preventing mold growth on your windows. Sometimes all it takes is ten minutes with a window open to prevent potentially costly damage from occurring.


If you have found mold growing on your windows in cold weather, it is essential to take immediate action. Mold can spread quickly in the right conditions and cause serious health risks. The best way to get rid of mold is to contact a disaster or restoration company specializing in cleaning up after water damage and mold removal.

4 Ways to Get Rid of Window Mold Infographic