Household mold can grow on a variety of surfaces and objects, from walls and windows to clothes, books, and toys. Over time, an unremedied mold issue in your home can damage your property and belongings and pose serious risks to your family’s health.
The wet winter season is one of the most common times to discover mold growing in your home. This article guides you through the indoor places you’re most likely to find mold in the winter and what you can do to prevent it.
Why Mold Grows in the Winter
Mold is a type of spore-producing fungus that can grow in both indoors and outdoor environments. These spores spread by floating through the air, and begin to grow when they land on a damp surface or object.
So why does mold grow in our homes during the winter? Well, mold spores thrive in moist, warm environments. Winter brings lots of moisture with extra rain, melting snow, and ice. The colder months also mean higher temperatures in our homes due to indoor heating.
Mold spores exist in all indoor environments. While there’s no way to prevent spores, there’s a lot you can do to ensure your home is not a friendly environment for them to land and begin to grow.

Where is mold most likely to grow?
Mold spores can enter your home through open doors and windows or through your home’s ventilation systems. They may also enter by attaching themselves to clothing, shoes, pets, or other vehicles. Mold spores can only begin to grow and thrive in conditions that contain sufficient moisture and a source of nutrients. That’s why dry, exposed areas of the home tend to be free of mold.
During the winter, mold is most likely to grow in basements (especially if leaking or flooding has occured), on windows where condensation has built up, and in areas with poor air circulation, such as behind walls or in closed closets or attic spaces. Mold spores also grow on objects with high cellulose content.
Here are the places and objects in your home where you’re most likely to discover mold during winter:
- Walls and wallpaper
- Roofs
- Windows and sills
- Pipes
- Cardboard
- Wood
- Ceiling tiles
- Insulation
- Upholstered furniture
- Clothes
- Books
- Toys
How to Prevent Mold Growth
The key to preventing mold from growing indoors, especially during the wet winter season, is controlling moisture and keeping your home as clean and well-ventilated as possible. Here’s what you should do:
Keep Humidity Low and Air Moving
Mold naturally thrives when there is moisture in the air and on nearby surfaces. Controlling household humidity is one of the best ways you can prevent mold from growing. That’s because, if the air in your home is dry, mold spores are less likely to land in a spot where they have enough moisture to begin to grow.
The Environmental Protection Agency (EPA) recommends keeping the humidity level in your home below 60%. Here are a few ways to lower the humidity level in your indoor spaces:
- Take cooler showers.
- Don’t leave wet clothes and towels sitting in laundry baskets.
- Avoid laying fabric mats in areas often exposed to moisture, such as bathrooms and basements.
- Move houseplants to a well-ventilated area.
- Invest in a dehumidifier.
Keep Mold-Prone Areas Dry & Clean
Regularly cleaning all mold-prone surfaces and objects in your home can help prevent mold from building up. Focus on windows and sills, corners in your kitchen, shower, and bathroom, and any areas where leaking or flooding happens. Wash and thoroughly dry bath mats, kitchen and bath towels, and other fabrics that absorb moisture. When you clean your bathroom, kitchen, basement, or other area frequently exposed to moisture, consider using products designed to kill mold.
Not only is it important to maintain a dry and clean environment indoors, but proper maintenance of the outside of your home, including gutters, outside window sills, sheds, and drains can drastically help reduce the risk of leaks and the buildup of moisture.
Repair Leaks Quickly
It’s a good idea to regularly check your gutters, drains, basement areas, and any exposed pipes in or around your home for leaks. Areas where leaking or flooding has occurred provide a unique opportunity for mold to take hold and begin to grow quickly. That’s why identifying and repairing leaks when they occur is extremely important to prevent mold, and this is especially important during the wet winter season.
Be Careful When Storing Items Away for Winter
Many of us store summer clothes, camping equipment, outdoor gear, and other warm-weather items in the basement, garage, shed, or other out-of-the-way area. Make sure any items are completely clean and dry before storing. When possible, store summer gear in plastic tubs (avoid cardboard boxes) and/or on shelving units that sit off the ground. This will ensure they stay dry all winter, even if leaking or flooding occurs.
Get Your Home Tested for Mold & Protect Your Property and Family
Preventing mold from growing in the first place is ideal. Identifying it quickly when it appears so that you can remove mold properly from your home is the next best thing. This will protect your home from damage and protect your family from harm.
If you suspect mold is growing in or around your home, it’s important to have it professionally tested so you know what you’re dealing with and can take steps to remove any mold that has begun to grow in your home. JSE Labs provides safe and accurate same-day mold testing and results.
You can collect your own sample or contact a JSE qualified inspector to come to your home and perform an in-depth visual inspection using moisture meters and particle counters and collect a sample for you. Don’t hesitate to contact us with any questions or for more information.
Lisa started in the industrial hygiene and environmental industry in 1992 as an asbestos microscopist and began performing building inspections for asbestos, lead paint, and other hazards in 1994.
“This career has been an amazing experience, traveling for work to perform inspections both locally and abroad to locations such as Hawaii and Germany. My real love however is being in the laboratory and assisting our wonderful clients.”