Why Does My Home Smell Musty in the Winter?

Winters can be quite cold and long in Toronto and during those chilly days, windows in many homes are usually shut most of the time. While this is an excellent way to keep indoor temperature in a pleasant range when the cold bites to the bone, this practice also significantly increases air humidity. Showering, using home appliances like washing machines and dishwashers, drying clothes inside and other common home activities create a significant output of water, which later eva reporates due to warm temperatures, increasing air humidity. If the windows are closed and there is no ventilation, a lot of that water vapour will eventually end up in furniture and walls, creating a wet, musty smell in the house.  If the smell is only a result of increased humidity, it should disappear after some venting. However, if the musty smell remains, or even worse – gets stronger even with proper venting, it is a big indicator that mold and/or mildew is present. These fungi thrive in moist environments and can spread very quickly, which makes them a serious threat to indoor air quality.

Causes of Musty Smells in The Home

There are a variety of things that can cause increased humidity in homes, and consequently provide a cozy environment for main culprits of musty smells to develop: mold and mildew. The smell is usually lighter in the beginning, which gives at least some time for finding and removing sources of excess moisture before the situation gets out of hand. Here are some of the most common sources of moisture and musty smells in Toronto homes, especially during the cold part of the year: home smell musty - odor removal

Leaky pipes & clogged drains

Leaky pipes and runny faucets are the most common sources of excess humidity in homes, making them one of the primary mold catalysts. Musty smells can also come from bathroom and kitchen drains – sewer gases may rise as a result of changes in air pressure (for example, when it rains), releasing nasty odours. Improper drainage and accumulated water can also cause foul smells around drains, as well as increased humidity which leads to mold and mildew development.

Wet coats, clothes and footwear

Given the cold and wet Toronto winters, laundry cannot be hung outside to dry. When dried inside, wet clothes release significant amounts of moisture into the surrounding air. In addition to clean clothes, wet coats and boots soaked by precipitation are also common sources of moisture, as they need to dry after every trip outside if it’s snowy or rainy. Accumulation of all this evaporated water often leads to musty smells and mold development.


Pets can also cause musty smells in home by bringing in water from the outside. Their paws trek groundwater into the home, and their fur can soak up significant amounts of water, so they need to dry after every outside venture – which happens quite often, especially when dogs are in question.


The difference between outside and inside temperature that often occurs during the winter can generate a lot of water condensation around windows, providing favorable conditions for mold growth. The problem can be significantly increased if the window also isn’t set properly or if some elements are worn out, as leaks will allow snow and rain to get in.

Spores and air pollutants in HVAC system

Humid, moldy smells coming from a HVAC system can be very alarming, as these systems have very favorable conditions for mold development – they are hidden from light, are warm and humid, and they also collect a lot of dirt and dust which serve as good source of food for mold. Mold thrive in such environments, and they can develop very quickly, releasing millions of spores which then contaminate indoor air and spread the infestation. It is very important to keep the vents as clean as possible and to change filters at the proper time to prevent dirt and dust from accumulating.

How to Fix the Problem Once it Occurs?

It can get very hard to keep the moisture levels low in the home during winter, as there are so many sources of water both outside and inside. This, coupled with poor air circulation and great differences in temperatures inside and outside the house, significantly contribute to the occurrence of musty smells during winter months, and provide favorable environment for mold and mildew growth. These conditions negatively affect air quality in the house and may become a serious health hazard if left unchecked.

If there are any doubts of mold presence, it is advised to resolve the problem as soon as possible because molds multiply and spread very quickly. The best way to deal with mold infestation is to call a trusted mold testing and removal company. Professionals from Inch by Inch Inspections provide high-quality mold and odour removing service in Toronto and the GTA. Experienced staff of Inch by Inch uses the safest and most efficient removal methods to ensure that the air in your home is clean and healthy again. Call to schedule your inspection today.

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