Though bathroom fans may seem like somewhat incidental equipment, they are very important for controlling high humidity in bathrooms. In most regions, building codes require bathrooms in new homes or remodels have ventilation fans.

When humidity builds up in a bathroom that doesn’t have proper ventilation, warm moisture-laden air moves toward cooler surfaces, such as the walls, where it condenses back into water. Depending upon where it condenses, it can peel the wallpaper or paint off the surfaces and encourage the growth of mildew and mold. Or–worse–the moist air can condense inside the walls, where it can cause dry rot and serious structural damage. A bathroom fan collects the bathroom’s moist air and expels it outdoors, often through ductwork in the walls or ceiling.