Basically, moisture causes mold in homes. However, there are many factors that contribute to mold growth in homes. For mold to grow, there need to be mold spores present in the space. There must be some sort of food source for the mold spores to feed on (this could be anything from drywall to cotton). The space must be warm and moist, have oxygen, and be dark as well. With enough time and these conditions, mold is sure to grow. The number one problem that contributes to mold growth in homes is uncontrolled moisture. This can take many forms, and some of the most common are noted below.
Humidity causes moisture that encourages mold growth in a space. Humidity might come from the climate you live in—like if you live on the coast. It can also come from weather patterns like several days of rain. If your home isn’t well-ventilated, humidity can get trapped in your home and cause the growth of mold. Drying your clothes indoors can also cause humidity problems. Also, excessive use of a humidifier can cause mold.
Whether it’s a pipe under the sink or in a wall, or a hole in the ceiling, leaks can contribute to mold. Leaks that go undetected (like those inside a wall for instance) are the worst because they build up moisture for a long period of time and create ideal conditions for mold growth. Make sure you get your roof and pipes checked regularly to prevent leaks and stop those that have already begun.
Poorly ventilated homes are a mold spore’s paradise. Homes with poor ventilation causes wet spots to dry slower, air to remain stagnant, and moisture to be trapped. Parts of your home that are poorly ventilated are far-and-away the most likely to develop mold. Rooms like the kitchen and bathroom that have running water and encounter a lot of steam should be well-ventilated to discourage the growth of mold.