How High Humidity Breeds Mould

As we’ve discussed in previous blogs, mould quickly starts growing with the introduction of moisture. When you think of this moisture, you probably think about water in your bathroom or water damage from your washer or refrigerator. Yes, this can be the moisture that starts mould growth in your home, but it isn’t the only catalyst.


Mould can grow rather quickly, but you may not realize the role that humidity plays in this. High humidity (water vapour in the air) can be enough moisture to start mould growth as well as provide the perfect environment for it to continue to rapidly grow. Obviously, this is a bad thing.


If you fear that you may have mould already growing in your home, finding a way to control the humidity is one clear way to slow down growth. Ideally, the sweet spot to do this is between 30% - 50% for indoor relative humidity (RH). If you’re unsure of how to control your home’s humidity, let’s take a look at some of the reasons why your humidity might be higher than this ideal range.


    • Your location. Some areas of the country are more susceptible to high humidity levels. If you live in one of the most humid areas of the country, you are at an immediate disadvantage when it comes to your humidity levels.


  • Poor ventilation. If your home is not properly ventilated, the quality of your air is greatly diminished, with fresh air from outside not able to be ventilated inside. With fresh air not coming in and your current humid air unable to escape, you maintain levels that will lead to further mould growth.
  • You experience high rainfall. If you’ve experienced high rainfall in your region due to location or time of year, you are going to experience high humidity levels.
  • When you shower or cook. When you perform everyday tasks in your home like showering or cooking, you will add condensation to the room. If you don’t have a cooking hood or a bathroom vent to allow proper ventilation, the humidity will only get worse.
  • You use gas or propane heaters. When cold weather hits, you want to stay toasty warm. The use of gas or propane heaters can, however, add condensation to the air and increase the humidity levels within your home. Ensure you have proper ventilation to minimize the levels of water vapour that stays inside.



Based on these humidity sources, take steps to improve your home’s ventilation to improve humidity levels. You can also use a dehumidifier to remove moisture in areas like a basement or bathroom. By controlling your home’s humidity levels, you can help contain the potential growth of mould.


If you have mould present in your home, call the mould damage restoration experts at Paul Davis at 1-800-661-5975. Call Paul!