Moisture problems in bathrooms

We get asked to look at moldy bathroom tile and failing tub surrounds quite often. While we can make the tile waterproof and make it function like it should, what we find is that most people seldom use the fan that is in their bathroom. Or if they do use it, it is only used for the another purpose. To the point that HVAC installers have started calling bathroom exhaust fans a “fart fan”.

Yes, these fans do remove smells and odours. But the main purpose for these fans being installed in bathrooms is to remove the warm moist air that is in bathrooms while they are being used. Whether it is from having a bath or shower, or just brushing your teeth. That humid air needs to be removed to stop mold and mildew from developing and causing damage to your home or business. It is important to note that this air needs to be removed from the building, not just the room. Often times when we are completing bathroom renovations we find exhaust fans that are vented into attics or even down and into other wall cavities. This can cause a lot of damage in your home, by allowing moisture to build-up in areas where it shouldn’t.

Often times we see homeowners not using the fans properly because they are either loud or are not installed correctly.  Both of these problems can be easily fixed:

Sound: By installing a fan that is under 1.5 sones a fan is much more likely to be used.

Installation: A bathroom fan should be ran for 20 minutes after a bath or shower has been had in the room.  This means that a fan should never be installed on the same switch as a the light above a shower for instance because most people will shut the light off when they leave the room. We recommend using a timed switch that allows for 15 minutes of operation after you leave the room. That way you can set the timer and forget about it. Along with the timer, running the ducting properly so that the air is removed from the building is important. As well as making sure this ducting  is insulated to protect from condensation in unconditioned spaces.

Your bathroom exhaust fan is an important part of keeping moisture managed in your home to prevent mold.  Along with the waterproofing around your shower and on your bathroom floor you also need to control the moisture that is in the air.  With a high quality bathroom fan and proper installation you can ensure your bathroom and its finishing last a long time.

Check out this article from CMHC for more information on preventing moisture problems in bathrooms: https://www.cmhc-schl.gc.ca/en/co/grho/moaiprre/moaiprre_009.cfm