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Bathroom Exhaust Fan

by / Wednesday, 17 June 2015 / Published in Healthy Building Inspections & Testing
Bathroom Exhaust Fan

How Effective is Your Bathroom Exhaust Fan?

For obvious reasons, bathrooms can be major sources of moisture in homes. And where there is moisture, there is the possibility of growing mold. A bathroom exhaust fan is essential in removing excess moisture and keeping bathrooms ventilated, but how do we know if our exhaust fans are working properly? Just because we can hear them doesn’t necessarily mean that they are effective.

Ventilation is key to reduce mold in the bathroom

A simple way to test your fan’s suction is to take a single square of toilet paper and place it along the fan vent while the fan is running. If the fan holds up the toilet paper, then the fan is working properly. Keeping the bathroom door open while running the fan will allow for air exchange from other parts of the home. It is also important to make sure that the exhaust fan is vented outdoors.

We recommend using bathroom exhaust fans for 15 minutes after using the shower to help move humid air out of the living space. 15 minutes may be longer or shorter than required to keep your bathroom dry, depending on the bathroom size, building materials, windows, etc. It may also be a good idea to install a timer switch in bathrooms which will automatically shut off the exhaust fan after a preset amount of time.

Dry, well-ventilated bathrooms are important in preventing mold growth in bathrooms.

Controlling moisture with the help of an adequate exhaust fan is key. The following links provide more information on bathroom exhaust fans, and on general mold and moisture issues:


Healthy Building Science is an environmental consulting firm providing mold testing and mold inspection services for commercial, residential, multi-family, buildings, offices, industrial and manufacturing workplaces, hospitals and medical facilities, and single-family homes in the greater San Francisco Bay Area and all of Northern California


4 Responses to “Bathroom Exhaust Fan”

  1. Alex says :

    In our routine quarterly home inspections we service bathroom exhaust fans at least once a year. Typically that involves removing the faceplate, dropping down the fan itself, cleaning the blades and accessible components, oiling the moving parts, and replacing the fan. It takes time, but it lengthens the life of the fan and often results in more quiet operation. If you’re in the San Francisco Bay Area and interested in home maintenance – check out Home Stewards.

  2. […] l’occasione per testare e migliorare la ventilazione nel tuo bagno. Molte vecchie case avere una ventilazione insufficienteche contribuisce alla crescita di muffe e […]

  3. Tex Hooper says :

    You make a great point about making sure you use the exhaust fan after using the shower. I think my fan is broken. I’ll have to consider ordering a new one online.

  4. […] How effective is your bathroom exhaust fan? – Healthy … […]

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