Bathroom Humidity Issues

By Robert Robillard on Bathrooms

Importance Of Bathroom Ventilation

Bathroom fans are a necessity in today’s air tight and energy efficient homes and help mitigate bathroom humidity issues. Ventilating the pollutants from cooking and showering is vital to the health of the residents and to the structural integrity of the home.

Bathroom Humidity Issues

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.

Moisture vapor can peel wallpaper or paint off the surfaces and encourage the growth of mildew and mold. Moist air can condense inside the wall cavity, where it can cause rot, mold and serious structural damage to wall studs, sheathing, and ceiling and floor joists above and around the bathroom.

Bathroom Mold

Mold in the bathroom is especially problematic and has become a huge concern for today’s builders. Mold is a fungus that thrives in warm, dark, humid environments. It spreads via spores that grow on wet or moist surfaces such as wood, wallboard, and bathroom tile.

The only effective way to prevent mold is to attempt to keep indoor moisture levels low. Mildew is simply a type of mold that spreads particularly well in organic, moisture-rich environments.

A bathroom fan collects the bathroom’s moist air and immediately expels it outdoors, through duct work in the walls or ceiling. Most times people use the fan during the shower but immediately turn it off after they are done showering which does not resolve bathroom humidity issues.

Best Practice For Bathroom Humidity Issues

Ventilate and control all fans with timer switches.  I feel that the best all-around and most cost-effective way to remove humid air from showering is to replace your light / fan switch with an automatic timer switch. The fan goes on when you set the timer, then shuts off when the time runs out.

bathroom fan timer switch
Image: RD.com

Using a timer switch allows you to remove humidity for up to 30 minutes after you leave the room, without the worry of forgetting to turn the fan off.

Don’t have a bathroom fan?  Get one installed and read Bathroom Duct Venting Options,” and “Installing A Bathroom Vent Duct.”

Ventilation Rule Of Thumb

A good rule of thumb, according to the Home Ventilating Institute, is to run your fan for 20 minutes following bathroom shower use.  The use of the an and timer switch will work as a team to eliminate bathroom humidity issues.

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About the author

Robert Robillard

Carpenter / Remodeler / Editor

Rob Robillard is “The Concord Carpenter” Rob is a builder, general contractor, carpenter, woodworker, and editor of Concord Carpenter and ToolBoxBuzz As a General Contractor and carpenter, Rob owns and operates Concord Carpenter LLC. A full-service remodeling and construction company. Rob is a recognized leader in home building best practices and a source for how-to information for building professionals. On this website, Rob covers all aspects of home construction, building science, home improvement, woodworking, remodeling, and some of the best product and tool reviews. Rob is in charge of our Tool and Product Review series - Concord Carpenter Videos where we post all of our tool reviews and video tutorials. Rob approaches remodeling and building construction with a pragmatic and problem-solving approach. He enjoys using his knowledge and experience to help and educate building professionals as well as DIYers on best practices in the construction and remodeling industry. He's a strong advocate for "raising the bar" in the construction trades and promoting the trades to youth. #BeAMentor #Green2Great Craftsmanship, quality, and pride guide his journey on this channel The Concord Carpenter's motto: "Well done is better than well said!" : Read more about Rob

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