Bathroom Ventilation

Proper bathroom ventilation is essential because of moisture, common household chemicals, and odors. Moisture invites mold, mildew, bacteria, dust mites, dry rot, and insects into the room. It causes potential allergy problems as well as structural damage. Common household chemicals include cleaning supplies, various solvents and volatile organic compounds and odors. Ventilation is a successful way of getting rid of these unwanted things.


Ventilation Standards For Bathrooms

The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) updates standards for achieving quality environmental air control by determining the minimum residential ventilation rates. For example, bathrooms 100 square feet in area or smaller should use an exhaust fan at one cubic feet per minute (CFM) per square foot, or in other words, eight changes of air an hour. For bathrooms larger than 100 square feet in area, the ventilation rate is determined by the number and type of fixtures within it.

Four things to consider when determining the best ventilation system for a bathroom are:

  • Air movement capacity
  • Noise level
  • Ducting
  • Any accessories desired.

Ways to Properly Ventilate the Bathroom

Typical ventilation systems consist of exhaust fans. This is a form of spot ventilation because it reduces moisture and odor from specific areas or spots. Ventilation systems should flush out stale air while introducing fresh air collected from outdoors. Exhaust points, or forms of ventilation, should be placed over or adjacent to a shower or tub and within an enclosed toilet stall. Bathroom doors should be undercut to allow air to enter and exit the room.

Exhaust Fans In The Bathroom

HVI recommends exhaust fans remain on 20 minutes after bathroom use. Timers with automatic off-switches are helpful, especially with households with young children. Exhaust fans are often combined with a light, heat lights, and/or humidifier-sensors. Sometimes they have an automatic sensor that turns on the fan when it senses an increase of moisture or humidity. These fans typically turn themselves off when the time is right. Previously, exhaust fans were not used properly because of the loud operating sound. Now there are "super quiet" fans that are hardly noticeable.

Windows as Ventilation In The Bathroom

Although exhaust fans are the typical form of ventilation, a window that opens to the outdoors is another option. While windows provide some natural light, they are not as successful in clearing out moisture and odors--they are not as effective as strategically placed as spot ventilation. Considering all the damage that could arise from excess moisture and odors, proper ventilation in bathrooms is crucial to keeping a house and its inhabitants healthy.