How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
site-built, mobile/manfuactured and modular homes
What are the exhaust fan requirements for a mobile home bathroom?
Thursday, February 20, 2020
Every time a bathroom is used, it generates humidity and odors that need to be exhausted outside to maintain a healthy indoor environment. HUD did not require mechanical ventilation of baths until the 1994 update of the HUD-code, but most manufacturers were already installing exhaust fans because of customer demand.
The bathroom fan is required to move 50 cfm (cubic feet of air per minute). Ordinarily, the bathroom light and exhaust fans are on separate switches but, if there is an ongoing moisture problem in a bathroom, you have a choice of three ways to get more air exhausted from the bathroom:
- Tie the circuit for the exhaust fan to the same switch as the lighting for the bathroom. This is the cheapest solution and guarantees that when the bathroom is being used the fan is on, but will not keep the fan operating as long as the next two solutions.
- Replace the on/off switch for the bathroom exhaust fan with a timer switch, like the one shown below. You can adjust it to continue running for several minutes after you leave the room.
- The newest technology is a fan control switch that incorporates a humidistat device that doesn’t turn the fan off until the humidity and temperature in the room have reached an acceptable level. A photo of one made by Panasonic® is below and, depending on the brand, this hi-tech solution will set you back $40 to $60.
Bathroom fans must also have a backdraft damper, which is a hinged flap that closes when the fan is off to prevent air leakage, and relies on gravity to shut.
Also, see our blog post How energy efficient is a mobile home?
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