Mechanical ventilation of a bathroom with a vent fan has never been a code requirement, but it became an alternative to an openable window shortly after manufacturers started making exhaust fans. Building codes dating all the way back to the 1927 Uniform Building Code have required that “all rooms used to eating, living and/or sleeping purposes shall be provided with ventilation by means of windows with an area of not less than one-eighth (1/8) of the total floor area of any room or rooms."

    A specific ventilation requirement for bathrooms began in the 1946 Uniform Building Code, with the citation shown below, courtesy of Jerry Peck.

    So an unventilated bathroom, without either a window or vent fan, has never been acceptable per the building codes. Also, see our blog posts When did the building code begin requiring bathroom vent fans to discharge to the exterior (not the attic or crawl space)?  and Does a half bathroom (no shower or tub) require an exhaust fan?

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  To learn more about heating and air conditioning systems, see these other blog posts:

• How can I find out the SEER of my air conditioner? 

• My air conditioner won't turn on. What's wrong? 

• How can I find out the size of my air conditioner? 

• How can I find out the age of my air conditioner or furnace?

• How can I tell whether the condenser (outdoor unit) is an air conditioner or heat pump? 

• Where is the air filter for my central air conditioner and furnace? I can’t find it? 

• Does an old air conditioner use more electricity as it ages? 

• How did homes stay cool in Florida before air conditioning?

• What is wrong with an air conditioner when the air flow out of the vents is low?

• Why has the thermostat screen gone blank? 

• Why does it take so long to cool a house when an air conditioner has been off for a while? 

• Why is my air conditioner not cooling enough? 

• What are the most common problems with wall/window air conditioners?  

• Will closing doors reduce my heating and cooling costs? 

   Visit our HEATING AND AIR CONDITIONING page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.