When did the building code begin requiring bathroom vent fans to discharge to the exterior (not the attic or crawl space)?

Thursday, April 4, 2019

Although bathroom vent fans have been an acceptable alternative to a window for the required ventilation of a bathroom for many years, the requirement that it be ducted to the exterior did not come along until 2003 or 2006, depending on how you interpret the International Residential Code (IRC) and the corresponding Residential Edition of the Florida Building Code (FBC) for the two code editions. So a vent fan that terminates in the attic, like in the photo below, is no longer acceptable. 


    The 2003 edition of the IRC states at M1506.2 that “exhaust air from bathrooms and toilet rooms shall not be recirculated within a residence or to another dwelling unit.” But, is an attic or crawl space considered to be “within the residence”?

    That question was resolved in the 2006 IRC edition with M1501.2 stating “the air removed from every mechanical exhaust system shall be discharged to the outdoors. Air shall not be exhausted to the attic, soffit, ridge vent, or crawl space.” So, depending on how the local jurisdiction interpreted the code, termination at the exterior was required beginning with the 2003 or 2006 code edition.

    Also, see our blog post 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? 

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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. 

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