Bathroom venting

I seem to recall an old code that allowed bathrooms to be vented with an X number of air changes from the HVAC system. Can someone educate me? I know what new code requires.

The Home Ventilation Institute recommends a fan capable of 8/ach for a bathroom. I don’t remember seeing a figure for a general forced air HVAC system. Does anyone have a copy of ASHRAE 62…I can’t find mine at the present and have to run out.

I am reaching back into the 70’s or 80’s. I could almost bet a steak there was an allowance for HVAC air exchange in lieu of a window or exterior fan. Perhaps it was a local thing or I got hit by lightning.

Saying that there are air changes involved with the HVAC system means that there would have to be a return in the bathroom. This should not be allowed.


The oldest code referance i have is 1984. it only allowed for operable window or exhaust fan

Thanks all. I may be dealing with a local exception from the long distant past. Some homes in Dallas have a 1/2 bathroom in a hall (toilet sink only). They have no exhaust vent, no recirculating vent, no window, no HVAC return and only a HVAC supply. It is common from the 70’s period.

So to vent the bathroom you push all the humidity into the home?
Something smells here:)

That is the difficulty of code. In North Texas the lack of ventilation in a bathroom rarely causes a moisture problem in the home or attic. This would be especially true in a 1/2 bath that is used incidentally. It is proven by performance history on homes that are 40 years old.

I would do it different in your climate.

Odors? A window and fan would do no good for some. It gives the movie title “The Last Airbender” meaning.

Write it up? Sure. Is it material? Not in Texas.

I guess if you have no humidity in your climate the bathroom air would be helpful.

There is not going to be much humidity from a half bath