Venting 1 2 bath on 1st floor i don t know what code you guys go by or where you can put an aav below the flood level rim of any sink but it sure won t fly with nspc in nj injustice anywhere is a threat to justice everywhere mlk.
Dry venting 1 bathroom first floor 2 bathrooms second floor.
Irc section m1501 1 outdoor discharge.
Second you must vent directly to the outside whether you vent through the attic or wall to meet today 39 s code requirements.
It would appear to be easier to install a wall or floor fan and direct exhaust down and then out through basement wall just above ground.
How to vent a 1st floor bath.
First this is very do able.
But while you can t have two fans with one vent you can make one fan and one vent serve two bathrooms.
In single story homes the duct.
The vent that services a fixture must have a diameter at least half as large as the drain pipe but the minimum pipe diameter allowable is 1 1 4 inches.
You d often blow air from one bathroom into the other and local building inspectors wouldn t approve it.
Setting the plumbing for a new bathroom requires you to connect supply water pipes and drainpipes to existing systems.
Bathroom fans also called exhaust fans prevent moisture damage and mold by forcing air through a duct to the outside of a building.
If the new bathroom is on the second floor the bathroom s main drain will have to travel through the wall on the first floor and down to the basement or crawlspace.
My bathroom is on the first floor with a finished bedroom directly above and an unfinished basement directly below.
I have read that moist air naturally rises so it is easier to vent up.
This setup requires an in line centrifugal fan mounted in the attic drawing air simultaneously from both bathrooms see photo.
Adding a bathroom to the second floor of your house.
The air removed by every mechanical exhaust system shall be discharged to the outdoors.
If a drain line is nearby you may choose to run a pipe to it rather than running a new line.