I would like to add, that you need to check to see if Air Admittance Valves are code-compliant in your area.
Also, you would need a heftier AAV than the Studor
"mini" vent to add to the system with three fixtures.
Something like a Shur-Vent II from Oatey is up to the job.
The plumber can you advise you.
: : e-plumber: thanks for swift reply... I did inspect the basement ceiling myself and could not find anything. The only pipes coming down are the main waste stack (4 in) which also has a pair of 2 inch pipes that I assume are the drains for a bar sink and mudroom sink. I am beginning to think 1st floor walls may have to be torn down...
: : Is it typical for rough in installs to include a mating vent pipe from the 1st or 2nd floor above? Wondering if I have any leverage with the builder here. Seems foolish to me anyway, to rough in everything in the basement but yet not leave anyway for the vent to get attached to the 1st or 2nd floor vents.... Am I wrong here...
: You're 100% correct, it would make sense to have a future vent connection already in place. Hopefully walls/ceilings will not need to be opened to locate an existing vent line. Is it possible that one of the two 2" lines that you can see is a vent, or can you see that it connects directly to the 4" stack? Another option would be that they planned on using air admittance valves to vent the basement plumbing fixtures, which IMO is always a last resort for venting.
: : : Reply:
: : : There could be a vent in the ceiling of the future basement bathroom. Contact the builder and find out exactly what was provided. A licensed plumber will be able to inspect and see what could be done also.
: : : Good Luck. e-plumber