How do I vent this basement bathroom?

[tippsand]

Hi -

How do I vent this bathroom that was roughed in before the house was completed?

Same bathroom in all pix, just showing what the room looks like now (we had to cover the studs since the inspector decided the basement was "finished" and he wanted it fire rated).

2" from lav and tub; the tub ties into the lav line, which wyes into the 3" downstream of the toilet
3" main stack from upstairs (now enclosed in the wall, and servicing the rest of the house)
4" toilet

3 plumbers gave 3 different bids with different thoughts on what "had" to happen:

#1 said add studor vent to lav in a vanity; will vent the whole bath group = $
#2 said extend the vanity 2" line up the wall and tie in to a vent on the first floor (open drywall in the bathroom directly above) = $$$
#3 said jackhammer the slab around the toilet and tub drain; cut a tee in and run a 2" vent up the wall between the tub and toilet and tie into something in the 1st floor joist space (couldn't tell what he was planning on tying into...) = $$$$$




What's the best, easiest way to do this? I'm not afraid of the work, and will do it myself if there's a better way. I'm just concerned that there are three different "right" ways so far.

 

[Terry]

If the lav line is run in 2", the tub wyes in after the lav and before the toilet, then an AAV at the lav will vent the bathroom.
I think the first guy has it right. $

 

[Sponsor]

 

[tippsand]

That was EXACTLY what I was hoping.
Followup question - plumber #3 said that an AAV at the lav would make this sink gurgle and bubble whenever there was any activity on the downstream 3" main stack and that over time, the trap in the sink could dry out. Was he just trying to be cautious or trying to scare me into thinking his way was the right way?

Thanks!

 

[hj]

That CAN be one result of using an AAV in a lower level bath system. #2 was the "right" way, but I am curious as to why, if the bathroom was installed during construction why a vent was not connected, or at least provided.

 

[tippsand]

That CAN be one result of using an AAV in a lower level bath system. #2 was the "right" way, but I am curious as to why, if the bathroom was installed during construction why a vent was not connected, or at least provided.

Hi there-

Thanks for your response and I'm glad you asked about a vent being provided.

Armed with my new knowledge about AAV (thanks!), I decided the bathroom vent problem was solved, and my next problem was putting in an exhaust fan for the bathroom, since it's below grade and already has some humidity issues. So I cut a hole in the ceiling and saw a capped 1.5" pipe directly above the vanity in the first floor joist space, extending down from somewhere above. It's capped and I don't know where it goes. See the new pic (in the pic, the 3" pipe is a lateral that drops to the 3" pipe in the first pictures).

So now I wonder -
a- Could this 1.5" capped pipe be a vent that was provided for the basement bath OR
b- On the first floor of the house, directly above this bathroom is another bathroom AND a mudroom (they share a common wall). In the mudroom closet, we prepped for a stacked washer / dryer, so there's an Oatey in-wall box with H/C supplies and drain hole (currently covered with a twist-lock cap). When you go back down to our basement bathroom, the 1.5" capped pipe in the joist space seems to be underneath the prepped-for laundry. So maybe it's a drain for the washer instead of a vent?

I guess one way to check would be to dump water into the laundry box in the mudroom and see if it drains or backs up. If it backs up, it's hitting the capped 1.5" (which is a whole new problem...)

If it drains from the laundry box, then can the 1.5" safely be assumed to be a future vent for the basement bath??

Thanks!

 

[FullySprinklered]

Almost certainly your vent.

Take care should you decide to use it. They often are full of rainwater. I needed two five gallon buckets last time I drilled one. The pressure may surprise you.