[dclynch]

I discovered an unvented lavatory during a bathroom renovation and would like some advice on what to do.

The house is 110 years old and had a small bathroom installed on the top floor in the mid-60s. We've been using the bathroom for the 25 years we've lived in the house without any plumbing problems, but decided to re-tile and replace old sheetrock, etc. When the wall came down, it turned out the lavatory has no vent, just a 90 degree bend on a 1.5" drain pipe that then passes under the floor for about 5' and then enters the main drain. Since we just intended to do the walls, the project did not need a permit/inspection.

Ideally, I'd like to run a 1.5" vent into the attic and connect to the existing vent system, however, I don't see a feasible way to do this. We want to preserve the existing fixtures and medicine chest for aesthetic purposes. They are green and cannot be matched today. Don't try to imaging why we want them :-)

The problem is the stud space is only 2" deep and the straight up direction is obstructed by blocking for the wall mount lav and by the recessed medicine chest. If I bypass the blocking by putting a pair of 90 degree turns on the vent, the neighboring stud (that supports the lav blocking) would be almost completely destroyed.

It seems my choices are:
1) Leave it alone and close up the wall.
2) Make the 90 degree turns, but use 0.5" PVC for that portion of the vent.
3) Use a Studor-type vent, but these are not permitted in my area and would be obvious in any future inspection.

What do you think is best? Is there another alternative? What would an inspector require?

Thanks for your help.

[speedball1]

The problem is the stud space is only 2" deep and the straight up direction is obstructed by blocking for the wall mount lav and by the recessed medicine chest. If I bypass the blocking by putting a pair of 90 degree turns on the vent, the neighboring stud (that supports the lav blocking) would be almost completely destroyed.

It seems my choices are:
1) Leave it alone and close up the wall.
2) Make the 90 degree turns, but use 0.5" PVC for that portion of the vent.
3) Use a Studor-type vent, but these are not permitted in my area and would be obvious in any future inspection.

What do you think is best? Is there another alternative? What would an inspector require?

Tough situation! As A rule I'd recommend installing a AAV,(see image) on that "S" trap bgut you must be under UPC.
Number two isn't acceptable either. So where does that leave us?
Back in Wisconsin in the 40's I saw many older homes without venting and they worked just fine. I don't recommend leaving any fixture unvented but if it's worked for years without a vent I say, "cover up the wall".
I realize that there will be some experts that disagree with me but this page isn't about bringing every house in the nation up to code. It's about getting the homeowner repaired the easiest, the fastest and the least expensive.
Good ;luck, Tom

[massplumber2008]

As usual, I'm going to vote the same way as Tom on this one, for sure!

"If it aint broke...don't fix it"!

Good luck!

MARK