I have a washroom in basement which at times I seem to have a slight sewer gas smell. I am in process of building the washroom now. The rough in was done by previous owners, but there is what appears to be a vent stack that comes up our of the floor just left of the main drain rises about 8 inches and then lowers toward the main drain and vent stack.

This seems very strange as the pipe closest the washroom is higher then the drain, which I think would cause the gases to sit in the higher end and build up.. I was planning on removing it and connecting it directly into what appears to be the vent stack at a 45 angle.

Is this a wrong way to do it or could it be done at a 90 angle to the stack. And could this also be the source of the smell. The drains all seem to work fine, I have ran a garden hose into all the drains and they all drain perfect. I notice the smell the most from the shower drain which is the farthest away.

Gotya... you are right... something wrong here. Vent is too low... you can connect with a 45 or a 90just make sure you connect into vertical pipe six inches higher than the finished height of the lavatory sink top in the basement.

Where are the other vents for the bathroom?? And where/how do they connect into the vent system?

Sewer odor... Hard to say.. tell us more about the rough in... could just be a loose test cap if roughed in pipes. Maybe a pic of entire bath rough would help. Get back to us.

The rough in is as follows. The shower is the farthest away about 7-8 feet away from that vent stack, the sink follows about 3 feet from that and finally the toilet which is about 4 feet from sink. The vent pipe in picture is about 2 feet from toilet drain.

As for vent pipes the one in the picture is the only one for the house. It is a bungalow and upstairs are 2 washrooms and kitchen all within a 5 foot radius of the plumbing in picture.

the basement rough in is all 2" pipe until it gets to the strange low vent pipe where it converts to a 1.5" pipe to tie in with the other vent/drain. I was planning on cutting the 2" on the left and raising it about 5 ft up and then tie in directly with the vent pipe on the right. After reading the site I found out about the 6" above th highest dain usually the sink which I was unaware of and will follow, I was also reading on the critical distance which what I could find on web is 48 x drain diameter (2") which would give me 96" and for the shower falls within this limit, I hope I understood that correctly.

For the sink in basement it will be inside the wall I could run a new vent pip off off the drain and tie that also into the same vent stack. But is there a limit to the number of drains that can be tied into a single vent stack, or is it based on distance.

Thanks in advance

Here is the picture of the full rough in. The shower drain is on the left with the concrete dug up around it as it was partially broken and I needed to move it a few inches over if possible.

The sink drain is in the middle and right up against the wall, which will end up behind the wall once the insulation is in and covered. The toilet and then the left side of the vent in the original pic.

OK... here is my take on it. Looks like that 2" pipe you presented in first photo is a toilet vent. I would run my lavatory vent (full size 2" as I believe that the lavatory vent is a wet vent for the shower) up the wall and into and down the joist bay to join into the toilet vent up in the joist bay together... then run that full size 2" into the upstairs bathroom (if 2" vent present there) and connect into vent there or run vent up into the attic and connect at a vent there OR penetrate roof with new roof boot full size 2" for about 24" past roof line.

See... unless that 1.5 inch pipe you presented in first photo jumps up to 2" somewhere I can't see in basement...it is too small to vent this bathroom.

Again, tie pipes together at joist height and run up...OR drill series of holes through studs at 48" off floor (pitching back toward lavatory) to the toilet vent area and connect toilet vent and lavatory vent about 50 inches of floor.. then run that pipe vertical as presented.

That should so it for you.

Hey... copper is looking good... what are your rough heights for toilet and lavatory and shower? They look a little high... especially the lavatory. Let me know (the square in pic suggests you are a little high... just confirm numbers for me). Thanks

Thanks it is my first real plumbing attempt. The lines are about 21" above the concrete. I only hope there are no leaks when I finally tie it into the main line. Still need to finish off the shower as I am adding a couple of shower jets and rain shower but still reading on some of the requirements. Shower will be 4x5. I will run a 2" pipe up along the wall. The wall is actually 2x4 with a 2" space at back so I could but in R22 insulation on top of the R2.5 rigid against the wall now. I am finding this forum very helpful and also learning new terminology, I don't have much information on plumbing more electrical neither of which is even close to my profession, but learning as I go. I will hopefully have something dry fit this weekend and will post a pic.

Thanks once again for you help it has been very useful.