Adding washtub sink to a workshop in basement

[MorseCodeScott]

I'm hoping the answer to this question is as simple as it appears, but I'm afraid it might not be.

I have a small room that I would like to add a washtub sink to. This room is on the back side of a bathroom, so I have an exposed wall with access to hot/cold water pipes which I can tie into and that appears to be pretty straight forward. I also see a drain or vent that I'd like to tie the sink drain into.

My concern is that I think this is a vent pipe though, so I'm not sure if I'd be messing something up by trying to tie into this. A few bits of information, this is in the basement so there is nothing below it, and the pipe goes right into the foundation. It travels up through the ceiling into a wall on the main floor, then I assume continues up to the second floor, but I can't trace it past there. I've turned on the sinks upstairs and went down to listen and see if there is any water draining in the pipe and i can't hear anything in it, so assume they all run into another pipe in a wall somewhere and that's what leads me to believe this is a vent.

So my question: Can I install a T just above the floor and run the sink drain into this? (I'm in New Brunswick, Canada in case that's relevant)

I've included a couple pictures to try to give a better visual. one is my crude attempt at a floorplan

 

[Cwhyu2]

That is the vent for your shower drain and no you can not just cut a tee in.

 

[Sponsor]

 

[hj]

That is the shower vent, and YES, you can connect the sink to it and thus wet vent the shower, but you could NOT use the drain for something line a clothes washer.

 

[Cwhyu2]

According to IPC you can only wet vent a bathroom group and not an individual fixture.

 

[hj]

Now, that would be a stupid statement, if it is factual, (but that applies to many features of the IPC). Many "bathroom groups" are spread out so ONE wet vent would not always work that way. AND, if you can wet vent MANY fixtures with one wet vent, it is obviously better if only one is on the wet vent.

 

[Cwhyu2]

If you cut in a tee on that vent and you drain the sink it could siphon the the trap of the shower stall, you would have to revent the shower stall.

 

[MorseCodeScott]

Ok, well that's what I was afraid of. So it's definitely a vent. It looks like there are mixed opinions on using it as a drain and thus creating a wet vented shower.

The possibility of siphoning the trap of the shower stall sounds like it wouldn't be a good thing. Just a matter of note, neither of these fixtures would be used very often. The shower is in a guest room that would not be used 99.9% of the time and I can't really envision a scenario where they would both be used at the same time.

The other option that I have to is to open the drywall on the opposite side and try to tie in to the drain for the bathroom sink? Would there be any issue with doing that? It's a lot more work and involves cutting holes in walls but if that is the only way then I'll have to do it.

I guess there is a third option as well that I really don't want to explore but it would be to cut a hole in the foundation floor and try to find the drain from the shower and tie in further down the drain so I wouldn't affect the vent.

 

[hj]

quote; If you cut in a tee on that vent and you drain the sink it could siphon the the trap of the shower stal

And HOW is that any different than ANY wet vent?

 

[MorseCodeScott]

So, is there anything that can be done to avoid the siphoning aside from not using the vent? And what is the worst case scenario of siphoning the trap of the shower? bad smells, sewer gases, etc?

 

[Terry]

So, is there anything that can be done to avoid the siphoning aside from not using the vent? And what is the worst case scenario of siphoning the trap of the shower? bad smells, sewer gases, etc?

Horrible smells.

 

[Cacher_Chick]

So, is there anything that can be done to avoid the siphoning aside from not using the vent? And what is the worst case scenario of siphoning the trap of the shower? bad smells, sewer gases, etc?

Cut the floor to access the drain downstream of the other fixture's vent.