I have an up and down condo where I own the second floor and do not have access to the first floor to make changes.. The master baths are stacked and use a common 3" vent stack. I want to make my master bath slightly larger and move the WC back toward the vent stack about 12". This puts it right on top of the shared stack. Can I mount my WC directly on the 3" stack assuming I continue the vent by coming off the existing 3" stack under the WC?

I have an up and down condo where I own the second floor and do not have access to the first floor to make changes.. If you haven't access to the first floor so you can open up the ceiling to make the changes how do you intend to proceed? Let me know. Tom

Do you belong to a Condo Associiation, is there a covenant agreement covering your units?

If you haven't access to the first floor so you can open up the ceiling to make the changes how do you intend to proceed? Let me know. Tom

It is a wood frame building I will pull up the floor in my bath to access the pipes. I have already investigated pipe layout via video. Current WC is connected to the stack via 3x3 sanitary T I assume I could remove the T put in a 3x2 Y on top of the stack and take the 2" VTR the WC flange on top of the Y.

I have done many such a toilet relocating - but never where toilet would fit exactly on top of the stack. There was always some way to Tee it off from the stack.

I don't see any problem doing it the way you want to do it provided it is roughed-in just like you explained and as long as you don't eliminate the existing vent and -of course - reconnect it. However, let's see what other Experts have to say...

On personal note: Be careful with doing such a major toilet relocating and pipe modification in a condominium building. You don't own what's inside the walls. If there is any problem with leaks or back ups, you may put yourself in a quite uncomfortable situation. I would talk to the HomeOwner's Association first and also have it inspected by City Inspector - just to be on safe side.

Good luck and let us know how it all worked out for you. Milo

I agree and had the same suspicion in post #3. Many condos are set up where you own from the paint on in but nothing uder the paint. Much of the structure is considered common property and it is not yours to modify

In my experience the only problem with bringing the vent from the drain instead of the drain going to the vent (for toilets) is that you sometimes will end up with a gurgling sound on the toilet flush which of course means it wants more air.

in my experience the only problem with bringing the vent from the drain instead of the drain going to the vent (for toilets) is that you sometimes will end up with a gurgling sound on the toilet flush which of course means it wants more air.

Thanks for your responses.

I reread this question and realized I was in a hurry yesterday and left and important part out of my response. I have only noticed that gurgling when you take the vent off a vertical toilet drain directly below the collar. Which is what I believe you intend to do.

That vent could be considered "common area" and most Condo Docs. Don't allow you to modify a common area. Check with your Condo Board for approval. Good luck, Tom