I have a little privacy wall off to the side of the toilet in a 1/2 bath. We want to take the privacy wall out, and wouldn't you know it, that is where the toilet vent pipe is. Best I can tell (haven't stripped down the privacy wall yet), the pipe runs down into the foundation and connects up with the toilet drain under the foundation.

I'm wondering if I can cut this pipe just above the floor, then put a 90 degree elbow in the pipe to re-route it into the wall that's behind the toilet, and then either put it up through a different hole in the roof, or re-route it back to it's current position once it gets above the ceiling... or, does the pipe need to be straight all the way out the roof?

The pipe does not have to be straight but if you cut at the floor and add a 90 you'll be about 5-6 inches above the floor. Is this what you really want? Can you see where the vent stack and the toilet drain connect?

Thanks for your quick response!

No, that's not what I really want either, but I'm looking for all the possibilities to present to the boss!

I took off some more sheetrock, and this pipe goes directly into the foundation. It is about one foot to the left of the toilet as you stand facing the toilet. It must connect under or in the foundation, so I cannot see where the vent stack and the toilet connect.

You cannot have the vent running horizontally until you are at least six inches above the flood rim of the fixture being vented.

Is there another bath above this room? This might be a drain. Your floor cavity should be about 8" you could cut above the lower ceiling and you existing floor.

So, what is the 'flood rim' of a toilet? Is that the top of the bowl? Sorry, I'm an amateur plumber at best.

The pipe does not have to be straight . . .

If by "straight" you mean vertical, then yes, it does have to be "straight".

So, what is the 'flood rim' of a toilet? Is that the top of the bowl? Sorry, I'm an amateur plumber at best.

Yes, the flood rim is the top of the bowl.

There is no bath above this room (it's a one story house). Looking at it from outside, it is open to a vent above the roofline.

Are you saying that the vent stack must be totally straight top to bottom?

Are you saying that the vent stack must be totally straight top to bottom?

No, just until it is six inches above the flood rim of the fixture.

Growler, thanks for the clarification. No need for us both to be here and you're the pro. See you tomorrow.

Is it common for the vent stack to tie in to the toilet drain under the level of the floor? That goes against my understanding of how the vent pipe works. It would have to be going horizontal to get over to the drain for the toilet. Maybe I'm looking at this wrong, maybe it's not a vent stack? I don't know what else it could be. It's inside this little privacy wall that is between the sink and the toilet.

Is it common for the vent stack to tie in to the toilet drain under the level of the floor?

It is.

The vent is at the junction (fitting) where the drain and trap arm meet.