View Full Version : Question about toilet venting requirements

10-06-2009, 01:00 PM
Hi All, I'm planning on adding a toilet in the basement of our house, The toilet will be about 24" from a vent stack. I was hoping to hook things up as indicated in the diagram below. Is this a valid way to hook it up? Or will I need an additional vent.




10-06-2009, 01:11 PM
No you will need to vent the new toilet in the basement seperatly.

10-06-2009, 03:57 PM

The downstairs will need to be vented, and the waste from above needs to tie in below the first floor waste.

Helpful Plumbing Hints for Residential Construction by Bert Polk Plumbing Inspector Lincoln County (http://www.co.lincoln.or.us/planning/plumbing/apps/plumbingguide.pdf)

10-06-2009, 04:03 PM
Something like this.

Gold star added by Terry

10-06-2009, 11:25 PM
If that really is a 4" stack with only one fixture on it (a shower perhaps?) on the second floor, then you could wet vent a toilet on the first floor. But a 4" line for just one fixture is overkill....you better verify what is connected to that line, otherwise, you will need to vent that toilet as nhmaster has shown.

10-07-2009, 03:15 AM
No ya can't. You can't wet vent anything with fixtures above.

10-07-2009, 04:42 AM
Hey all, thanks for the feedback. My diagram simplified things a little. There is a toilet, shower and sink above. So I guess I need to find a way to tap into a vent line (I'll have to open up the wall in the floor above)

How far away from the toilet flange can I attach the 'Y' for the vent? I only have 24" before the stack.

Thanks again,


10-07-2009, 05:28 AM
Something like this?

10-07-2009, 06:11 AM
That is one way, but only a physical examination would tell if it was the best way. Where did the lavatory come from? That would have changed the above answers, even the wrong ones.