View Full Version : Distance to stack

07-21-2005, 04:01 PM
I'm doing remodeling and am looking at a plumbing book which says that the maximum distance to the stack for a two inch drain is five feet. Does that mean the max distance without a vent or, the max distance period? That seems awfully restrictive. I've seen some incredibly long drain lines.

07-21-2005, 04:54 PM
That measurement is from the p-trap to the vent.

The reason for putting vents within certain distances, is so the traps don't siphon out when water is run.

07-22-2005, 03:20 AM
Okay Terry, that makes sense. Just to make sure my understanding is correct: I can have a two inch sink drain eight feet from the main drain as long as the vent from that drain is no more than five feet from the stack. Is that right?

07-22-2005, 09:08 AM
P-trap to the vent.

After you have vented the p-trap, you can go as far as you like.

07-23-2005, 02:41 AM
Okay Terry, now I realize I read your first response incorrectly. Please bear with me here, I want to make sure I get it.
Do I understand correctly that the vent can also be as long as needed? In other words, my sink is eight feet from the main drain. I can connect my vent to the drain line after the P trap and run that vent to the stack. Even though the vent pipe may be more than five feet away from the stack, it is effectively part of the stack since there is nothing ihibiting it between the connection to the drain and the stack. Is that correct?

07-23-2005, 10:38 AM
The distance from the P-trap to the vent is the critical one. The vent can be anywhere from right next to the P-trap to the max allowed. The distance to the stack is irrelevant, as long as it has the proper pitch.

07-24-2005, 02:00 PM
Thanks for the clarification, now I've got it.

06-11-2009, 04:06 PM
I know I'm digging up an older topic here, but is there a MINIMUM distance from the stack to the vent? For example, I want to put the stack and vent within the same 16" stud distance, but because of some other conditions, my vent pipe tee may only be 2-4" away from the sanitary tee that connects to the vertical stack. This vent would be on a 2" line that ran about 18" to a p-trap servicing a clothes washer.

06-11-2009, 08:03 PM
No minimum....vent above, drain below could be an extension of the same pipe.

06-11-2009, 08:29 PM
We might have to see what your plumbing looks like, because if the vent is that close to the vertical riser it may not need a separate vent, depending on other conditions which we do not know about.