Sluggo
Member
I am designing a small, new bathroom in an area that was previously rough-plumbed as far as the vents and drains are concerned. The bathroom will have a toilet, a sink, and a shower. This area is slab on grade, and I have 1-1/2" ABS coming up through the slab for a shower vent, and there's a separate pipe for the shower drain. There is a 3" drain for the toilet, and there is a 3" vent stack. All of these are connected properly under the slab and all of these pipes are where I would like them to be, except for the 3" vent stack, which is coming up directly under the front edge of where the vanity has to go. I can conceal this 3" vent pipe inside the vanity base where it comes through the floor, but I need to get it over to the back wall so I can run it up inside the wall. I understand I can do a 45 degree jog to accomplish that. However, I would ideally like the stack to take a 90 degree turn right at floor level, run 18" straight back to the back wall and then turn up 90 degrees so it can run up vertically inside the wall and then through the roof. I intend to connect the shower vent to the vertical portion of the 3" stack well above the flood level of the sink, and -- if it's allowed -- I intend to wet vent the sink into the stack since it would be right there. This bathroom will be in a standalone, one-story studio and the only plumbing connection to the main house is the underground sewer system; this 3" stack would only serve this bathroom. I'm in King County.
Bottomline question: Does code allow an 18" horizontal offset of the 3" vent stack below the flood level of the sink as long as the venting of the sink, shower, and toilet are done correctly?
Bottomline question: Does code allow an 18" horizontal offset of the 3" vent stack below the flood level of the sink as long as the venting of the sink, shower, and toilet are done correctly?