I want to install a vanity sink and a toilet and a small shower in the east end of my bungalow. The bungalow has a relatively new steel roof, and I so don't want to vent through it. I want to vent through the east wall. My plan is to have all 3 items connect to a new waste water pipe in the joist cavity under the floor, which will connect to the rest of the house plumbing on the west side, to carry the waste water away. Can I use the new waste water pipe that collects the waste from the vanity sink and the toilet and the shower as a wet vent if I extend the waste pipe and turn it up through the east wall plate, up inside the wall, and out the wall at about the 7 foot point, with an appropriate cap?

You need to use the sink vent as the wet vent for the entire bathroom group... not just the drain line. Can you run the sink vent back to the east wall?

Mark

You need to use the sink vent as the wet vent for the entire bathroom group... not just the drain line. Can you run the sink vent back to the east wall?

Mark

Thanks for the reply. Please look at my rough diagram plan. I was hoping the extended new waste pipe in the joist cavity would provide enough venting for each of the items. 3" waste pipe into 2" vent pipe up through the exterior wall.

The sink MUST BE VENTED... it is this vent that will "wet vent" the other fixtures.

Thanks for the feedback. As I cannot vent through the roof, and it would be very difficult to vent the kitchen sink out the east wall, I would like to use an air admittance valve from Lowe's [Studor brand product # 671806 about $40] Hopefully this could do the work of an external vent.

An AAV is better than no vent. As long as local plumbing code allows, I'd install it at the sink. Take the sink drain directly off the toilet drain and install the AAV under the sink.

Thank you for the feedback - and for giving me the feeling that the real solution is to find a way to have a "real" vent, not just an "AAV". After some careful thinking and planning, I found a way to run a vent from the vanity sink waste pipe, up inside the wall, then along the wall heading east, along (inside) the east wall about a foot where I was able to have the new vent exit through the exterior wall. Looks good. Going to be the best solution.

Yeah, as a licensed plumber, I know there is ALWAYS a way to get a vent run. Good job!