Question on Venting a basement bathroom and kitchen

[Paul Andrews]

Hello!


I am embarking on finally finishing a basement bathroom and kitchen. I wanted to see if I could elicit some feedback on a question, I had about venting. When I built my house, I had the plumbing for the basement bathroom and kitchen rough in. The bathroom will have a single vanity, a toilet, and a tub/shower. The kitchen will just have a basic sink. Of course, the waste will empty into a sump and pumped into the septic tank. The waste from the basement is the only thing that will empty into the sump. The waste from the top two floors is gravity fed directly into the septic tank.


I have a picture that I took before the concrete was poured that shows the layout of the piping for the system. I have color coded the purposed 2” vent for both sinks as BLUE and the existing 2” vent that runs to the roof in RED. The sump has it own vent piping that I did not show in the diagram.


The question that I have is around venting the lavatory sink, the toilet, and the tub/shower. My plan is to run a 2” vent pipe from the lavatory sink to the existing 2” vent that runs to the roof. However, I am not 100% sure if the tub/shower would need its own vent due to the configuration of the plumbing.


Thanks in advance for your solutions and advice.

 

[wwhitney]

Depends on which plumbing code you are under. Your photo shows the lav drain first joining the WC drain, which wet vents the WC.

Under the UPC, the wet vent has to stop at the WC, so the tub/shower would need its own vent. Under the IPC, the wet vent can continue to other bathroom group fixtures, so the tub/shower coming in next is considered wet vented.

Cheers, Wayne

 

[Sponsor]

 

[Paul Andrews]

Wayne,

Thanks for the information. Alabama follows the IPC statewide.