Basement Bath Plumbing Schematic Review

[T.Chamberlain]

Greetings Gentleman,

I'm finishing my basement and I'm adding a half-bath with an up-flush toilet. Currently, everything is vented through the 4" soil stack but I know I'll need to add a new vent out & up to roof to tie all the new fixtures onto. I plan on cutting out a large section of the CI stack to add a double wye for the kitchen sink and toilet drain. My question is: Is there a better way to drain the kitchen sink and add a vent on that branch that doesn't currently exist? Also, a general review of my diagram for simplicity and compliance would be greatly appreciated. Thank you in advance for any feedback.

 

[Terry]

I think you will want 2" on the venting after you pick up the toilet.
The kitchen sink will need a vent, perhaps an AAV there inside the cabinet.

 

[Sponsor]

 

[WorthFlorida]

You can add an AAV at the kitchen sink trap. If there is no vent now, it must be draining very slow. Check the instructions for the upflush for venting. It might be required to vent directly outdoors and not tied to the house venting and how many fixture unit? A regular toilet is 4 units. Add up the all of the fixture units. You maybe at eight which is the limit for a 1/5" vent pipe. Going with 2" vent pipe would be easier at the sani-tees where the drain and vent are 2" all around. PVC is cheap and barely any cost savings between the two sizes.
https://up.codes/s/determining-drainage-fixture-units

 

[Reach4]

2 inch on the kitchen drain, I think.

If you are on a sewer, and if there is any reasonable possibility of an externally caused sewer backup in the future, maybe consider going full-on overhead sewers. Ask your sewer department if that could happen in a really big rain. If it happens in your area, sometimes towns have programs to pay part of the conversion. All basement waste goes to a septic pit. That gets pumped up. Search for "overhead sewer" in a search engine.

 

[T.Chamberlain]

Understood on the 2" vent. The up-flush is a 3 DFU so with the lav, laundry sink and washer I get 8. The sink is a double bay and it does back-up/ drain slow when the washer is running.