I am adding a toilet and sink to the laundry room on the first floor and wondering if i need a new vent pipe up through the roof.
The drain run is like this-- 3" toilet drain to basement; 1 1/2' sink drain about 3 feet away. I plan to wye in the sink drain to the 3" from the toilet in the basement. The laundry drain is about 3' down the line from the wye. Then, in another 3', the kitchen sink drain ties in and then about 6' to the stack pipe.
Do i need a vent pipe for toilet/sink/laundry?? If so, where do i put it?
Thx in advance

yes you do need a vent for both toilet and lav.
bring the 3" over for the toilet. put a 3x2 "Y" just downstream of the toilet elbow. run that 2" up behind the sink location. put a 2x1 1/2" sanitary tee for the sink at 19" above the floor and run the 2" up thru the roof or to an available vent stack.
the 2" will wet vent the toilet thru the lav drain.

perfect. thank you very much!!