New bathroom question

[Handyman402]

I'm installing a new bathroom in the basement. From the wye connected to the main sewer line, it will go first the toilet, then the sink, then a shower all in a straight line. Between the shower and the sink i will have an air vent off the drain line, then the sink has an air vent right behind it. My question is do i need an air vent for the toilet? And if so does it need to be between the sink and the toilet, or between the toilet and the main sewer line? The main sewer line is draining 1 bathroom on the main level before it gets to this downstairs bathroom.

 

[Twowaxhack]

I would install one stack positioned between the shower and the toilet.

from the wye continue up your trench with 3” pipe then 45 toward the wall on the right and turn up with a long sweep St 90. On top of the St 90 use a 3x2 left hand Wisconsin (side inlet tee) Position the 3” horizontal hub toward the toilets exact location then turn up with a 4x3 closet ell 90. The vertical coming out of the floor for the toilet will be 4”.

The 2” portion of the wisconsin is then piped with 45’s or 22.5 degree bends to the shower location and a p trap installed.

The top of the Wisconsin rises vertically above the floor and a 3x1.5” tee gets installed roughly 16-18” above the floor to the center of the 1.5” branch of the tee . Your lavatory connects to this.

You’ll only have one vent.

 

[Twowaxhack]

It would be nice if you put a 3” cleanout in the wall higher than the toilet bowl. Just don’t put it behind the toilet tank. You could put a cleanout in your existing pvc too that’s serving the bath above.

If you would use a st 45 to connect to the existing cast iron wye it will keep your pipe in the center of your ditch. It looks like you’re using a st 22.5 fitting there now.

To turn use another 45 to keep the pipe centered in the trench to continue on to the location of your vent.

 

[Handyman402]

so this is what i have so far to give you a better rough idea. So you are saying that i don't need an air vent between the shower and the vanity? And then i don't need an air vent specifically for the toilet? ThanK you very much for the response.

 

[Twowaxhack]

It’ll work. Cover it up.

 

[Handyman402]

What about it is not ideal? What could be better?

 

[Twowaxhack]

What about it is not ideal? What could be better?

I drew it like how I’d do it. There are many ways.

 

[Handyman402]

Got it. Thank you very much for the help