Venting a shower and separate tub

[Chas1057]

I am installing along the same wall a shower drain, then four feet over to a tub drain, then four feet over to the main 3' drain going down and vent going up thru the roof. Where should I vent the show/tub drain . Before the shower trap? Or in between the shower trap and tub trap , then up thru the attic and roof.

 

[Tuttles Revenge]

A typical tub requires a 1.5" trap and trap arm to a 2" drain. But that trap arm distance is limited to 42". If you have a 2" trap for the tub, then its trap arm extends to 60" to the stack. The shower is horizontally wet vented in your drawing assuming you use the 2" trap at the tub. At least in the UPC. Not sure what code your area of NJ follows.

 

[Sponsor]

 

[Chas1057]

Where should I vent? Before the shower trap, or in between the shower trap and tub trap

 

[Dustbunny]

Between the tub trap and the drain. Vents are to prevent siphoning of the traps.

A 2" line can run 8' before it needs to be vented.