MB Vanity Sinks/Shower

[Gregg G]

New construction, the Master Bath has a "shower only" and double vanity. Is it acceptable
to install double vanity sinks with only (1) P-trap like a kitchen sink? The sinks are against
an outside wall (all concrete with foam insulation), so I'd like to tie the two sinks together,
then have the 1-1/2" trap arm run along the back edge of the vanity to the side wall. The side
wall separates the vanity from the shower. I can run the trap arm so that it's less than 3'-6"
to the vent line san tee (1-1/2 x 1-1/2 x 2).

The shower trap arm will run to the side wall into it's own san tee (2 x 1-1/2 x 2). Then the
shower vent and vanity vents will merge at about 42" above the floor and evevtually tie
into a 3" roof vent. The shower drain will pick up the vanity drain with a 2" wye (wye
pointing up).

Is this acceptable, or do I need to have two traps on the vanity sinks? I can run the trap
arms to the "outside wall" and hot knife out the foam, but I'm trying to minimize building
anything into the outside walls.

Thanks for this great forum! 2nd bath install went well yesterday, but it's tricky getting all of the
3" ABS pipe to line up to glue! Lots of angles and tight fits, but the slip-on trap adapter helped.

 

[Cwhyu2]

Bath sinks must have seperate traps.

 

[Sponsor]

 

[Terry]

The inspector will expect to see 2" going to the double lav with two 1.5" p-traps.
They don't allow two lavs on 1.5"

 

[Gregg G]

The inspector will expect to see 2" going to the double lav with two 1.5" p-traps.
They don't allow two lavs on 1.5"

Ah, I see. So could I use a 2" P-Trap, or is this situation inherently different from a kitchen double sink?

I can do "conventional" like you have shown on other threads, just a little more work getting the vent
into the foam insulation for the wall.

 

[Terry]

You still need a trap for each bowl.