2 water closets back to back

[mtcummins]

Again, don't want to argue, particularly if Canadian code is different here, but I don't think you have to separately vent the 2nd toilet. Correct me if I'm wrong.

That said, it certainly wouldn't hurt anything, you'd do a 3x3x2 wye/45 to a 2" vent after the 2nd WC, then take it up above the highest flood plain (typ. 42") and tie it into the 3" vent with a santee (upside down).

Can someone give insight about the venting issue? I'm pretty sure you can put 3 WC on a single 3" line, with the vent between the first 2, and need no further venting, but I could be mistaken.

What I WOULDN'T do, is put both toilets into a double santee. Too many problems with that setup with today's toilets...

[mikeplummer]

a 1-1/2" back vent on downstream toilet is all that you need..and yes connect to the 3 " above FLR of lav

[poky1234]

a 1-1/2" back vent on downstream toilet is all that you need..and yes connect to the 3 " above FLR of lav

Could the backvent on the downstream toilet be a 2 inch wet vent coming from the tub? Thanks

[mikeplummer]

as long as the tub is connected as a vertical continuos waste

[poky1234]

as long as the tub is connected as a vertical continuos waste

Thanks Mikeplumber, I'll proceed like that with the tub with a vertical continuous waste vent , venting the downstream toilet. One last question if I may, When you turn 90 % horizontally on a horizontal waste pipe can you use a long sweep 90 elbow or 2 45s ?

Thanks again.

[mtcummins]

The easy rule is, anytime you turn TO horizontal (whether from vertical or horizontal), use a long sweep 90 or 2 45s. Turning to vertical you can use a medium 90.

A trap arm, I think, can break this rule and use a medium 90 to stub out of the wall. That's the only time I'm aware of a waste line being allowed to be medium 90 going to a horizontal.