Adding Shower to existing toilet drain

[Keith Kassen]

Hello all, i'm looking to add a shower to our powder room. Is it possible to add a shower drain to the existing toilet drain? My plan would be to move the toilet to the left about 36" and then place the shower in the toilet's original location. Could I cut the line for the toilet and place a long turn tee wye. Or would this create a syphon problem for shower drain. The picture is from below the toilet, also I no longer have access to this area. All work would from above by removing the floor.

 

[Tuttles Revenge]

Yes. You can do it easily by utilizing Horizontal Wet Venting. If your new toilet location will be where drawn, you could add a Combination WYE / 45 (combo) fitting where the 90 up is now. Point it to the toilet. Pick up the toilet with a WYE. Reduce to 2" for the shower and to the Lav. Maintain 2" vent at the sink and take it up through the roof or combine with the original 3" vent.

 

[Sponsor]

 

[Keith Kassen]

Yes. You can do it easily by utilizing Horizontal Wet Venting. If your new toilet location will be where drawn, you could add a Combination WYE / 45 (combo) fitting where the 90 up is now. Point it to the toilet. Pick up the toilet with a WYE. Reduce to 2" for the shower and to the Lav. Maintain 2" vent at the sink and take it up through the roof or combine with the original 3" vent.

View attachment 94960

Thanks for the response. If the Lav already has a drain and vent, do I need tie into it or can I just stop at the toilet? Or does the toilet need a vent in front of it.

 

[Jeff H Young]

normally wying off a w/c "trap arm" is prohibited not sure if that rule went away since venting has changed with the allowing of horizontal wet venting , of cource Keith it wont be a horrizontal wet vent with modification you propose . I cant find exact code at momen but it was always against code could have changed though good question I need to review for my own for just general knowledge as well !

 

[Jeff H Young]

BTW Keith the W/C already has vent (presumably at the wall) but no other fixture was allowed to tie into the trap arm unless there been that change , you could of cource add a santee on top of the santee for the w/c and vent shower that way

 

[John Gayewski]

Thanks for the response. If the Lav already has a drain and vent, do I need tie into it or can I just stop at the toilet? Or does the toilet need a vent in front of it.

What size is the existing vent for the lav?

 

[Keith Kassen]

What size is the existing vent for the lav?

2"

 

[John Gayewski]

Then you're whole bathroom can vent from the lav as shown in tuttles drawing. But everything in the bathroom needs to be tied together.

 

[Keith Kassen]

ok great, thank you for the help.

 

[wwhitney]

The sanitary tee in your photo, does it have the lav drainage coming down from above, and nothing else? I'm going to assume yes for now.

Just to clarify, tie everything together but the lav can't be last. I.e. you can't run the shower trap arm to WC trap arm, and then have both of them hit that san-tee with the lav drain coming down. You'd need to have the lav join the shower first, then join the WC. I.e. put in a san-tee for the shower above the san-tee for the WC (or put in a new san-tee for the WC below the existing san-tee if you reuse the existing san-tee for the shower only).

Cheers, Wayne

 

[Keith Kassen]

There's nothing but the vent above sanitary tee. It goes up about 42" and then all the vents connect to one vent then goes out of the roof.

 

[wwhitney]

There's nothing but the vent above sanitary tee. It goes up about 42" and then all the vents connect to one vent then goes out of the roof.

OK, in that case if you want to tie both the shower and the WC into that stack, you still need two separate san-tees on the stack, an upper one for the shower, and a lower one (could be a wye) for the WC.

Or you could reroute the lav drain (presumably it currently ties into the stack below the san-tee for the current WC), and use it to horizontally wet vent.

Cheers, Wayne

 

[Jeff H Young]

stacking a tee for shower might be too high . horizontal wet venting should work if tuttles drawing is not correct then a 3x3x2 wye could be used and lav wouldnt be last