Basement Drains and Vents - How to properly vent

[matt piggott]

Wondering if I could get some help with proper venting of a shower in my basement floor.
The attached picture is what I uncovered when opening the concrete floor.
The toilet and shower drain need to move to locations shown.
Looks like I need to change the 1.5" drain to 2" for a shower.
Question mainly around the venting.
From what I have read the 1.5" drain with the horizontal dry vent doesn't meet code/ standard plumbing regulations.

What is the best way to re-run the drains and vents for this space while meeting typical codes?
Currently there are two vents on the left which tie together into a 1.5" vent stack higher in the wall.

DrainsVents

• matt piggott
• May 4, 2019

What I uncovered...

 

[frodo]

 

[matt piggott]

Thanks for the quick response. I do have a couple of questions though.
Firs, from what I can tell, you are suggesting a horizontal 1.5" vend from the 2" shower drain until it gets to the vertical portion at the wall. My understanding is that a vent can't run horizontally until it is above (6" if I recall) the spill/overflow area of the fixture that you are venting. So for the shower, I'm assuming that this means no horizontal vents running through the floor. I'm also assuming that this must be for dry vents only.
Second, is it okay to run the shower drain into the 2" sink drain instead of going to the 3" drain. I was hoping to cap the 1.5" line currently in place and tie into the 2".

 

[frodo]

You can not run the shower drain into the sink drain because that is your wet vent for the toilet
the shower has to tie in down stream of the wet vent.

the dry vent off the shower can be run horizontal if it is rolled above the flow line of the drain
if it were a wet vent you would not need to roll it, it could be flat vented

 

[matt piggott]

The original plumbing had the 1.5" routed into the 2" drain just before it wye'd into the 3" drain.
Was this appropriate, but now that the 1.5" is increasing to 2" then it needs to go directly into the 3"?
If this is the case then I'll have to break out more floor to get back to the 3".
And I can't wye off the end of the 3", because the toilet needs to be the last fixture in that line, right?