Adding a connection to the main DWV stack

[CanAmSteve]

I want to add a shower and sink in a downstairs bedroom at our cottage. The access to the main DWV stack is as shown - a 3" vertical from upstairs which connects to the sub-slab 4" drain with a 45° wye. I have no major restrictions on reconfiguring the existing pipework other than the location of the 4" pipe in the slab. My intention was to cut off the existing wye and cleanout, add a 4X4X2 sanitary wye for the shower/sink drain and then replace the drain connection and cleanout again in pretty much the same configuration

However, due to the corner location, I am somewhat constrained in how I can orient the 2" drain connection, which needs to be as close to the slab as possible (the finished floor will be about 8" above) to drain the shower pan
Should both the main drain wye connection and the new 2" wye point in the same direction? Obviously waste will travel down the stack at some speed, so should not be directed into another drain. Is there a minimum space between them? I am relatively free to reconfigure the vertical 3" line. I could even reconfigure this to be a straight vertical 4" pipe with a cheanout on a wye arm higher up instead. The pipe takes a 90° bend toward the camera below the slab here, so that might even provide better access. Thanks for your insight

 

[wwhitney]

I want to add a shower and sink in a downstairs bedroom at our cottage.

No WC, just a shower and sink?

Should both the main drain wye connection and the new 2" wye point in the same direction?

Doesn't matter. How are you going to handle venting?

Is there a minimum space between them?

No minimum. You could use a street wye going into a san-tee, that would be as close as you could get them to each other.

I guess if you want something more vertically compact, you could use a 4x4x3x3 double wye (with bushing to make it a 4x4x3x2) if the two side inlets work out being 180 degrees apart. Or if 90 degrees apart would work, you could use a 4x4x4x2 san-tee with side-inlet (with a bushing to make it 4x4x3x2). Then you'd have to use a LT90 at the bottom of your stack, which is maybe less good than a 45 and a wye, but is allowed.

Cheers, Wayne

 

[Sponsor]

 

[CanAmSteve]

No WC, just a shower and sink?


Doesn't matter. How are you going to handle venting?


No minimum. You could use a street wye going into a san-tee, that would be as close as you could get them to each other.

I guess if you want something more vertically compact, you could use a 4x4x3x3 double wye (with bushing to make it a 4x4x3x2) if the two side inlets work out being 180 degrees apart. Or if 90 degrees apart would work, you could use a 4x4x4x2 san-tee with side-inlet (with a bushing to make it 4x4x3x2). Then you'd have to use a LT90 at the bottom of your stack, which is maybe less good than a 45 and a wye, but is allowed.

Cheers, Wayne

Yes - a separate toilet and sink were originally installed under a set of stairs on this level, but there's no space there for a shower.
The original 2" vent line is accessible that was used for the original fixtures on this level (no finished ceiling). There's a toilet, sink, laundry riser and utility sink

Thanks!