Straight stack down to lower story or bend into lower story stack?

[PeteC]

I am planning the DWV for a two-story house in Lincoln County Oregon using UPC code. The county has a "plumbers guide" with photos. I'm trying to make sense of one thing.

They have a several photos of the drain stack from the upper story going down to the lower story and bending into a lower story stack.
They never have photos of the upper story stack going straight down and the lower story stack bending into the upper story stack. Is there a reason they choose to wye into the lower story and not have the lower story wye into the upper story stack? Slow down the waste?

Hope this question is worded okay. Thankyou.

 

[PeteC]

I am planning the DWV for a two-story house in Lincoln County Oregon using UPC code. The county has a "plumbers guide" with photos. I'm trying to make sense of one thing.

They have a several photos of the drain stack from the upper story going down to the lower story and bending into a lower story stack.
They never have photos of the upper story stack going straight down and the lower story stack bending into the upper story stack. Is there a reason they choose to wye into the lower story and not have the lower story wye into the upper story stack? Slow down the waste?

Hope this question is worded okay. Thankyou.

I would rather have the plumbing flow along the red lines in the lower photo. Will this work?

View attachment 81848

 

[Sponsor]

 

[John Gayewski]

They are showing a drain and vent. The pipe on the right is a vent going from thre first floor to the second floor. This vents the trap arm on the first floor. The drain portion from the second floor is wye'd into the lower drain portion. The vents come back together safely above the drains.

I'm not totally sure what your asking. You can't drain into a vent between two floors. You can drain straight into the piping from the second floor to the first, but it's aless optimal way. Dropping water that far can cause some undesirable things but it's mostly fine. Depending on what your draining. Sudsing could be a side effect.

 

[Terry]

Picking up the basement kitchen on the wye works fine. Either way, it's vented, and revented on the second story. It works.

 

[PeteC]

Thank you John and Terry. Because of the fact that it "depends on what I am draining", I created a more accurate rendering of what I want to do. Basically, draining a bathroom from the upper floor 10 feet above (8 foot ceilings and 24" truss floor). And on the lower floor I want to tie a laundry sink into that stack. I wanted to have the bath stack go straight into the concrete to keep the plumbing further away from the grade beam on the edge of the monolithic concrete slab.

 

[wwhitney]

That's fine. Which way the wye goes in your second post (as in photo, or as drawn in red) doesn't matter at all. Further comments on your drawing:

- Laundry sink only needs a 1-1/2" vent, but a 2" drain, so a 2x1-1/2x1-1/2 san-tee behind it would suffice.
- The diagram makes the fittings on the horizontal line from the bathtub look like san-tees, they both need to be combos.

Cheers, Wayne

 

[PeteC]

Thank you Wayne.
Thanks for the detailed response.
Yes, no san-tees on their backs! (even though the internet has images of it all over the place!)

Cheers, Peter