Back to back toilets with proper venting

[tmcnutt18]

I have back to back bathrooms and need to figure out how I can plumb toilets to code in KY. I want to keep the main line up in the joist space so I can finish the ceiling in the basement. The inspector said I can use a double cross tee but if when I add a 90 at the bottom and need to 1/4' fall 20' away this will put line below bottom of joist. I was wondering if I could connect to main line horizontally. Can vents be in main line?

Thanks,
Tom

 

[James Henry]

here's something to try.

 

[Sponsor]

 

[tmcnutt18]

here's something to try.

I tried that. Plumbing inspector said if I didn’t use a cross tee with vent then I have to vent each toilet separate.

Thanks,
Tom

 

[James Henry]

I tried that. Plumbing inspector said if I didn’t use a cross tee with vent then I have to vent each toilet separate.

Thanks,
Tom

I think i'm misunderstanding, what 90 are you talking about? do you mean 20' or 20"?

 

[wwhitney]

The OP is talking about a double sanitary tee (maybe should be a double fixture fitting?) with the inlet and outlet vertical, and then putting a ninety on the bottom to turn horizontal, then going 20' horizontally, and the required fall for that 20' run would put him below the bottom of the joists at the end of that run.

If using a double sanitary tee (or double fixture fitting), would it be allowed to tilt it 45 degrees, so that it would only take another 45 at the outlet to turn horizontal? That would save quite a bit of height.

Cheers, Wayne

 

[wwhitney]

Also, would a flat wye with 2" side inlet be a code compliant way to combine the two horizontal toilet drains, and vent them jointly via the vertical 2" side inlet? This would keep the toilet drains horizontal, unlike using a (double) sanitary tee, which requires a vertical section of drain.

Cheers, Wayne

 

[James Henry]

The OP is talking about a double sanitary tee (maybe should be a double fixture fitting?) with the inlet and outlet vertical, and then putting a ninety on the bottom to turn horizontal, then going 20' horizontally, and the required fall for that 20' run would put him below the bottom of the joists at the end of that run.

If that is what he is talking about, then, he should look up his in local code, in the drainage section, table 704. "slope of drainage pipe".
In the IPC, 3" or larger is allowed to slope 1/8" per foot, that should make it work for him.

 

[Terry]

This is a rough draining. There should be wyes and long turn 90's here, but the concept is there.
Two toilets on the horizontal with one vent works using a wye like the way James showed.