Shower, tub drain and vent - is this OK (code compliant?)

[Johnson T.]

Hi, as part of my remodel I am moving the shower too to where a single sink used to be. The floor joists limit my options a bit as the (old) drain line runs almost in the middle of the new shower location.

I also want to add an emergency floor drain (if I get water on the floor there will at least be a drain I can push it to). So for the given 3 drains I want to have, are there any issues with the distance to the vent or how I have the connections?

Black lines are old / existing pipes; blue are planned new pipes.

Thanks!

 

[wwhitney]

Neither your old layout nor your proposed layout is properly vented. Every trap need a vent, which may be wet or dry. Wet vents are drains that carry at least one dry vented fixture drain and, in this context, that carry only bathroom fixtures. And a dry vent has to connect to a drain carrying only 1 or 2 fixtures (for the IPC).

So to vent your new layout, you could add a dry vent or a wet vent. A dry vent would need to come off the upper half of the drain and rise (meaning at least 45 degrees above horizontal) until 6" above the flood rim of the fixture(s) served. So usually the drain is routed under a wall so the vent can rise into the wall. This dry vent could be connected anywhere upstream of the wye where the tub/floor drain joins the shower, but needs to be within one trap diameter of fall from the tub and the floor drain. Since the fall rate is at least 1/4" per foot, that give you a maximum developed length from the trap to the vent. The combined tub/floor drain would then wet vent the shower.

For a wet vent, you'd bring in a dry vented fixture, like a dry vented lavatory which your new diagram omits, and connect its drain to either the tub drain or the floor drain before the wye where they join. Then the lav would wet vent the tub, the floor drain, and the shower.

BTW, your emergency floor drain requires a means to avoid the trap drying out. Under IPC 1002.4.1, that can either be a trap primer (e.g. a device so that whenever you flush the toilet, a small amount of potable water is sent to the floor drain trap) or a "Barrier-Type Trap Seal Protection Device" conforming to ASSE 1072, which is not something I'm familiar with but sounds easier to install.

Cheers, Wayne

 

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[Johnson T.]

Wayne, thanks a lot for the detailed answer.
I will spend some time later this week to think through it. I have another vent close by and I think I can connect it to the tub/floor line. I'll sketch something out.