Maximum developed length of water closet drain.

[Clutchcargo]

While this is still a work in progress and correctable, I came across IPC code that places the maximum developed length for a drain from a WC at 4' or 8' depending on fitting at the stack; respectively Wye, sanitary tee.
I have a WC that is 9' from the stack using a 3" drain but I have a wet vent from the bathtub (2") that Wyes in on that drain line at at about 5.5 feet from the toilet. Is this acceptable by code?
I don't want to find out that this is completely wrong after the walls are finished.

 

[wwhitney]

While this is still a work in progress and correctable, I came across IPC code that places the maximum developed length for a drain from a WC at 4' or 8' depending on fitting at the stack; respectively Wye, sanitary tee.

Oh, what is the reference? That sounds like something from the NSPC, not the IPC.

I have a WC that is 9' from the stack using a 3" drain but I have a wet vent from the bathtub (2") that Wyes in on that drain line at at about 5.5 feet from the toilet. Is this acceptable by code?

The WC fixture drain runs from the closet flange to the first joint with another drain (fixture drain carries only one fixture). I'm not aware of anything in the IPC limiting the WC fixture drain length. The WC fixture drain does need a vent, so if there is no dry vent on the fixture drain, then the tub drain would need to provide a wet vent for the WC. As long as the tub drain is properly vented (via a dry vent, or via a wet vent from a dry-vented lav, meaning the 2" drain carries both the tub and the lav), your scenario is fine.

Cheers, Wayne

 

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[Clutchcargo]

Thanks for the response Wayne. I had a moment of panic as I read code 917.4.1.
I plumbed the tub to a separate vertical vent and then from there to the 3" drain that has the WC upstream. The developed length of the WC drain is 9' with the wet vent entering about 5.5' from the water closet.
The orientation is:
Closet flange --> 5.5' of 3" drain -> Wye fitting (wet vent from tub) --> 3.5' of 3" drain --> Wye into the main stack (4").

 

[wwhitney]

Thanks for the response Wayne. I had a moment of panic as I read code 917.4.1.

IPC Section 917 is "Single Stack Venting". The restrictions in section 917 apply only if you choose single stack venting as your venting approach. The net result is that Section 917 allows venting configurations that would not be acceptable under any of the other sections.

Your configuration is fine under IPC Section 912.

Cheers, Wayne