How do I plumb back to back WCs? The IRC restricts the use of a double sanitary T for WCs. Is there another combination of fittings that are acceptable such as a double Y? I will have 10" floor joists and a 2x6 wall between the 2 WCs.

The IRC does allow the double sanitary T if the "horizontal developed length between the outlet of the water closet and the connection to the double sanitary tee is 18 inches or greater." Is the 18" measured from the center line of the WC flange to the center line of the stack or is it measured between the hub of the T to the hub of the elbow on the WC?

Yes, you can use Double Y. It is commonly used in back-to-back wc installations. See image...

Milo...

That isn't any double wye I know of... That is a double combination wye 1/8th fitting. I can, however see how an inspector would allow this fitting!

Moosehead, if you want the toilets directly back to back with a 2"x6" wall between them then you cannot satisfy the 18" rule you mentioned.

See if your inspector will allow the double combination wye 1/8th fitting... let us know will you.

Thanks...

MARK

Mark, that's exactly what I was trying to say...

In my area, some inspectors ask for dbl Y because in case of cloggage, snake will not travel across to the opposite toilet but will be guided downwards...

I hear you Milo... same here, but that fitting you posted isn't a double wye... that's all I was saying... ;)

Hey, can I PM you with another issue I need help with?

Let me know... ok?

Thank you.

I hear ya Milo...same here, but that fitting you posted isn't a double wye....that's all I was saying...;)

Hey, can I PM you with another issue I need help with??

Let me know...ok??

Thank you.

Sure, PM me... ( in the meantime, I have to figure out how to receive PM's... :eek: )

At the very upper right of the screen/upper page there should be a private message icon under your name.

It will blink when you get a PM... I think... ;)

Writing now

I will go to the inspector with the double combination Y 1/8 fitting and see what he says. Thanks for the quick replies.

Let us know what he says...

Thanks...

MARK