Venting toilet

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I'm getting ready to plumb my bathroom on my second floor. I would like to do only one roof penetration for the vent, the second floor isn't a full floor and has a sloping roof, some if the bathroom had a sloping ceiling, which makes running vents overhead challenging.

The toilet will sit on the opposite end of the bathroom as the main vent. The main vent is going to be a 2" stack behind the vanity. The total distance from the toilet to the wall with the stack is 8'.

The toilet and shower sit on the same wall opposite of the sink.

In the attached picture the red line is the 3" toilet, blue is 2" shower, green is 2" sink, orange dashes are proposed vent overhead, and the purple circle is where the vent will penetrate through the roof and everything will be tied together.

My idea was to use the 2" shower drain as a wet vent, back to the wall where it would then be able to go up into the ceiling space, then over to tie into the main stack. Is this a legal way to do this, or would I need to add another vent for the toilet?

Thanks a bunch.


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