Please Help - bathroom Reno venting questions

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New Member
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Ontario Canada
Hi Terry Love plumbing professionals. I need some help on the plumbing layout.

I broke the basement concrete floor for new drains of a bathroom to connect to existing 4 inches drain. The bathroom will have a lavatory, a shower and a toilet. After few days of hard work, I’ve got the pipes installed but now I feel that this may not be appropriately lauded out. Please see the sketch below and let me know if you see any issues and how to fix them.

My initial thoughts are that I will need to have a double wye (somewhere near the current connection to the lavatory “Y”) to connect all 3 drains: the shower, the lavatory and the 3” toile drain. Would this work? Please help. Thank you in advance.


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In the Trades
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Berkeley, CA
The only fixtures upstream of that 4x3 reducer are the 3 fixtures shown?

If so, whether your layout is an acceptable wet vent depends on whether you are required to have the WC join the wet vent last. In the US, one plumbing code does require it to be last (UPC), another does not (IPC). You'll need to check the Ontario code on that point, unless someone else familiar with it is able to comment.

Either way, the total fall on that 4' long 2" shower trap arm, from the trap outlet to the wye, must not exceed 2", the pipe diameter.

Cheers, Wayne
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