Another Vent Question

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New Member
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Madison County, Alabama
I've scoured the forum and did not seem to find the exact answer to this question. We are doing a poolhouse and here is my proposed setup.

I see that a bathroom group can have a wet vent in place to service that group (sink, toilet, shower). In the very next room, I have a washer that will have a 2" drain and a wet vent of it's own. It will drain into the main 3" sanitary line (blue shading). That same sanitary line will pass through the bathroom and catch the bathroom group. Will this work? I've drawn a picture. Also, the 2" line from the kitchen is about 18 feet and I don't think it figures into the scenario but added just in case.

All of our codes are 2018 i-codes.

Thank you in advance to this excellent forum. Sorry for my childish drawing.

Second part of my question...Any reason the green portion of the drawing can't "catch" the other vent as it heads upwards?


In the Trades
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Berkeley, CA
In your drawing, the washer standpipe and bathroom sink are being dry vented. The WC and the tub/shower are being wet vented.

Except there is a problem--wet vents are limited to carrying the drainage of bathroom fixtures. So you need to keep the washer drain separate from the 3" line until downstream of the bathroom sink, WC, and tub/shower. Then all is good for the IPC. (The UPC would require swapping the order of the WC and the tub/shower.)

As to the dry vents, yes, they may combine at any elevation that's 6" above the fixture flood rim--which is also the lowest elevation at which a dry vent may turn horizontal.

Cheers, Wayne
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