# Illinois Venting Question



## UA25 (Jan 11, 2013)

Ok, Section 890.1500 Installation of Wet Venting.

If I'm reading this correctly a single bathroom group of fixtures. Water Closet, Lav and Shower could all be wet vented through a 2" diameter pipe say through the lav. And it meets the requirements for DFU's and horizontal branch drain being 2". Also, this is an upstairs bathroom so the 
3" stack vent would be behind the toilet. 

I hope I explained myself well enough. Just looking for some insight.

Thanks,
R


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## LIQUID (Sep 26, 2013)

Typcally bathroom groups are wet vented through the lav ( 2" wet vent serving the wc. ) the w.c. is 3" obviouslly, a 3 x 2 wye is talen off and a 2x 1 1/2 wye taken off of that to pick up the tub. The dry vent above the wet vented portion of the lav can be reduced to 1 1/2 I am not sure why you mention the stack vent In this ? Every domestic dwelling must have at least 1 3" stack ( vent ) that continues through and is increaded to 4" at roof penTration, this is to vent the sewers.


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## LIQUID (Sep 26, 2013)

You can stack vent a wc. But that would be the only fixture served by the stack vent. Since you need to serve every trap with a vent you require either individual vents for all ( best but most expensive ) or a wet vent properly sized. Typically in the installation you describe the dry portion of the wet vent 1 1/2, would be tied into the stack vent using a 3 x 1 1/2 wye ot t wye above flood level (There would only be a single roof penetration). Hope this answers your question.


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## Ryan M (Dec 8, 2013)

When push comes to shove go over kill and individually vent each fixture if your unsure. When the floor is down and the walls are up you don't want to have to install a cheater vent.


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