Wet Venting

[firescreamer]

Hello everyone,

I just had a plumber finish a basement bathroom rough-in job (we're located in Illinois) and noticed that the basement lavatory drains into the vent for the water closet. Asking the plumber about this I was told that you can have one wet vent in your system which meets the standard in the plumbing code but that he would not mention it to the inspector when he comes since not all inspectors inspect the same. Seems like a terribly strange to thing to tell someone...

Relevant links to Illinois plumbing code are below:
Section 890
http://www.ilga.gov/commission/jcar/admincode/077/07700890ZZ9996kpR.html
PART 890 ILLINOIS PLUMBING CODE : Sections Listing

 

[LiQuId]

I cannot speak for illinois but where i am it is common for a bathroom group to be wet venter through the lav, it must be a 2" pipe to serve the Water closet and must be a minimum of 1 1/2 " above where the lav ties in on a vertical t-wye ( sani T ) for the dry portion of the wet vented branch. It does sound strange to tell someone that but I believe from the description that your plumber did the job correctlly.

 

[firescreamer]

There is an underslab 4" drain for the water closet with a 2" vent sitting on that branch. The lavatory drain (2") connects to the water closet vent. The vent then vertically with the vent (1-1/2") from the same lavatory connecting to it 24" above the lavatory drain connection. The kicker is that I had another call from him today in the morning where it sounded almost as if he was trying to dissuade me from having the inspector come out before everything in the bathroom was done. If the inspection does fail because of this, it will be a big mess as quite a bit of the plumbing work would have to be redone.

 

[LiQuId]

from your discription it will pass, a toilet does not require a second vent if the bathroom group is on a branch from the main line and it has a 2" pipe serving the lav that reduces to 1 1/2 " above the point of the t-wye.. this configuration can also wet vent a tub through the 2" serving the lav if the Tub trap arm is connected to the 2" branch... it will fail if the tub branch comes off of the 3" ( in your case 4" ) branch seperatelly.

ALWAYS have it inspected.

 

[Pipedawg]

it will fail if the tub branch comes off of the 3" ( in your case 4" ) branch seperatelly.

ALWAYS have it inspected.

Not true. If the tub branch comes off the 4" separately and the lav is in between the toilet and tub that is a circuit vent and will pass inspection.

 

[johnjh2o]

Not true. If the tub branch comes off the 4" separately and the lav is in between the toilet and tub that is a circuit vent and will pass inspection.

What liquid is saying is it would fail if the tub connected to the 4" separately. Not to the same fitting serving the lav and the toilet vent.

John

 

[Pipedawg]

What liquid is saying is it would fail if the tub connected to the 4" separately. Not to the same fitting serving the lav and the toilet vent.

John

I know what he is saying and that is sill incorrect where Im from. I know all states don't allow circuit vents but that's how they work. You have 4" run you throw a 4x2 wye for the tub then another 4x2 for the lav then a 90 for the WC. 2 to 8 fixtures. Vents can be wet and must in between the two most upstream fixtures. If you have 4 or more you have to add a relief vent at the end. Totally legal in Wisconsin. So either way it will pass.

 

[LiQuId]

hmmmm, odd.. circuit venting is different everywhere you go so it may well be legal where you are to do it in that way. here, what you describe would still be considered a wet vent and would fail for a few reasons. a circuit vent ( here ) requires 2 vents to form the circuit vented branch, one at or immediatelly downstream of the most upstream fixture ( the releif vent ) and allows for up to 8 fixtures before additional circuit vents are required also a branch upstream can be used as a alternate releif vent as long as it does not have a fixture load greater than 6 FU's. also 2" and lesser traps must be seperatelly vented. the circuit venting part of our code book is 6 pages if memory serves. just goes to show that plumbing is diverse across different locations