Wet venting Bathroom group

[eBrite]

Hello everyone, I am trying to understand wet venting for a single bathroom group and put it into practice on my house build. Can you let me know if this arrangement will work? the double Lav is my vent. I am not sure about the shower at the start of the set up. I have a main 3" branch that is running through the house and this is the start of that trunk. It is a straight run and everything will feed into it including two other bathrooms and kitchen.

Thank you for the help.

 

[Rossando]

Where are you located what state or county? My local plumbing codes wouldn't allow this so I can't help but provide us this and we have people who can help. All I can say is I wouldn't plumb any fixture without a vent in my home or anyone else's. Drains gasping for air is a big no no.

 

[eBrite]

I am located in New Mexico - Bernalillo County.

I think I need to tie in the lav before the toilet. This is a bathroom group and there are provisions for a single vent in UPC 908.2 for wet venting a bathroom group.

 

[MicEd69]

Yes, a lot of people do not understand venting. Your sketch needs to have some dimensions to be able to answer everything. But the way you have it now, the shower is not vented at all. And depending on the lengths of your runs, the toilet may not be vented under UPC. Also, the way the combos enter the branch matter.

 

[eBrite]

Yes, a lot of people do not understand venting. Your sketch needs to have some dimensions to be able to answer everything. But the way you have it now, the shower is not vented at all. And depending on the lengths of your runs, the toilet may not be vented under UPC. Also, the way the combos enter the branch matter.

The combos come in with basic 1/4” pitch from horizontal. If I switch the toilet and lav drain I believe it works as it should. The trap distance from shower to lav tie in would be less than 2’. The toilet to main is ~4’ and lav drain after dropping into floor is about 8’ run but all the tie ins to main are within 2’ of each other.

 

[MicEd69]

Well, that looks like it would work now. But it seems to be some funky sink drain routing just to eliminate a shower dry vent that would also vent the toilet.
I don't know what restrictions you have, and there are 100s of ways to plumb things, but I like things as straight and as well vented as possible. If I was doing this, I would consider something like below, so that the toilet doesn't have any 90s. And while I don't think wet vents are required to enter drain lines from above the centerline of the drain line like dry vents do, I think that is still best practice.

 

[eBrite]

Well, that looks like it would work now. But it seems to be some funky sink drain routing just to eliminate a shower dry vent that would also vent the toilet.
I don't know what restrictions you have, and there are 100s of ways to plumb things, but I like things as straight and as well vented as possible. If I was doing this, I would consider something like below, so that the toilet doesn't have any 90s. And while I don't think wet vents are required to enter drain lines from above the centerline of the drain line like dry vents do, I think that is still best practice.
View attachment 48060

I am running parallel up in I-Joists (each fixture is separated by a joist) and cannot cut across them due to being at the end of them and restrictions in cutting at the ends. They meet up with floor trusses that I can run perpendicular through without drilling so that is why I am running the main trunk through there. The lav sits back far enough to drill to the bay with toilet so I am coming 45 to there and ending up before the toilet.

 

[MicEd69]

I am running parallel up in I-Joists (each fixture is separated by a joist) and cannot cut across them due to being at the end of them and restrictions in cutting at the ends. They meet up with floor trusses that I can run perpendicular through without drilling so that is why I am running the main trunk through there. The lav sits back far enough to drill to the bay with toilet so I am coming 45 to there and ending up before the toilet.

Understand about the joists. So, you are getting the sink drain over to the toilet "bay" without any problem. I would suggest dropping the sink drain into the toilet branch above the centerline of the drain and still run a dry vent up for the shower. That would, in my opinion, give you a better DWV system.

 

[eBrite]

Understand about the joists. So, you are getting the sink drain over to the toilet "bay" without any problem. I would suggest dropping the sink drain into the toilet branch above the centerline of the drain and still run a dry vent up for the shower. That would, in my opinion, give you a better DWV system.

Ok thanks for all the help.

 

[Ludington]

I thought a toilet needed a dedicated vent within a few feet.

 

[MicEd69]

I thought a toilet needed a dedicated vent within a few feet.

UPC requires a water closet vent to be within 6 feet of the toilet, which is what the OP is under. IPC just requires that there be a vent somewhere in the plumbing system.
And something that I didn't mention to the OP was that the wet vent line needs to be 2" and that 2" needs to be up through the roof or connected to the main vent stack.

And after thinking about it for a while, my recommendation about "dropping the sink drain into the toilet branch above the centerline of the drain and still run a dry vent up for the shower" may actually be a requirement to properly vent the toilet. The OP should check with the AHJ if he wants to do it per his sketch.

 

[jrodd]

This is how I just did my new house. It's in Tucson, AZ (IPC) and on a slab so easy to lay out. I've done horizontal wet venting in a crawl space in WA as well (UPC) but usually find it too difficult in second floor joist bays.

 

[jrodd]

And while I don't think wet vents are required to enter drain lines from above the centerline of the drain line like dry vents do, I think that is still best practice.

A horizontal wet vent can not enter above the centerline, that would be a big fail. The entire group has to be in a flat plane, other than the 2% fall.