# Horizontal wet vent details



## jogr (Jul 24, 2007)

Under UPC. I’d like to vent a bathroom lav, shower and WC group. Planning on 2” vent/drain for the lav and shower , 3” for the WC drain.
Need some clarity on the slope/elevation requirements for it to function properly as a horizontal wet vent. 
1. Where the 2” shower drain enters the 2” horizontal wet vent does the wye need to be flat and not rolled up at all? (when I say flat I still mean maintaining the ¼” slope requirement)
2. The 2” drain from shower p trap to the horizontal wet vent will be less than 5’. Does this horizontal drain have to be in the same horizontal plane as the wet vent or can it be at a higher elevation and then drop down to enter the wet vent. 
3. Does the 2” portion of the horizontal wet vent have to be in the same horizontal plane as the 3” WC drain or can it be at a higher elevation and then drop down to enter WC drain? Where the 2” enters the 3” must the wye be flat or can it be rolled up (aside from the ¼” slope requirement).


----------



## hammerlane (Oct 6, 2011)

hard to understand what you are explaining. A picture is worth a 1000 words. Maybe mock up what you are thinking and put a picture up.

Here's before on my basement bathroom. First we found the main drain


----------



## hammerlane (Oct 6, 2011)

Here's after. the Toilet is going where the 3" is stubbed up with the yellow plug in it. The toilet is being wet vented off the shower drain. You see the 3x3x2 wye is flat where its picking up the shower drain


----------



## hammerlane (Oct 6, 2011)

Here's another view looking from the shower drain. You can see the 2 inch vent rising up through the plumbing wall


----------



## hammerlane (Oct 6, 2011)

Double post


----------



## jogr (Jul 24, 2007)

Still planning so no pics. You are only wet venting the WC with the lav vent and dry venting the shower. Your horizontal wet vent is on the same plane as the WC drain.

I am asumming that is probably required but trying to confirm. When working around floor joists and trying to maintain headroom there is an advantage to running my 2" horizontal higher and between the joists but the 3" has to be below. Hence wondering if that makes the 2" no longer a wet vent for the WC and so an additional vent for the WC will be needed. 

Another way of asking is "can a horizontal wet vent change elevations?"


----------



## TheEplumber (Jul 20, 2010)

Are you using a UPC code adoption that allows horizontal wet venting? It's rather new to UPC and it may not be approved in your area- depends on your code cycle


----------



## Javiles (Dec 12, 2011)

Is that a sanitary tee on its back for the vent ?? hard to tell also clean out needed at the base of that vent. good job on the completely welded tap no rubber couplings in the ground..


----------



## ben's plumbing (Oct 6, 2011)

not sure of your location...but you could goggle upc wet venting should be section 908.2 will explain the proper set up ... we really don't do much wet venting at all ..but you look like your ok..


----------



## TheEplumber (Jul 20, 2010)

jogr said:


> Under UPC. I’d like to vent a bathroom lav, shower and WC group. Planning on 2” vent/drain for the lav and shower , 3” for the WC drain.
> Need some clarity on the slope/elevation requirements for it to function properly as a horizontal wet vent.
> 1. Where the 2” shower drain enters the 2” horizontal wet vent does the wye need to be flat and not rolled up at all? (when I say flat I still mean maintaining the ¼” slope requirement)
> 2. The 2” drain from shower p trap to the horizontal wet vent will be less than 5’. Does this horizontal drain have to be in the same horizontal plane as the wet vent or can it be at a higher elevation and then drop down to enter the wet vent.
> 3. Does the 2” portion of the horizontal wet vent have to be in the same horizontal plane as the 3” WC drain or can it be at a higher elevation and then drop down to enter WC drain? Where the 2” enters the 3” must the wye be flat or can it be rolled up (aside from the ¼” slope requirement).


jogr, I plumb under UPC and my state recently added horizontal wet venting. But I don't use it since what I've been doing for years works just fine.
With that said, I really can't give you definitive answers, just my best interpretation..

1) yes

2)Same plane as the wet vented section

3) I believe the wet vent can connect to the toilet above the center line.

FYI- here is a link to my horz.wet venting code.
See pg 3, sec.908.2
http://www.iapmo.org/Idaho Plumbing Code/Chapter 09.pdf


----------



## jogr (Jul 24, 2007)

Thanks all, yes my area has adopted horizontal wet venting. The key sentence for me is that it says each drain fixture leg or p trap needs to connect horizontally to the wet vent. 

I interpreted that to mean centerline to centerline but was hoping that I could at least rotate up the 2" to 3" connection to allow for putting the 2" drain above the bottom of the joist level. Doesn't look like that is ok.


----------



## hammerlane (Oct 6, 2011)

Javiles said:


> Is that a sanitary tee on its back for the vent ?? hard to tell also clean out needed at the base of that vent. good job on the completely welded tap no rubber couplings in the ground..


Yes fitting "A" is a San-T on its back used for the vent. I know you cant use a San-t on its back for drainage. Didnt put a clean out at base of the vent rising up in the 2x6 wall.


----------



## hammerlane (Oct 6, 2011)

jogr said:


> Still planning so no pics. You are only wet venting the WC with the lav vent and dry venting the shower.


My lavatory is plumbed in on the other side of the bathroom. we plumbed that in above grade. Also plumbed in for a future laundry sink on the opposite wall of the lav.


----------



## hammerlane (Oct 6, 2011)

jogr said:


> Your horizontal wet vent is on the same plane as the WC drain.


The wet vent..shown in orange... is technically on the same plane as the WC drain disregarding the pitch. 

The WC is wet vented via part of the shower drain. In this photo attached, the pipe marked with green is always vent. It is venting the shower and toilet.

The pipe marked with orange is technically the wet vent because when the shower is running, water(wet) is travelling thru that section of pipe thats marked with orange. But when the toilet is flushed, the section of pipe marked with orange has air being pulled thru it(vent) for the toilet. Im no expert in wet venting but I believe this is correct.


----------



## Javiles (Dec 12, 2011)

Hammer you are correct.


----------



## hammerlane (Oct 6, 2011)

Javiles said:


> Hammer you are correct.


Good to know I have the concept correct. Javiles what's your take on me using a San-T ..... shown as fitting "A"..... on its back to take the vent vertical as shown in post 12?


----------



## hammerlane (Oct 6, 2011)

I'm putting the pic here since my last post was placed on page 1. Hate having to go back pages to look at photos.


----------

