Quest for garage urinal continues, but need advice about tapping into horizontal main septic line.

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Cornets77

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Hello all,

I’m a DIY’er who’s installing a garage urinal and hoping to get some advice on teeing into the main septic line in my detached garage. Per the specs on the urinal, I need to have the drain outlet at 12 1/4” from the ground for an ADA set up and 19 1/4” from the ground for a “standard” set up. I’m not a tall person so I was hoping to keep it around 20” or so.

Anyway, the main septic pipe I’d like to tie into is a 2” horizontal ABS pipe within the wall. The problem is the pipe is already 21” off the ground and I can’t modify it’s height further down as there isn’t any room to maintain the appropriate slope for drainage before it hits the concrete of the foundation.

A combo wye attached to a male adaptor placed horizontally would keep an acceptable height, but it protrudes from the wall by a significant margin. A vertical sanitary tee with the adaptor maintains appropriate depth, but is too high. I’d love to use a horizontal sanitary tee, but read this is against code, but not sure why.

This is a Toto unit that uses only 1/8 gallon per flush, so this thing won’t see large volume or any solid waste obviously. Any thoughts on making this work? Worst case scenario I put a step stool in front of it, but I’m really trying to avoid it.
 

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Jeff H Young

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you need a vent as well . 24 inches isnt that high youve got the urinal see how high is comfortable 24 is still not high
 

Tuttles Revenge

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Well we know that the lowest that your drain can be is 21" so one way to do it and have a vent on the trap as Jeff points out. You have seen how far out a Combi on its side would be too. So lets look at how we can minimize the bump out of the wall. What I propose is to cut in a Horizontal WYE that protrudes from the wall with a 45 that brings it parallel with the existing drain. That needs a vent which needs to be a vertical branch pointed at 45 upwards back into the wall. The horizontal branch of that vent fitting extends to a 90 that the drain fitting attaches to for the urinal. Build a bump out wall to that dimension.

1707503152731.png
 

Cornets77

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Well we know that the lowest that your drain can be is 21" so one way to do it and have a vent on the trap as Jeff points out. You have seen how far out a Combi on its side would be too. So lets look at how we can minimize the bump out of the wall. What I propose is to cut in a Horizontal WYE that protrudes from the wall with a 45 that brings it parallel with the existing drain. That needs a vent which needs to be a vertical branch pointed at 45 upwards back into the wall. The horizontal branch of that vent fitting extends to a 90 that the drain fitting attaches to for the urinal. Build a bump out wall to that dimension.

View attachment 97137
Thank you so much for the diagram and advice! I think bringing it out from the wall will be the way I have to go. Would I still need a vent if I only used a combo wye directly into the urinal drain or would this result in unnecessarily long drainage as the displaced air would have to come up the urinal drain?
 

Jeff H Young

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Definately need a vent from a code point of view evedently there is talk here that AAV are supposed to have some legal use in Washington . whether a urinal horizontal wet venting off a sink next to it (illegaly) will work properly I dont know but Id expect it might function descently I wouldnt recomend it though
 

Cornets77

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Well we know that the lowest that your drain can be is 21" so one way to do it and have a vent on the trap as Jeff points out. You have seen how far out a Combi on its side would be too. So lets look at how we can minimize the bump out of the wall. What I propose is to cut in a Horizontal WYE that protrudes from the wall with a 45 that brings it parallel with the existing drain. That needs a vent which needs to be a vertical branch pointed at 45 upwards back into the wall. The horizontal branch of that vent fitting extends to a 90 that the drain fitting attaches to for the urinal. Build a bump out wall to that dimension.

View attachment 97137
 

Cornets77

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Thanks again for the advice. I haven’t glued anything in place yet except for the combo wye. It stands out ~ 10” from the wall, which isn’t ideal, but I’ll be building a box around it. Any other thoughts before I commit this thing in glue after I build the box?
IMG_2793.jpeg
 

GReynolds929

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Tee on its back for AAV should be a combo and go in direction of flow. Need to have shielded couplings at the combo tie in, not the unshielded that are there.
 

John Gayewski

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The aav will need a grate that can let air into the piping. You may have already said that you were planning for that, but I haven't re-read the whole thread.
 

John Gayewski

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Generally for a urinal your gonna want plenty of room to adjust the length of your threaded adapter. The urinal comes with a brass flange and needs to sit tight onto the wall. Watch for that. We usually use a threaded schedule 80 nipple and cut it to the correct length after the wall is done.
 

Jeff H Young

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From the 2 pic the combi appears backward as well ? maybe an illusion.
Sounds like John means glue one side nipple in the fitting and other side threaded Great Idea ! I never piped a urinal in plastic
 

Cornets77

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From the 2 pic the combi appears backward as well ? maybe an illusion.
Sounds like John means glue one side nipple in the fitting and other side threaded Great Idea ! I never piped a urinal in plastic
Yeah, it was. Corrected the issue, but couldn't find shielded couplings at the local big box store to replace the Ferncos. Also, pipe glue drying got away from me before I could adjust the angle on the trap arm. Amateur hour, I know, but I really do enjoy learning how to do stuff like this. Takes me probably 10x as long and 10x the number of trips to the store compared to a pro, but it's my hobby. I'd like to say I'm saving money by not hiring someone, but between wasted ABS and all the time invested, I know it's probably a wash.

IMG_2797.jpeg
 
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Cornets77

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Generally for a urinal your gonna want plenty of room to adjust the length of your threaded adapter. The urinal comes with a brass flange and needs to sit tight onto the wall. Watch for that. We usually use a threaded schedule 80 nipple and cut it to the correct length after the wall is done.
Makes sense. I'll be building the enclosure for the exposed ABS with the back wall positioned to fit the brass flange/traparm, but great tip when I'm working with a back wall I can't adjust. Also, thank you about the advice for the grate for the aav. I'll probably have it go straight up now vs angled back into the wall cavity like the picture so that I can put a grate on the side of the enclosure.
 

Jeff H Young

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To me there is a lot of value to learning how to do something yourself If this was the only plumbing youll ever do might not be worth it , sometimes its frustrating but stick with it !
 
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