Hello. I have two tricky situations. The first is a definite code violation. I need to use a wye instead of a sanitary tee for my connection to an upstairs toilet. The problem is that I can't fit a wye through the floor joist without completely cutting through the joist. A sanitary tee will fit, but it's going to require a lot of bracing.



The other problem is that I needed a vent for a bathtub and I need to know if it's okay to use two 90 degree vent elbows hub to hub before running up vertically. That would be about 1 1/2" of a horizontal run. Thanks in advance and the cuts on the sanitary tee were pre-existing.

The tee for the toilet looks correct to me. It is a 3" dry vent above the tee correct ? A wye would create a partial S-trap which is a code violation.
The 2 90's on the vent is a code violation, you have a dry horizontal vent below the flood level. The tee is backwards as well, it needs to sweep in the direction of flow. If you could use a 45 and roll the tee so it's on a 45 it would be code compliant.

There's more problems than you stated. In pic 1, the proper fitting for that toilet shown to the stack is a sanitary tee. The pipe that comes down into the top of that tee can only be a vent for that toilet or drain for another fixture on the same floor as that toilet and the pipe would continue up as the vent. You can't drain a toilet from an upper floor into that stack, unless you vent the lower toilet separate from the stack. In pic 2, you can't use a sanitary tee on it's back at that location (and it's also backwards). You need a wye or combo fitting there.

Thanks! So the sanitary tee is fine. I could have swore it required a wye. The second problem is the two 90 degree elbows. I tried to use 45's first, but there just wasn't enough room. I'll go back and see what I can do.



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You can't use a sanitary on it's back for the tub vent and the vent for the tub only needs to be 1½"(actually 1¼", so you can pick up some extra room with the smaller diameter vent.



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The toilet drains into the 3" stack vent. The toilet below has a 2" cast iron vent. I'll correct the tees' as they're just dry fitted. So hopefully that will be fine. My problem after that will be attaching a 1 1/2" vent from the bathroom below for the tub and vanity.

Thanks again. Both you guys are helping me a ton and I really appreciate it. So the sanitary tee has to be verticle when you vent like this one:




Does that apply to all venting situations? Please don't tell me I need a wye here in this pic. Good thing it's dry fitted.

You say I can use a wye in my second pic to vent the tub and then use a 45 degree elbow and straight on up the innards of the wall. I'll switch it out to 1 1/2". It's only 2" because I thought I was originally going to wet vent the toilet there as well.

Almost forgot! The wye can be on it's back, correct?



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A wye or combo tee/ty can be installed on it's back, regardless of where it's being used. The sanitary tee in pic 3 is the proper way to install when used as a drainage fitting. When a sanitary tee is used as a vent fitting, installed not less than 6" above the flood level of the fixture it's venting, it can be on it's back. Any vent piping/fittings installed less than 6" above the flood level of the fixture it's venting, need to be installed as if they were for drainage.

I think I understand. I thought you were saying something else for a minute so I had to edit my post. Here's the solution I think I've come up with for the second photo to vent the tub correctly. I was able to fit it in the wall without too much difficulty:




Sorry about that last photo. That's my dog's photogenic behind.



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It's a matter of the orientation(standing up vs on it's back) of the sanitary tee as to where it's permitted. The flood level of a fixture is the height that water will spill out onto the floor. Codes specify any piping less than 6" above the flood level are to be considered as drainage and installed with fittings and pitch that are proper for drainage.

Gotcha! I'm starting to wind down... It's after midnight here. So did my solution look like it would pass? That should be the ccorrect orientation for the wye. If not, I'm making a run to the hardware store in the morning and I'll pick up anything you recommend. I accidentally put in a regular 4" elbow on my only major turn instead of a long sweep so I have to go buy one and replace it. Unfortunately I did glue it because I didn't realize it at the time. Thanks again for the help tonight. You've also helped me with some other things I was uncerrtain of as well. I might make a new post tomorrow of my dry fitted laundry room/kitchen just to be certain I've got it configured correctly. I think I do, but it's best if someone else sees it before I glue it all together.



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