Help with yet another bath drain configuration please and thank you.

LocalHero said:

Dang it Terry, I thought I was going to understand your answer! Do you mean to say it wouldn't be wet vented if one or more of the lines were sized differently? And is wet venting the same thing as "S trapped?

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Sizing does not determine if it's wet vented or not. If a fixtures vent receives the discharge from another fixture then its wet vented.

S trap is where the outlet of the trap(weir) extends below the bottom of the trap(j-bend) before it hits the vent. This is why pipe size has an effect on the distance the trap can be away from its vent. As you know drain lines pitch down and the farther away from the trap you get the farther down your going..........you can only go so far before your below the bottom of the p-trap. If you go too far you have piped a form of an s-trap.

Hackney plumbing said:

Sizing does not determine if it's wet vented or not. If a fixtures vent receives the discharge from another fixture then its wet vented.

S trap is where the outlet of the trap(weir) extends below the bottom of the trap(j-bend) before it hits the vent. This is why pipe size has an effect on the distance the trap can be away from its vent. As you know drain lines pitch down and the farther away from the trap you get the farther down your going..........you can only go so far before your below the bottom of the p-trap. If you go too far you have piped a form of an s-trap.

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I think I got it, thanks. So does the pipe still need to be up sized in a wet vent if the distance between the fixture's trap and the weir is not enough to bring the weir below the bottom of the trap? I could move the vertical vent closer to the vanity if needs be.

A 1-1/2" trap arm can be up to 42" long.

Terry said:

A 1-1/2" trap arm can be up to 42" long.

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The arm would only end up about 24" from the vanity trap to the vent. OK wet vent with 1-1/2? Start the 1-1/2 with the trap?

This might clarify my other question:

Cut the whole fitting out and replace as much of the horizontal as you can in each direction and try to add a cleanout. When you get that combination cut out pipe in two combinations,one for the shower and tub and one for the toilet and lavatory. Proceed to run a new vent for the shower and tub.

By the way.....if thats Nibco Durapex I see in the background,you might have trouble with that pipe micro splitting. The redish orange pex is what I'm speaking of. Tho it could be Rehau.

Hackney plumbing said:

By the way.....if thats Nibco Durapex I see in the background,you might have trouble with that pipe micro splitting. The redish orange pex is what I'm speaking of. Tho it could be Rehau.

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Got interrupted here but yes, it is Nibco Durapex. That's mostly what the plumbing supply stores around here sell and what most plumbers use. I've never heard of it "micro splitting" or of much other problems with it (except i had a customer who had a rat chew thru his). I have very little pex at my house but I hope you're not going to tell me Durapex is a problem...

Hackney plumbing said:

Cut the whole fitting out and replace as much of the horizontal as you can in each direction and try to add a cleanout. When you get that combination cut out pipe in two combinations,one for the shower and tub and one for the toilet and lavatory. Proceed to run a new vent for the shower and tub.

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There is a cleanout. The iron goes under the exterior wall soon after the fitting I took a pic of and in the other direction it ties into the other bathroom. It'd be a lot of work just to remove a small percentage of iron.

A fernco will properly seal only to a straight, smooth, clean section of pipe.

Everything will be a lot easier after you cut that entire fitting out, as you can fit 2 PVC wyes in it's place.

The trap arm can be 1-1/2",
The vertical section would be 2-0"
The vent can be 1-1/2"

Helpful Plumbing Hints for Residential Construction by Bert Polk Plumbing Inspector Lincoln County

Terry said:

The trap arm can be 1-1/2",
The vertical section would be 2-0"
The vent can be 1-1/2"

Helpful Plumbing Hints for Residential Construction by Bert Polk Plumbing Inspector Lincoln County

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Working on this only when I don't have other work going so I'm just getting back to it. Thanks for the above link Terry, it's helpful. I was planning on going with a configuration similar to my pic in post #4 of this thread. I repeated the pic here. The changes I'll make are to add a vent to the shower line and change the double 2" wye to a single 2" wye (I don't know why I even thought I needed a double wye there). The lav will be vented above and drained separately below.

Is it right to have the tub/shower/lav drains entering the stack above the toilet drain? The link you provided shows an example with the toilet upstream but I'm not sure it matters.


Then I have another question...
I think I got ahead of myself on the shower drain. The second pic is of the shower floor area. I framed this out without realizing I'd need more room for the shower drain. Now I'm wondering if I have to take out some concrete to lower that drain. The pvc in the pic is just loose, resting on the concrete slab and is approx where the drain will be. The top of the medium 90 fitting is just about level with where the top of the ply subfloor will be.
How much space is nominal from the top of that 90 to the shower drain top? I'm guessing I need to take out some of that concrete...

Also, I was planning on putting the trap just outside the concrete wall which ends about where the yellow line is in the pic. Is there a problem with the trap placed 15" from the drain? Vent would come in after the trap.

Thanks, thanks, thanks!