Lavatory absolutely need a dry vent above?

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wwhitney

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Well the ones where I showed the short 45 is my attempt at showing the combo that I intend to roll up 45 degrees.
None of those need to be rolled up 45 degrees, and in fact where the upper shower trap arm joins the 3" drain can't be rolled up, it needs to be flat (2%). In that the total elevation drop from the shower trap to that 3" drain which is wet venting the shower is limited to 2" of drop (one pipe diameter).

So that connection, like the tub connection I first mentioned, should be a combo (aka wye plus 45) with both inlets at 2%. Definitely not a san-tee.

Cheers, Wayne
 
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None of those need to be rolled up 45 degrees, and in fact where the upper shower trap arm joins the 3" drain can't be rolled up, it needs to be flat (2%). In that the total elevation drop from the shower trap to that 3" drain which is wet venting the shower is limited to 2" of drop (one pipe diameter).

So that connection, like the tub connection I first mentioned, should be a combo (aka wye plus 45) with both inlets at 2%. Definitely not a san-tee.

Cheers, Wayne
Hmmm...seems I am misunderstanding something then. I thought this was how it should be when horizontal ties to horizontal...
1668207499210.png
 
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Nope. OK to do with WCs or a vented drain, not OK for a tub or shower being wet vented via that connection.

Cheers, Wayne
Thanks for your help on this. I added a question on the original post that no one seemed to see. I am curious what is the best way to proceed with this project. I have never done anything to this scale before. Is it best to start with the big pipe and work your way to the fixtures and vents or to start with the vents and fixture locations and work your way down?
 

Reach4

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Yes. It did not address a preference to start plumbing at the downstream or upstream part of the flows, and I should not have quoted what I quoted.
 

wwhitney

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Is it best to start with the big pipe and work your way to the fixtures and vents or to start with the vents and fixture locations and work your way down?
I've only done the DWV in two houses, so the pros might have a better answer for you. But in the layout in post #38, I assume the vent connection in the ceiling is existing, as is the 3" drain line at the right side of the drawing.

So I think what I would try would be to first do the drain work above the floor, stopping with the vertical risers that go through the floor. Leave those risers a bit long below the floor, and ideally with some vertical play, where they can't fall down lower than desired (adding extra slope to the above the floor horizontals) but you could push them up a bit.

Then below the floor I'd start at the existing 3" drain line and work upstream. With the drain risers poking through the floor, you have all your targets that you have to hit with the horizontal drain lines. And when you get to one of the risers, you can cut it to length and then make up the vertical joint by temporarily pushing up on the riser or pulling down on the horizontal.

That leaves the vents to do last.

Cheers, Wayne
 
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If you aren't interested in reading the why, just skip to the question at bottom, otherwise read slow, there is a lot of info here...

OK gents, I got this DWV about 90% done today (thanks for everyone's input). Everything above and below floor except the tub connection is done. I ran into a pretty big problem here. First off, I was using the manufacturers installation documentation to place my DWV pipe.
This image is what I went by...
1668463443504.png


I am guessing regular plumbers already know what I did wrong. I thought that circle was meant to be the drain pipe location. This was a huge mistake. I went through a lot of thought and trouble trimming off a joist tail (piece that went beyond the beam) and making room next to another joist to make this connection because I also have a beam running directly under this (hence why 2 joists overlapping beam from opposite sides), only to later figure out it was not the right spot. I assembled the tub drain set to get an idea of how deep my p-trap needed to be when I discovered my mistake. I am not sure why Delta dimensioned out the tubs drain location instead of the down tube from the overflow...I don't see how this is useful info to the installer.

Anyway, The correct location is now on the other side of the same joist (joist located right along the "A" dimension line in the above pic) and my p-trap is running parallel to and within a joist bay with that beam sitting right under it. I have to come out from above the beam, down out of the joist bay and then awkwardly bend over to where the 3" wye was installed (vertically oriented under the original hole). The only thing currently installed is the 3"wye and I can not move or rotate it without a sizeable amount of work and cost. I originally was going to do a 2" trap but it just will not fit in the bay above the beam and be low enough for the tub to connect so I am going to the store in the morning to get 1.5" fittings and trap.

I have figured out a way to make this connection and have correct slope and length of the trap arm. It obviously isn't ideal.
My question is, is there anything wrong with this image besides it being crude as hell (better software at the office for this stuff).

1668464505877.png
 

wwhitney

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Having some trouble reconciling the diagrams in your last post with the floor plan shown in post #38:

The 3" drain is wet venting the tub trap? Then as commented previous, the 3" wye has to be flat, with the p-trap outlet at the same elevation as the wye inlet. (flat, same elevation really means 2% slope).

Or, if there's a dry vent takeoff not shown in that 4" of trap arm between the p-trap and the "90 rotated 45", then there's nothing wrong with the drain configuration shown.

Cheers, Wayne
 
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Having some trouble reconciling the diagrams in your last post with the floor plan shown in post #38:

The 3" drain is wet venting the tub trap? Then as commented previous, the 3" wye has to be flat, with the p-trap outlet at the same elevation as the wye inlet. (flat, same elevation really means 2% slope).

Or, if there's a dry vent takeoff not shown in that 4" of trap arm between the p-trap and the "90 rotated 45", then there's nothing wrong with the drain configuration shown.

Cheers, Wayne
No, you are absolutely right. The posted picture in #38 is no longer accurate. As hard as I tried to plan that lower toilet before I laid the subfloor when it came to drilling the actual hole I was unable to achieve the shown location with the offset flange. So for the lower toilet, instead of going off to the right and then going up to connect to the other toilet run I had to go straight up from the toilet similar to post #21 (where I thought it would be in the first place) but without breaking off at 45 (the existing pipe to the right was a lot closer than I thought it was and also is 4"). I went straight up. This put it almost directly under the tub area and for some dumb reason, in the moment I completely didn't think about the wet vent when coming up with that new connection.

Damn, I am going to have to cut some stuff...sucks. It is tight up against that intersection of the two 3" lines.
 
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wwhitney

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OK, I didn't follow your descriptions of all the obstacles, but given that your p-trap is going to need to be lowered, note that the p-trap doesn't need to be directly below the tee of the tub waste and overflow. You could use a pair of 45s to offset the p-trap. In case that helps.

Cheers, Wayne
 
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Having some trouble reconciling the diagrams in your last post with the floor plan shown in post #38:

The 3" drain is wet venting the tub trap? Then as commented previous, the 3" wye has to be flat, with the p-trap outlet at the same elevation as the wye inlet. (flat, same elevation really means 2% slope).

Or, if there's a dry vent takeoff not shown in that 4" of trap arm between the p-trap and the "90 rotated 45", then there's nothing wrong with the drain configuration shown.

Cheers, Wayne
Actually, I think for me, the more sane way will be to try to add the vent. I think I see a way, but it will be complicated to get to where it needs to go. Instead of the "90 rotated 45" I will change it to a "santee rotated 45" (as I understand it 45 degree is considered vertical and thus the santee is the right fitting?) then continue that 45 angle through the floor, out from under the tub and into the bottom plate of the plumbing wall where I can hopefully turn it vertical, then up above flood rim of the sink and above the spout, shower valve and shower head, shift it over a stud bay, through top plate and across ceiling between joists to the existing vent above where the other two vents connect. Will be some work but I think better than cutting up the larger stuff underneath.

Thanks. Wayne...I know I ask a lot of questions but this is why lol.
 
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OK, I didn't follow your descriptions of all the obstacles, but given that your p-trap is going to need to be lowered, note that the p-trap doesn't need to be directly below the tee of the tub waste and overflow. You could use a pair of 45s to offset the p-trap. In case that helps.

Cheers, Wayne
Yeah I considered that, but there is no fixing the 3" wye without cutting it, and the two next to it out and redoing them all. I got three wye's back to back. I really do not want to take the chance of messing up all that alignment so, see the vent idea above.
 

wwhitney

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Instead of the "90 rotated 45" I will change it to a "santee rotated 45" (as I understand it 45 degree is considered vertical and thus the santee is the right fitting?) then continue that 45 angle through the floor, out from under the tub and into the bottom plate of the plumbing wall where I can hopefully turn it vertical
Yes, that works. To reiterate, the vent has to be vertical (at most 45 degrees from plumb) until an elevation of at least 6" above the flood rim. And any place where dry vents combine has to be at least 6" above all the flood rims of the fixtures served.

Cheers, Wayne
 
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