I Need to Vent

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Thomas K

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I will have to cut the dual lav drain right behind the wye in image 1877 and add a 2" long ell fitting to take it straight down through the floor plate. There's just enough room. Seems to join three 2" pipes on a single 2" pipe I will have to use (2) 2" wyes in addition to the 4 x 4 x 2 wye.

Yes, the shower was wet vented by that 2" drain coming from sink in smaller bathroom. I want to add a separate 1 1/2" vent for the shower, so shower trap can be a little higher. It was really dropped in original setup, and if I use a wet vent, it will still be dropped because drain piping has to be almost exactly same routing as before due to clearances between hallway walls and 2nd floor joists. That will mean adding a vent to that 2 x 4 load-bearing (?) wall that I'm not sure is a load-bearing wall.

Attached is a better photo of old shower drain. Drywall ceiling was attached to bottom of that 2 x 4" framing. I'm sure that whoever built that framing put it low to clear that shower trap, but it's lower than code-required minimum 7' ceiling. I will have to reframe, making it 2 1/2" higher to code compliant.

I'm not sure if plumbing a new shower would be IPC code-compliant if I just plumbed it with a wet vent the way it is now. I know a trap has to be lower than its vent, and the wye in attached photo is horizontal.


Almost forgot. The 4" long turn ell will work fine with upstream toilet flange.
 

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wwhitney

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Horizontal to vertical doesn't have to be a long turn 90, it can be a regular quarter bend (medium turn). [Same as the difference between a combo and a san-tee, in terms of radius of curvature.]

Wet venting the shower seems very efficient, but I see your point about the p-trap. Are those floor joists 9" tall? If so, and you want to do some drilling, you could tuck the lav and shower drains up into the joists. You'd need to drill some minimum 2-3/4" holes for the 2" pipe, and you could get up to 2-1/4" of fall (while keeping the holes out of the top and bottom 2" of the joists). So if it's under 9' from where the lav drain goes horizontal to the wye where the shower joins, that would work. Then after that wye you could jog down with a couple 45s and go just under the joists.

Cheers, Wayne

P.S. The lav drain only has to be 1-1/2", so if you ran 1-1/2" pipe to the shower, most of your holes would only have to be 2-1/4", and you'd be able to go an extra 1' or 2' (depending on whether the shower wye and the jog down can be in the same joist bay, or if for reasons of space, you'd need one 2-3/4" hole.
 

Thomas K

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I didn't consider drilling holes through the joists for the drains, Wayne. It's definitely less than 9' from where sink drains to where shower wye was. I'm not sure it would be worth the trouble, though, as the copper water lines are dropped beneath the joists.

I've attached some photos of the framing someone attached to the floor joists on lower level to hold drywall ceiling. I removed all of the drywall, some of which fell, to see what was above it. Wires and pipes. I don't think the wiring is supposed to be stapled to the bottom of the floor joists, either.
 

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Reach4

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Remember that when you glue pipe, it will go farther into the fitting than it does when you dry fit. You will need to cut longer pipes when you start gluing. Allow for that.
 

Thomas K

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Work I did this afternoon. Everything glued in place, nice slope. Speaking of slope, I could not get that 2" drain from twin vanity sinks (image 1879) to work. If I put a 45 degree fitting on bottom of pipe and add 2" wye, heel of wye hits that water pipe. And if I move water pipe. wye will be level with or slightly lower than 4 x 4 x 2 wye inlet, center of which is about 4" from bottom of joists. And I turned that 4 x 4 wye (img 1881) just enough from 9 o'clock position to have a slope. So I'm going to have to think about that one. I think I just got frustrated with it today.

Water pipe from 4 x 4 x 2 wye will have to run just below floor joists to have a slope, and I think I am definitely going to have to add a vent pipe to shower and drill holes for drain pipes through center of 2 x 10 joists, like Wayne suggested, to have enough height for downward slope toward main drain.
 

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wwhitney

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Looks good so far.

If you move the water pipe, is the joist bay wide enough for you to fit a long turn 90 in there with the outlet perpendicular to the joist and the hub almost against the bottom of the joist? The joist is doubled, so it'd be OK to shave a 1/2" x 1/2" bevel in the edge, for sure. If you can get a long turn 90 to fit, then you can use a downstream flat wye to join in the next drain (just above 9 o clock, like the 4x4x2 wye).

FWIW, the fitting above the floor, just after the wye, that elbow didn't need to be long turn. For horizontal to vertical a medium turn elbow is enough. And while it might be difficult now, you could use an elbow turned 22.5 degrees off vertical, with a (street) 22.5 to go vertical, to jog the vertical pipe away from the joist. Plus perhaps trim away the end of the sister on the right.

Cheers, Wayne
 

Thomas K

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First mistake I made, Wayne, as you can see in image 1879, is that I drilled the hole for the drain pipe too far toward water pipe. I wanted drain pipe to snug up to that piece of blocking support I installed. I don't really understand what you mean by using 22.5s to correct vertical drain spacing within joists, as pipe is pretty tight there. Piece of blocking is there because the original builders cut too much away from the vertical boards to pour cement and I put it there to support boards. I could remove it entirely, but there would be only about a quarter inch of subfloor sitting on joist and supporting floor plate.

That water line is 3/4", and I think it supplies water to the only working commode in house, there on first floor, so I can't just cut it and cap it for now. I will look tomorrow and make sure. But I'm also pretty sure that water line will have to be modified for drain pipe to work. I'm planning on removing some lines on first floor anyway, because they go to sinks that are no longer there. Not to get off subject, but wouldn't two of the Pex manifolds shown in attached photo work perfectly for the twin sink and shower valve supply lines? When I install water lines, I'll solder sweat adapters for the Pex.

If I understand you, you're advising me to run a drain line from a 90 degree long turn elbow to that new 4 x 4 x 2 wye and then install another 4 x 4 x 2 wye downstream of the one already there. Or did you mean install a flat horizontal wye between twin sink drain pipe and new 4 x 4 x 2 wye, with a branch 2" pipe jutting off toward the small bathroom shower and sink?
 

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wwhitney

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On the blocking, I was just suggesting removing the interfering 3" of length or so (which might in practice mean removing it entirely, then reinstalling new pieces after the drain is moved).

On the water lines, if you loosen up all the supports to the bottom of the joists, can you possibly drop all the water lines 2" to let the LT90 pass above them? If you want to make a temporary change (like cutting out the section in the way and jogging around the new DWV), Sharkbites are very convenient.

On the LT90 for the 2" dual lav drain, I was suggesting a flat 2" wye a little downstream wherever you have sufficient unobstructed room to bring in the shower/lav drain from the other bathroom.

Cheers, Wayne
 

Thomas K

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I can remove that blocking; may even add a 3/4" board for support, or a length of 2 x 4 right at subfloor. I'll also try to see if water lines will drop temporarily. If not, I will find a way to bypass.

I was curious about the flat wye. I know the wye at the 4" pipe had to be turned for slope, but I wasn't sure if an inline wye could be completely horizontal or not. From what I see in some plumbing articles, it can go completely horizontal. I will see what I can do with it tomorrow, dry fitting drain line and checking slope.
 

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Water pipe was cold supply for vanity sinks so I cut it and capped it temporarily with a Sharkbite. Photos show what I came up with after trying varying pieces of plumbing, but nothing is glued permanently yet. Good slope on wye and twin sink drain. Drain pipe for small bathroom sink and shower rests just below joists with bubble on level in farthest window. I didn't measure it exactly, but I'm pretty sure it's at least a 2 percent slope. I guess I need to cut a piece of 2" drain pipe and run it all the way over to where the small sink drain will join it and measure slope from that point to see if it's actually 1/4" drop per foot.
 

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wwhitney

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Looks good from here.

That arrangement you ended up with, with the 2" wye very close to the 4" x 2" wye, that was the situation for which I commented earlier you can avoid the middle 45 if you want. Basically put the 2" wye where the middle 45 is, where two of wye openings match the openings on the current 45 elbow. The third opening is then still at a 45 degree angle relative to the 4" line, so you do need one 45 for the 2" pipe farther from the 4" pipe.

Cheers, Wayne
 

Thomas K

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Looks good from here.

That arrangement you ended up with, with the 2" wye very close to the 4" x 2" wye, that was the situation for which I commented earlier you can avoid the middle 45 if you want. Basically put the 2" wye where the middle 45 is, where two of wye openings match the openings on the current 45 elbow. The third opening is then still at a 45 degree angle relative to the 4" line, so you do need one 45 for the 2" pipe farther from the 4" pipe.

Cheers, Wayne

I think you mean rotating that 2" wye 180 degrees, and attaching the drain pipe from the vanity sink drain long elbow to wye the same way it is now (only 180 degrees out.) Second pipe (to shower drain) will extend out a few feet from wye and then turn back toward shower drain with one 45 degree fitting. If I am understanding you correctly, this will work if I can get the wye and twin sink drain pipe to line up.
 

Thomas K

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See my earlier ASCII art here:

https://terrylove.com/forums/index.php?threads/i-need-to-vent.90139/page-13#post-655125

Starting with the configuration of the 2" wye shown in your picture, I would describe it as "rotate the wye 45 degrees CW as seen from above; then rotate 180 degrees around the center line of the straight path of the wye."

Cheers, Wayne
Heh, I think I missed a step, Wayne. I meant to say install the 2" wye onto pipe jutting from 4 x 4 x 2 wye or flush with said 4" wye first. Then rotate it 180 degrees. Or I'm not understanding the required turns.
 

Thomas K

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Got it. I thought this is what you meant, but wasn't sure. I will rearrange fittings tomorrow and post photos before gluing.

That will actually move drain pipe closer to shower and other sink, if I attach twin sink drain to first pipe parallel to 4" pipe. Or did you mean attach twin sink drain to outermost pipe?

Are you sure you're not an engineer?
 
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wwhitney

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Well, use your current configuration if it has features that are desirable. Or use my proposal if you prefer its features. If you really want the parallel drains close together, use (2) street 2" wyes. Or if you want to move the more upstream 2" wye farther upstream (closer to the 2" long turn 90 with the double lavs), stick with your configuration.

Cheers, Wayne
 

Thomas K

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The only reason I wanted pipes so close together was to try to put ceiling really close to joists, which will be impractical. So pipes can be staggered as your schematic suggests. I did some remeasuring, and, except for area where drain pipe is, I can install ceiling framing that will raise ceiling from its former 7' height to 7' 8" as in the adjoining room.
 
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