Vent relocation, new drain install

[arod0422]

Hello all,

Long time lurker, first time poster.

Im doing a second floor bathroom remodel and i need to move a 2' vent line that was in a linen closet into the wall. It services a downstairs bathroom and laundry.

trouble is there is half a a joist right where i would need to drill. I will also be running a wye of this pipe to come down beside it and vent a sink i will be adding on that wall.

I'm building a raised floor wet room in half the bathroom so i will have some room to hide things if i have to come off the wall and above the subfloor horizontally for a small stretch before going vertical back below the subfloor.

any suggestions on what the best method here would be?

 

[wwhitney]

trouble is there is half a a joist right where i would need to drill.

What you mean by this is not clear. Could you mark up one of the photos (e.g. Microsoft Paint) with lines indicating the joist location? Below the subfloor shown, does the existing vent go straight down into a wall below?

Cheers, Wayne

 

[Sponsor]

 

[arod0422]

Hey wayne,

In the second photo you will see a pencil mark, that is a rough estimate of where the joist ends.

No, the existing vent 90's and then has a 2 1/2 foot run before it 90's again down a wall.

i will try and get some better pictures, but i have this one for reference.

thanks for your help!

 

[wwhitney]

In the second photo you will see a pencil mark, that is a rough estimate of where the joist ends.

You say joist, but your picture shows floor trusses. There's a big difference, with solid sawn joists you have some limited allowance to notch, while floor trusses can't be modified at all.

So if the pencil mark is the near edge of a floor truss (the truss is on the far side of the pencil mark), you have to avoid it completely. You can drill through the subfloor at a 45 degree angle to make a hole for the vent, the hole can almost kiss the truss without touching it, but I advise you to aim for a 1/4" to 1/2" gap to give yourself a margin of error. Then a diagonal section of vent goes through the hole, hitting a 45 in the floor system to go horizontal, and a 45 in the wall to go vertical. [You also mentioned wye'ing in another vent within the wall; if it's a dry vent for a fixture on this floor, the wye has to be at least 6" above the flood rim of that fixture.]

Cheers, Wayne

 

[arod0422]

Sorry about the terminology, yes it's a truss.

That was kind of my first thought since this is just a dry vent at this point. Thank you.

Yes I want to add a sink on this same wall, so I will have the same issue with the drain for it. Would the same method work for that? Except once it goes in the sub floor it will go horizontal till it ties in with the main drain. Something like this?

 

[wwhitney]

Yes I want to add a sink on this same wall, so I will have the same issue with the drain for it. Would the same method work for that?

Sure.

Cheers, Wayne

 

[arod0422]

Great! Im concerned about a cleanout. Im not sure where I could put it

 

[arod0422]

Good morning all,

Now that I have a plan for getting past the truss issue I need to determine the best way to tie into the main drain line.

Im changing most of the layout of the plumbing. I will be having a shower fixture on both sides of the bathroom so I'd like to have 2 drains. Tub pretty much stays where it was just centered.

Question is what would be the correct method to accomplish that, do
I use 2 combo wye's stacked one on top of the other? Or a double combo wye with 45's.

Sorry for the kindergarden art skills lol

 

[wwhitney]

So there's the question of venting these two showers and the tub. The simplest way to do that is use the properly dry vented lav drain to wet vent them. Which would work with your drawing if the drain going to the bottom left is the incoming lav drain.

Then what you need to do is combine the 3 fixtures with the lav drain one at a time. I will assume that your tub and shower traps are all 2", although the IPC allows 1-1/2". So then starting at the lav trap, your connectivity order and minimum sizing would be:

1-1/2" lav trap
1-1/2" dry vent take off, typically via a san-tee
1-1/2" wet vent with LT90 to go horizontal into the floor system (wet vent is carrying 1 DFU)
2" wye for first tub/shower
2" wet vent (wet vent is carrying 3 DFU, so may be 2")
3" wye for second tub/shower
3" wet vent (wet vent is carrying 5 DFU, so must be 3")
3" wye for third tub/shower
3" drain (or wet vent if further wet venting a downstream WC)

Do not use a double wye in the horizontal position; you can't control the pitch of the two branches independently like you can do with individual wyes. And when I say 3" wye, for example, I don't mean that it has to be 3x3x2, I'm just specifying the required minimum outlet size. So if the two inlets are 2" (the second wye in the list above), you could use a 3x2x2 wye (which doesn't exist as a fitting, so you could get a 3x3x2 wye and put a 3x2 bushing into the straight inlet).

Cheers, Wayne

 

[arod0422]

Hey wayne thank you for the detailed explanation! Im still alittle confused but it's clicking a bit more everytime I read it lol.


Yes that bottom one is the new lav drain I'll be adding, that will act as a wet vent. I forgot to draw it but I will actually have the same thing on the other side as I currently have a lav on that side that needs to tie in to the shower drain that will go on that side, and be a wet vent also.

Would that be to much venting?

Would I need to put 45's on the wye's to get the turns to each shower? Or should I cut the sub floor further back and start there so I have no turns?

And yes there is a WC down stream that has a vent i also need to find a way to get in the wall lol. The original solution will not work here as im installing floating vanity so I won't have anything to hide the pipe.

This is what the current setup looks like
For the rest of the plumbing that can't be seen

 

[wwhitney]

Yes that bottom one is the new lav drain I'll be adding, that will act as a wet vent.

Good.

I forgot to draw it but I will actually have the same thing on the other side as I currently have a lav on that side that needs to tie in to the shower drain that will go on that side, and be a wet vent also.

So if you have another lav that can act as a wet vent for some of the fixtures, then that gives you options on the connectivity order. What you are not allowed to do is wye together two unvented fixture drains. Each fixture drain either needs a dry vent before it joins another drain, or the first drain that it joins must be sized to be a wet vent (and one of the fixtures on that wet vent must have the requisite dry vent).

Would that be to much venting?

Not possible, you can always add an extra vent. [But two vents in the wrong places are not a substitute for one vent in the correct place.]

Would I need to put 45's on the wye's to get the turns to each shower? Or should I cut the sub floor further back and start there so I have no turns?

That depends on your layout. In the second image on post #8, if there is only one lav, which is connected at the bottom left, then that basic layout works, except per my post #9, if we call the 3 fixtures L, M, R, then first lav wyes in with L; then lav/L wyes in with M ; then lav/L/M wyes in with R. In other words the wye for R would need to be downstream of the wye for M; in the drawing it appears to be upstream, which would be combining two unvented fixture drains together, not allowed with wet venting.

Now if you have a second lav that isn't shown in that image, and if it wyes into M or R before M and R wye together, then the apparent order of connectivity of the fixtures in that image is OK.

And yes there is a WC down stream that has a vent i also need to find a way to get in the wall lol.

If there are no other fixtures that join before the WC joins, it would be allowed to wet vent that WC via the 3" drain carrying 1 or 2 lavs, 2 showers and a tub. If there are other fixtures, it would depend on what they are and how they are connected.

For more efficient future guidance, please provide a diagram of all of the DWV plumbing in the vicinity, showing all the fixtures.

Cheers, Wayne

 

[arod0422]

I should have started with the complete layout sorry. Here's some pictures. And a sketch. I swear I'm a better diyer than an artist.

 

[arod0422]

My plan is to keep the drain and vent that's upstream and use it to tie the second shower in.

 

[arod0422]

This is what I I'd like to ultimately end up with if it will work im just having trouble visualizing how the 2 drains would end up being simetrical. Or is that something I would work out with the ptraps?

 

[wwhitney]

This is what I I'd like to ultimately end up with if it will work

Yes, that's fine, if I mentally infer from what you've drawn something plausible in 3D. And definitely do use two different wyes on that branch down the middle the of the page.

im just having trouble visualizing how the 2 drains would end up being simetrical. Or is that something I would work out with the ptraps?

Not exactly sure what you mean. There is the question of whether everything will fit within the vertical space provided by the truss floor system. If you're tying into a 3" line that leaves the area, you can begin by thinking of the existing part that you are going to tie into as being at a fixed elevation. Then working from the bottom of your diagram upstream, everything rises as 1/4" per foot. [IPC would allow 1/8" per foot on the 3" drain lines, but I recommend avoiding that unless it would solve a problem for you that has no good way to solve.] And the main question will be whether the resulting shower p-trap elevations work out OK.

I expect it will probably be fine, but if you found that the drains would rise too high and interfere with the subfloor (or the shower p-trap would be too high, as the drain body sticks down below the subfloor) you'd have to look into replacing more of the existing 3" to get a lower starting elevation (starting in the sense of going upstream). Whereas if you find that the shower p-traps are too low and the bottom of the u-bend would hit the ceiling, you could adjust things higher (e.g. pitch your new work at 3/8").

Cheers, Wayne

 

[arod0422]

Thanks wayne! I really appreciate all your help.
I have a 100x better understanding of what I'm doing now based on all the info you provided.

I think i will be OK on space and I'm building a 4" platform to have the shower and tub "wet room" elevated.
would it be ok to go 2" on everything including the wye's on the 3".
Start at the
Bottom of my drawing with a 3-2 bushings like the builders did and do everything else in the 2"?

Also if I'm understanding now, since I have venting on both sides it doesn't matter which branch ties into the middle first?

The only other problem I have left to solve is that of the w/c venting. It was being vented by the sink I'm deleting.

 

[wwhitney]

Start at the
Bottom of my drawing with a 3-2 bushings like the builders did and do everything else in the 2"?

The IPC limits a 2" horizontal branch to 2 DFU. A lav is 1 DFU, a tub is 2 DFU, and a shower is 2 DFU. So exiting the wye where the
first shower/lav joins the tub, you have 5 DFU; existing the wye where the second shower/lav joins in, you have 8 DFU.

That means you must use 3" starting at that second shower/lav wye (you can build a 3x2x2 wye as discussed earlier). But if you use 3" starting at the first shower/lav wye, then your 3" branch could wet vent the downstream WC if the DWV configuration is correct. You left out that part of the DWV in your diagram.

Also if I'm understanding now, since I have venting on both sides it doesn't matter which branch ties into the middle first?

Yes.

Cheers, Wayne

 

[arod0422]

Ok i get it and it makes sense. I think this would be my final layout then.
If this works, my only question is how do I go about deleting the vent that is on the w/c line before the rest of the system ties in
( seen in my diagram on post 12)

cut and cap it right below the subfloor? (easiest)

Cut off the tee and add a new 3'' piece with couplings? (probably the correct way?)

 

[arod0422]

final layout

 

[wwhitney]

Yes and yes.

You're redoing some of the 3" anyway, so just demoing back to upstream of the dry vent takeoff gives the cleanest final result. But if removing the vent takeoff for the WC would be particularly difficult, I'm not aware of anything that would prohibit just capping the vent below the subfloor.

Cheers, Wayne