Will this vent layout work? Can I use 1-1/4" for vents?

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Jthurm

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I'm working on a remodel and need some advice on venting two sinks and a washer. Location is Kentucky.

I would like to avoid adding any additional venting to the roof and I'm hoping to be able to tie into an existing 3" stack. The biggest hurdle would be turning around two corners, but I think I can make it work. Would the layout in the attached photo work if I slope the vent lines 1/4" per foot? A few notes/questions about the photo:

1) I would use a 3" x 3" x 1-1/2" x 1-1/2" Hub PVC Double Sanitary Tee. I think the one in the photo is upside down. I will rotate it 180 degrees so the flow is correct.

2) Is running 1-1/4" vent lines acceptable or would they need to be 1-1/2"? I would change the sanitary tee on the washer vent to transition to 1-1/2" or 1-1/4". I would prefer to run 1-1/4" vent lines because it would be easier to run around the pex lines used for the shower next to the washer box.

3) I plan to reroute the switch box to accommodate the vents.

4) The distance between the washer box and the trap is a little over 24". As you can see, I'll need to offset the drain to reach the trap. From my understanding, the washer drain needs to be 18" minimum. Is that 18" measurement the straight pipe at the washer box or the total length of the drain including the 45's, which would be around 24"?

5) This is a single-story room and there is no attic space above this room.

Thanks in advance for the help and advice!

venting copy.jpg
 

wwhitney

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Kentucky has its own plumbing code, so to get accurate answers you're going to have to check it yourself, or wait for a Kentucky plumber to respond:


1) It doesn't matter, but people do like them upside down for vents.

2) See the opening sentence above. The IPC would allow a 1-1/4" branch vent for any branch drain up to 2". So for the IPC (not Kentucky), it would be fine, although 1-1/2" is far more common, I believe.

4) Have you considered getting a different box that would let the top of the standpipe be far enough to the right to avoid the offset? I would expect the 18" minimum (or whatever your code has) to apply to the vertical distance.

Cheers, Wayne
 

Jthurm

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Kentucky has its own plumbing code, so to get accurate answers you're going to have to check it yourself, or wait for a Kentucky plumber to respond:


1) It doesn't matter, but people do like them upside down for vents.

2) See the opening sentence above. The IPC would allow a 1-1/4" branch vent for any branch drain up to 2". So for the IPC (not Kentucky), it would be fine, although 1-1/2" is far more common, I believe.

4) Have you considered getting a different box that would let the top of the standpipe be far enough to the right to avoid the offset? I would expect the 18" minimum (or whatever your code has) to apply to the vertical distance.

Cheers, Wayne
Thanks for responding, Wayne.

I could reconfigure the washer box to put the drain on the right side, but my concern is the pex lines being squeezed in front of the 2" pipe. It just seemed wrong to try to shove the pex lines there. Is that common practice? Having the offset drain provided a clear path for the pex lines to run to the valves.
 

wwhitney

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I could reconfigure the washer box to put the drain on the right side, but my concern is the pex lines being squeezed in front of the 2" pipe. It just seemed wrong to try to shove the pex lines there. Is that common practice?
Couldn't say what common practice is, as I don't have sufficient practice.

2.375" (2" PVC OD) + 0.625" (1/2" PEX OD) = 3", meaning you'd only have 1/2" clearance for a 2x4 wall, shared between the PVC/PEX clearance and the clearances to the drywall/sheathing. So I see your concern.

I guess you have to pick the least wrong option: the offset in the DWV you have, passing the PEX over the DWV, or looping the PEX around the whole box.

I guess if you push the trap against the stud on the on left, and the box against the stud on the right, things still don't line up?

Cheers, Wayne
 

Jthurm

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Couldn't say what common practice is, as I don't have sufficient practice.

2.375" (2" PVC OD) + 0.625" (1/2" PEX OD) = 3", meaning you'd only have 1/2" clearance for a 2x4 wall, shared between the PVC/PEX clearance and the clearances to the drywall/sheathing. So I see your concern.

I guess you have to pick the least wrong option: the offset in the DWV you have, passing the PEX over the DWV, or looping the PEX around the whole box.

I guess if you push the trap against the stud on the on left, and the box against the stud on the right, things still don't line up?

Cheers, Wayne
I can move the trap about 1.5-2" closer to the stud on the left, but I would still be in the same boat with the offset. The box was originally in the stub bay to the left, but that's where I had the issue with stuffing the pex lines in front of the 2" pipe, so I moved it over one bay.

I know the offset drain is acceptable, but may not be ideal. I just don't know what restrictions there may be on the lengths before and after the 45's.
 

wwhitney

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I know the offset drain is acceptable, but may not be ideal. I just don't know what restrictions there may be on the lengths before and after the 45's.
Very likely none, most likely the limit would be on the height difference of the top of the standpipe and the trap. But you'll have to check the Kentucky plumbing code to be sure that's true in your case.

Cheers, Wayne
 

Jthurm

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I forgot to mention that the wall with the washer is an exterior wall, which is one of the reasons I prefer to use 1-1/4" PVC (smaller holes). Are there any issues with drilling through two exterior studs like that? My only other option would be to vent through the roof, but are there any potential issues with drilling through the top plate of an exterior wall?
 

Reach4

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Does replying "bump" this to keep it active for folks?
What more is there to say? Are you wondering more about function, or whether something will meet Kentucky plumbing code? What you propose looks like it should function well, but I don't know that anybody here has studied KY plumbing code. There is a good chance that what you propose would meet KY code, but we don't know.

In most codes, you don't need to separately vent toilets, as long as a 2 inch pipe from the vented lavatory joins the toilet waste before that waste joins non-bathroom waste.
 

Tuttles Revenge

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Kentucky has its own plumbing code, so to get accurate answers you're going to have to check it yourself, or wait for a Kentucky plumber to respond:


1) It doesn't matter, but people do like them upside down for vents.

2) See the opening sentence above. The IPC would allow a 1-1/4" branch vent for any branch drain up to 2". So for the IPC (not Kentucky), it would be fine, although 1-1/2" is far more common, I believe.

4) Have you considered getting a different box that would let the top of the standpipe be far enough to the right to avoid the offset? I would expect the 18" minimum (or whatever your code has) to apply to the vertical distance.

Cheers, Wayne
That is a Painful read through what they call a plumbing code.. Found waste sizing but no vent sizing pg 65,67. They seem to just lump a bunch of unrelated stuff in whatever order. Good luck.

OH.. Finally found something on vents.
Looks like 1.25" vents can travel up to 30ft but are limited to 2 fixture units(pg 72). A automatic clothes washer is considered 2 fixture units (p65).
 

Jthurm

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That is a Painful read through what they call a plumbing code.. Found waste sizing but no vent sizing pg 65,67. They seem to just lump a bunch of unrelated stuff in whatever order. Good luck.

OH.. Finally found something on vents.
Looks like 1.25" vents can travel up to 30ft but are limited to 2 fixture units(pg 72). A automatic clothes washer is considered 2 fixture units (p65).
Thanks for responding! I agree about it begin a painful read. I tried to skim through it to find what I was looking for, but it was difficult.

I read page 72 as the number of fixtures (2 sink drains, for example). The way I take it is 1-1/4" pipe can run up to 30 feet and vent two fixtures.

I read page 65 as the actual drain line where it refers to fixture, but I honestly have no clue. That section relates to waste, soil, and traps, but it doesn't say vent. So, I'm not entirely sure how to interpret that.

If I'm understanding it correctly, I think my plan would work since both runs to the 3" stack would be less than 30ft. I think I need to grab some more 2x4's to double up the framing since I'll be boring and possibly notching some of these.
 
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