Venting Floor Drain (second floor)

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kjinxx2

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Hi there - I've been reading through your forums for some time now as I work on installing a second floor laundry room and I've run into a little issue where I can't seem to figure out the venting for my floor drain. My original plan was to vent the drain per the attached image (black is drain, blue is vent):

drawing.JPG

The issue is that my vent stack is offset from the drain stack - through some reading etc I've determined that I can't have a horizontal stretch of venting before I reach a minimum of 6" above the flood rim for the fixture. My solution was to move the sanitary tee directly underneath the vent stack and plumb back to the drain stack (modification in orange, removed washer drain line from drawing for clarity):
drawing2.JPG

The problem I'm facing is that I just don't have enough room for the fittings (if the sanitary tee is too high then my floor drain won't connect to the trap correctly, it needs ~5" of clearance) - the floor is framed in 2x12 lumber so I only have 11" of vertical space. Any help or ideas as to how I can properly vent this floor drain (it will be primed as well).

Thanks so much for your help!

Ken
 

wwhitney

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I've determined that I can't have a horizontal stretch of venting before I reach a minimum of 6" above the flood rim for the fixture.
Same thing applies to the washer standpipe, the "tie back to vent" should be at least 6" above the top of the standpipe.

New Jersey seems to be on the National Standard Plumbing Code, which I'm not familiar with. But you may be interested in section 12.6.2:

http://epubs.iapmo.org/NSPC/2018/mobile/index.html#p=193

That seems to allow your floor drain vent to go horizontal if necessary; one of the requirements is to provide a cleanout.

Another thing to note is that the plumbing codes define "vertical" as at least 45 degree above level. So you can stick a street 45 into the top of a san-tee and rise at that angle and not be "horizontal". Seems like that ought to fit in framing you've shown, since you've drawn the upper wall less than one joist depth offset from the lower wall.

Cheers, Wayne
 

wwhitney

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Another idea, if the street 45 in the top of the a normally oriented san-tee still doesn't fit, is to rotate the san-tee 45 degrees around the side inlet. So the top and bottom are both at 45 from the vertical. You'd want the side inlet to be in the direction coming out of (or into) the page in your drawing, which means using an elbow between the trap and the san-tee. Then you'd use a street 45 in the outlet of the san-tee to get back to true vertical.

Cheers, Wayne
 

kjinxx2

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I like that second idea with the san-tee rolled 45 degrees - that might be an optimal solution - posting a couple actual pics - this is my idea with the horizontal venting (I would have to add a cleanout to the vent, directly to the right of the washer clean out) - I think the 'horizontal vent' issue has been addressed for the standpipe as well - the vent slopes toward the drain and the drain slopes toward the drain stack:

0813201305.jpg 0813201306.jpg

I believe this meets the exception criteria listed in 12.6.2.1-3 after I add a cleanout - I might try the san-tee solution you offered, that may be cleaner


Thanks so much for your quick response!

Ken
 

wwhitney

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So of the pipes coming through the lower top plate, what's the one on the right with the elbow facing the camera?

I'm a little unclear from your photo which fittings are san-tees and which are combos. The the fitting downstream of the washer trap needs to be a san-tee, and the one for the vent take-off for the floor drain needs to be a combo.

What's your plan for keeping the floor drain trap from drying out? Not sure what the NSPC requires on that.

Cheers, Wayne
 

kjinxx2

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Hi Wayne -

The open pipe on the right of the lower top plate is a drain inlet for a slop sink - it will be vented through the wall to the right (out of picture)

-The fitting downstream of the washer trap is a san-tee (with cleanout above)
-The fitting downstream of the floor drain trap is also a san-tee - a combo is a long sweep wye, correct? Hmm, I definitely don't have room to fit a long sweep as the joist is directly in the way there - I will see if I can mess around with the configuration there

I plan on using an automatic primer valve (my floor drain has a primer inlet) that will prime the drain whenever the washing machine runs

Ken
 

wwhitney

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Possibly stupid question: why are you bringing all the drains down into the lower wall separately, instead of combining them in the floor joist bay?

Also, UPC allows an "emergency floor drain" to be part of a bathroom group, so if you call your slop sink a lavatory, you could wet vent the floor drain using the lavatory. That would be the easiest solution.

Cheers, Wayne
 

kjinxx2

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No stupid questions in my book! The reason I ran the drains down and combined in the lower wall instead of in the floor joist bay is because the fixtures are on 'both sides' of the drain stack - with the tight space between the joists I didn't have enough room to sweep the washer drain to the same direction to combine horizontally, and didn't have enough height to vertically combine them.

I have an idea that might work - I swapped the floor drain and the slop sink drain - that gives me room for a combo:
0813201346.jpg

I could also ditch the vent elbow, if that is not allowed, and use a short sweep (ignore the coupling I threw in there, I'll cut correct lengths when finalized)

So if I were to wet vent using the slop sink, I could just attach the floor drain to the horizontal run of the slop sink drain (using a wye?) and that would function as the vent for the floor drain? Gee that might be the way to go

Ken
 

wwhitney

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The problem with your latest photo is that the vent takeoff is supposed to be rolled up at least 45 degrees off horizontal. At least that is my understanding of 12.6.2.1. Now my statement that it needs to be a combo instead of a sanitary tee is based on the idea that it should be a drainage fitting because it's below the flood rim level of the fixture served. I would have expected that language in 12.6.2. If it's not somewhere else in the NSPC, then I guess you could use a sanitary tee.

Sticking with dry venting for the moment, have you considered venting the floor drain via the wall with the slop sink? That joist bay is pretty crowded right now.

For wet venting under the UPC, you use a 2"x2" san-tee on the sink with a 2" vent and you just join the floor drain trap arm to the horizontal sink drain.

Cheers, Wayne
 

kjinxx2

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Just want to thank you again for your helpful responses!

I think figure 12.6.2-A shows that it doesn't need to be 45 degree - just angled up so that the centerline of the vent is above the centerline of the drain.

I think the easiest way at this point would be to ditch the dedicated dry vent for the floor drain and wet vent it through the sink drain - I will have the trap arm from the sink enter into my wall and vent vertically via san-tee. Then the drain will travel to my drain stack, and my floor drain will connect via wye (see pic below, the sink drain is the bottom right most pipe) - I will remove the pipe that is covered by the cleanout. That will also open my joist bay up instead of being a spaghetti mess of pipes.

0813201408.jpg

I think this gives me plenty of room to install the floor drain and still allows all fixtures to drain and vent properly

Thoughts?

Ken
 

wwhitney

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I think figure 12.6.2-A shows that it doesn't need to be 45 degree - just angled up so that the centerline of the vent is above the centerline of the drain.
I mostly agree (the invert is the bottom of the pipe, so the bottom of the vent connection has to be above the centerline of the pipe), but that drawing shows a reducing takeoff. With a 2" combo, I think you'd have to roll it up almost 45 degrees. But you could use a 2x2x1-1/2" combo and then probably roll it up less.

I think this gives me plenty of room to install the floor drain and still allows all fixtures to drain and vent properly
The wye where the floor drain joins the sink drain has to be flat.

The distinction between a laundry sink and a lavatory is unclear to me, and if the person interpreting the code calls your slop sink a laundry sink instead of a lavatory, then it isn't allowed. But the IPC would allow it, so this is a point of contention. Certainly it will work.

Cheers, Wayne
 

kjinxx2

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Got it - thank you so much, you've offered more help than you can imagine!

Thanks again!

Ken
 
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