Revised Laundry Drain

[Mr.T]

I’m in Michigan and my city adheres to the 2015 IPC code.

Next item on the list of things to repair are some large notches/holes run through an exterior load bearing wall from an original copper drain that was in place. (see pic).

This is a laundry room and I am putting all new drains for a laundry tub on left and washer standpipe on the right.

My intent was to set it up as follows (see dry fit pic):
- Offset the drain out of the load bearing wall using two short 90’s
- 2” double fixture fitting
- Clean-out directly above the double fixture
- 2” vent straight out the roof.

My main concern is the short sweep 90’s. Any issue here? I’m trying to keep the drain trap low to support a deep laundry tub so that’s driving the short 90’s. Anything else I’m not considering?

Thanks to the continual support from this group!

 

[wwhitney]

The quarter bend is not allowed for the vertical to horizontal transition below the double fixture fitting, that one needs to be a LT90. The horizontal to vertical can be a quarter bend.

The IPC requires a laundry standpipe drain to enlarge to 3" when it joins another fixture. So you would need to upsize the drain coming up from below the floor to 3", and use a 3" double fixture fitting. Or you could use stacked san-tees, which would let you put the lower 3x2x2 san-tee for the laundry tub with the barrel (straight path) at 45 degrees off plumb to get it lower. The order from the floor up would be (some fittings possibly street): 3" vertical drain, 3" 45, 3x2x2 san-tee with side inlet horizontal for laundry tub, 2" 45, 2" san-tee for washer standpipe.

If you want to avoid 3" through the floor, your only 2015 IPC option is to discharge the washing machine into the laundry tub. For the 2018 IPC, you could use a single trap for both the standpipe and the laundry tub, see 802.4.3.1 (there's also a nice diagram, not sure why it's not on the link below, but a web image search on the code section should bring it up).

https://up.codes/viewer/kansas/ipc-2018/chapter/8/indirect-special-waste#802.4.3.1

Cheers, Wayne

 

[Sponsor]

 

[Mr.T]

Wayne,
As before, thank you for the help and fast reply!

The long sweep is what I was worried was needed. I could make that work, I would just need to move the one stud on the left. So not a big deal at all. But it really doesn’t matter based on your other comment.

No way I’m upsizing to 3”. I’ll talk to inspector and see if there is any special allowance for a double fixture fitting for this config. Seems like inspectors should make an exception given how functional and commonplace this setup would be for laundry rooms.

If not, then I’ll investigate the alternative of tiring in to the washer discharge trap arm. I found the image you spoke of and I could find a way to make that work. Thanks again and stay tuned…

 

[Mr.T]

Wayne,
Assuming this is the configuration you were speaking of (pic and description attached). I noticed one concerning thing about this set up. If all of this is behind a finished wall, down the road, won’t it seem odd to look under the laundry tub and NOT see a traditional Ptrap?

I get that anyone poking around should understand the local code, but it does seems like most people with traditional knowledge of plumbing might think there is a missing Ptrap. Thoughts?

 

[Jeff H Young]

Didn't see any mention of 802.4.3.1 sizing of standpipe or trap so if that code is in 2015 guess you are good ( Wayne posted 2018) inspectors can let that go or not but they are supposed to hold you accountable to the code adopted .