Options for adding a sink to our laundry room...bit of sticky situation

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goleary91

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Hello from Seattle,

We have a laundry room that only has a standpipe and a cleanout. We want to stack the washer/dryer and add a sink. To figure out what I was working with I opened up the wall. I was hoping I could move the standpipe to the right (just left of the 240v outlet) and then plumb the sink in on the left (where the standpipe currently is), but after opening up the wall I see some problems. First off, there are two vents to the right of the standpipe vent which means there isn't much room to work with to fit a standpipe + p-trap in the wall. Secondly, the standpipe drain runs through what appears to be a supporting post in the wall...I'd prefer not to have to drill another 2.5" hole in this post.

Option A: I was thinking maybe I could combine the two vents on the right into a single vent in order to open up some space, but I'm not sure if the right vent needs to be tied into the main vent stack above a certain height? And even doing that I think it still might be too tight to fit a p-trap in the wall with proper arm length to reach the vent...

Option B: Leave the laundry box/standpipe where it is, putting a double fixture wye where the current standpipe connects into the drain/vent (below the cleanout) and then run the sink drain outside the wall over to the left. Less ideal having the drain running outside the wall, but it will be out of sight behind the washer/dryer & cabinets that we plan to build.

Option C: Drill hole(s) in the post so that I can add the fixture to the left of the standpipe, but I think that would require multiple more holes in the post (one for the drain and another for the vent of the whichever fixture needs it). Are my concerns of drilling more holes in the post warranted?

Anyone have any other ideas?

1651344785477.png



Also I've read that a laundry standpipe p-trap needs to be 6-18" off the floor. Ours is certainly less than 6" off the floor, does that mean it was not built to code? Will this be a problem if I get the plumbing inspected for a residential permit to add the sink?


Thanks for reading and your advice!
 

wwhitney

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If that's a structural post, drilling a 2.5" hole through it was likely a serious error originally. In which case what is required is to open up the entire height of the wall and replace/repair the post. Then you bring all the necessary DWV out of the wall to the right of the post. If you have a stacked washer/dryer and a sink cabinet base, you can likely hide the out of wall DWV inside the sink base cabinet.

To determine if the post is structural, you either need to consult the original structural drawings, or open up the drywall enough to figure out the framing details and what the post is carrying.

Cheers, Wayne
 

Terry

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Maybe just go around the post and run pipe outside the wall for now.
You can add a sink off of washer standpipe. I could see the santee on the stack at a 45 with a street 45 into it, bringing it outside the wall. Then from the standpipe, an arm over to the sink, again outside the wall.
What you have now is a little tight to be making many changes.

index.php
 

goleary91

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Perhaps I am wrong about it being a structural post. This was put in when the house was constructed, there was no later modification for this laundry room.

Maybe just go around the post and run pipe outside the wall for now.
You can add a sink off of washer standpipe. I could see the santee on the stack at a 45 with a street 45 into it, bringing it outside the wall. Then from the standpipe, an arm over to the sink, again outside the wall.
What you have now is a little tight to be making many changes.

index.php
This looks ideal!

If I just add a santee to the standpipe and connect the laundry sink in like this:
1651351096483.png

Should I be good?
No additional vent needed?

Also, is it not a problem that the bottom of the standpipe p-trap is not 6" off the ground?

Thanks a ton!
 

wwhitney

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If it's a 4x4 post, then I would expect it to be structural. Definitely worth figuring out before you close it up--don't ignore the possibility.

Cheers, Wayne
 

goleary91

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If it's a 4x4 post, then I would expect it to be structural. Definitely worth figuring out before you close it up--don't ignore the possibility.

Cheers, Wayne
It is not. Upon closer inspection it looks like a 2x6 in the front, 2x8 on the left and 4xsomething behind it?
1651363699183.png

1651363821148.png

1651363749208.png


I realize this isn't conclusive, but I measured out where this "post" is upstairs and its the middle of the floor in my kitchen...no wall or post extending above it.

Would you still be concerned about it with all of this information?
 

goleary91

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Probably not then. Wayne
Gotcha, thanks!

Maybe just go around the post and run pipe outside the wall for now.
You can add a sink off of washer standpipe. I could see the santee on the stack at a 45 with a street 45 into it, bringing it outside the wall. Then from the standpipe, an arm over to the sink, again outside the wall.
What you have now is a little tight to be making many changes.

index.php
One more thing...

I'm a little confused about the suggestion to connect the laundry tray to the clothes washer standpipe. In the Seattle code I don't see any item 802.4.3.1. Also the Seattle code states that a washer standpipe length may not exceed 30":

804.1 Standpipe Receptors
No standpipe receptor for a clothes washer shall extend more than 30 inches (762 mm), or not less than 18 inches (457 mm) above its trap.

And yet IPC 2018 CODE: 802.4.3.1 states it must be no less than 30 inches.

I do plan on getting a permit/inspection for this work, but am confused about this not presenting in the Seattle Plumbing Code. Am I missing something?

Thanks for all of the your attention/responses!
 

Reach4

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Seattle uses UPC code-- not IPC code. Usually the UPC is less permissive.
 

goleary91

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For anyone that cares:

I went ahead and implemented the plan above even though Seattle code doesn't explicitly call out allowing the sharing of a p-trap between a washer and a sink.

IMG_3885.jpg


I just had it inspected and it passed inspection! Seems like things are to some extent at the discretion of the inspector, so I wouldn't take this to mean you definitely will pass inspection with this setup, but I'm happy to report that I did.

Thanks again to all in the thread that provided feedback.
 
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