Add Washing Machine and Utility Sink to Basement

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zanman

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Hi All, first time poster here. Hoping to get some feedback on the best way to drain a washing machine and laundry sink i am adding in the basement of a late-70's home. I have been reading forums all day, but haven't quite been able to find a direct answer to my problem.
I believe this user has a very similar situation

I have the option of draining either to the 3" main that services the upstairs (2x full bathrooms), or a 2" that just services the kitchen sink+dishwasher (see photos below). Venting is obviously the challenge as both lines service multiple fixtures upstream, and venting to the attic would require opening walls on the main floor at a minimum.
Option 1: Plan would be to put washer/sink next to water heater, run 2" pipe behind water heater (there is space)
Option 2: Ignore drywall, basement was previously finished but I am demo'ing right now.

I believe this is a good example of how to "properly" handle this situation, the only difference is that in my case, the "vent" in the top-right-corner would be actual be an existing drain line.

My Questions are:
1. Which route do you think is the best to use (option 1 or 2). Would it be advantageous to send the washer to one and the sink to the other? (they are both located fairly close to where the washer/dryer need to go).
2. Is it possible that I may not need to vent? I have heard of 'wet venting', but done have a good understanding of when you can/can't get away with it. In this case, all upstream fixtures are properly vented to the roof.
3. If not, what would you recommend as an alternative? I've created a crude schematic of how this might be done using an AAV. Please critique, your feedback is appreciated.
 

Stuff

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Easier to tap a 2" pipe than a 3" one. And less intrusive to the rest of the family.
You always need to vent. Wet is venting not allowed between floors. Some places don't allow AAVs so check your local codes.
Do you really need both a standpipe and a tub? Dumping the washer into the tub isn't as pretty but less problematic.
 

zanman

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Easier to tap a 2" pipe than a 3" one. And less intrusive to the rest of the family.
You always need to vent. Wet is venting not allowed between floors. Some places don't allow AAVs so check your local codes.
Do you really need both a standpipe and a tub? Dumping the washer into the tub isn't as pretty but less problematic.

Hey thanks for the reply. I would prefer to use the 2" connection as well.
My city appears to adopt IPC 2012 with no amendments, so I don't see an issue with an AAV. As for dumping the washer into the sink, i don't think this would be a problem necessarily, but if i'm going to go through all this trouble i figured i may as well just add separate p-trap and standpipe for the washer.

Would I need to have a separate AAV for each fixture, or is it sufficient to vent both the sink and the washer with a single AAV provided they are located within a certain distance? (Like my diagram shows). Also is there any issue with having both fixtures share a 2" horizontal?

Thanks, and Merry Christmas!
 

Reach4

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Would I need to have a separate AAV for each fixture, or is it sufficient to vent both the sink and the washer with a single AAV provided they are located within a certain distance?
I think you need venting on each trap arm before the waste joins. I am not a plumber. Two AAVs would be simple.

To use one AAV, you could put the AAV above a 2 inch double fixture fitting between the sink and standpipe, run the trap arms into the side ports, and have the AAV above. Long sweep below.
1216rj_crackingthecode_img2.jpg


You could also run two vent lines up to 6 or more inches above the higher of the flood levels of the sink and standpipe, then run horizontally to join the vents to a pipe with a shared AAV.
 
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Stuff

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I'm not a plumber either but wouldn't want to combine a laundry standpipe with anything that wasn't vented first. Too high a chance it will suck the sink's trap dry. What about something similar to below? Key is stacked san-t's. Before proceeding wait to hear what the real plumbers recommend.

sink_LI_zpsgg2dkibh.jpg
 

Jadnashua

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Run two vent lines up to at least 42" above the floor, one from each trap arm, then you can combine them to use one AAV.

washer_rough_b.jpg


Plumbing codes require that both the laundry tray and the washer have their own vents.
Wet venting is only allowed for "bathroom" groups. The laundry is not a bathroom group.
Terry Love
 
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zanman

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Lots of great ideas, thanks everyone. Now that you mention it it does make sense that each trap needs to be vented in some capacity. I really like the idea of just stacking "san-t's" and sharing the AAV. Thanks for the diagrams @Stuff and @Reach4 !

Do you guys have an recommendations on securing the pipes? I was going to just find some pipe clamps and screw/nail them into the concrete walls with some masonry fasteners?

Lastly, are there any special "tricks" for slipping fittings into existing lines like this? The only way I've been able to do it in the past is by "pulling" the cut pipe apart and praying there is enough space to slip in the fitting before the cement dries. In this case however, i'm not sure that will be possible as the pipe is secured by the floor slab below, and the kitchen sink assembly upstairs. Is there a better way to do this, or are you pretty much stuck using those rubber repair-clamps (like below)? Thanks

mission_bandseal.jpg
 
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Cacher_Chick

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In an unfinished space, I mount uni-strut to the concrete or paint some pieces of 1x6 or 1x4 and mount those to the concrete as stand-offs to mount the piping to while keeping it off the concrete.

The rubber coupling you posted is not correct. At a minimum, use a shielded coupling which will maintain the alignment of the piping system.
2ZJ87_AS01
 

Reach4

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You will need one or two shielded couplers, depending whether the last-gap-filling pipe can be displaced to the side as you glue it on. So you may be able to glue one end and use the coupler on the other end.

The coupler will be pushed on and out of the way while the cut ends are brought together. Then the coupler gets slid.

Dish-washing detergent is a good lube to make sliding a little easier.
 

Jadnashua

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If you loosen the screws on the sleeve, you can slide it off of the rubber component. Slide that metal part onto the pipe. Place the rubber on one end up to the stop in the middle, then roll the other half of the rubber back upon itself. Place the other part you want to clamp it to, roll the rubber back onto it, slide the sleeve in place and tighten the clamps and you're done.
 

zanman

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Update: Everything is installed and works great! Here are some photos of the progress and final result, let me know what looks good and what could be improved for next time:
https://photos.app.goo.gl/T69EHG5jxSiUgoww6
Thanks to everyone for the tips and advice, I really appreciated the diagrams and explanations.
I did end up having a few small hiccups, after gluing the ABS together i must have jostled the existing 2" stack too much because it started leaking at the fitting above (just under the kitchen sink). Thankfully I was able to chisel out and re-glue the fitting and not have to open up the wall behind the sink upstairs. So far no more leaks.

P.S. The forum doesn't seem to like my embedded images from Google Photos. Idk if there is a better way to do this. Worst case the link above should work.
 

Reach4

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Zanman, looks good. New link works.

My main concern would be the dryer vent clogging.

The new standpipe is long under the maximum of UPC (30) and is fine under IPC (42 max) (which may be what your KC plumbing code is or resembles).
 

zanman

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Zanman, looks good. New link works.

My main concern would be the dryer vent clogging.

The new standpipe is long under the maximum of UPC (30) and is fine under IPC (42 max) (which may be what your KC plumbing code is or resembles).
Dryer vent is ~10ft of 4" pipe which is still well under the 28' maximum listed for 4-elbows in the dryer installation manual. Although I admit I did not look this up until just now :)

I wasnt sure what to do with the standpipe considering my homemade "pedestal" gives the washer an 18" boost, so i purposely left it at the max (somewhere around 42" from floor) i figured it can always be cut shorter if needed.
 

Reach4

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After further review... I think having the laundry sink connect into the vent line for the standpipe is not technically allowed. I am not a plumber.

If the top of that standpipe is only 42 inches above the floor, I mis-estimated your standpipe height.
 

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Cacher_Chick

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The vertical wet vent is allowed here where I live, but in other places it is not. Functionally, I have never known it to cause a problem.

If I had to use an AAV, I would mount it higher than the flood rim of the standpipe, that way if the piping ever backs up, it would not contaminate the diaphram in the AAV.
 
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