# Washer and sink -> one drain, one vent



## Alan (Apr 12, 2006)

Just FYI, since you don't have it sized, the washing machine should drain into a 2" line.

None of those options would be legal here where I live.


Keep your main drain low in the wall. Wye/combo up for your sink, vent up, continue down for the washer, and either flat vent it or Long sweep up and then vent up tie into sink vent and tie back into vent stack.

If you put your drain line at about 10" you should be low enough to combo up for the utility sink and high enough to flat vent the washing machine. Buy fittings and check before you go drilling


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## DannyT (Mar 23, 2011)

option 1 would work as long as the distance from the p-trap to the vent is within 5 feet. I used to do them this way in western ny all the time and was legal there as long as the vent was 2 inch. if its farther then 5 feet just put a tee on its back and tie back into the existing vent


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## Alan (Apr 12, 2006)

DannyT said:


> option 1 would work as long as the distance from the p-trap to the vent is within 5 feet. I used to do them this way in western ny all the time and was legal there as long as the vent was 2 inch. if its farther then 5 feet just put a tee on its back and tie back into the existing vent


:no::no::no:

That would have the sink dumping into the washing machine's vent, which is OK as long as you up-size the piping below the sink to 3".

P.S. You can ACTUALLY dump a washing machine discharge into a utility sink, but I never really liked that option. I wouldn't do it if I were you, since you have another option available.


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## Ishmael (Apr 24, 2007)

Of course it all depends on your local code. Here in MA, only "Idea #1" would be correct *IF*:

1) (*Assuming both horizontal waste arms are 1 1/2" ID*): 

2) The vertical waste is a minimum or 2" (up to the height of the upper horizontal waste arm). The vent above that tee can be as small as 
1-1/4" (but typically 1 1/2")

3) The distance between the two tees is a maximum of 10" (center to center)

4) The maximum length between the trap and vent is 5 feet for each waste arm (minimum is 2 pipe diameters, or 3" in this case). They can be "re-vented" if you have to run them longer than 5' from the vent (i.e. - take another vent riser off the horizontal waste arm and tie it back into the vent stack).

5) No 90 degree bends on the vent until it is a minimum of 6" above the flood level rim of the highest fixture served (most likely the washing machine standpipe - which must be a minimum of 18" long measuring from the inlet side of the trap to the top of the standpipe).

This piping arrangement, BTW, is called a "miscellaneous common vent".

*EDITED TO ADD: *If the vertical waste into which you're tying the two waste arms is also serving as the vent for the toilet (a "wet vent"), it may not be permissible to dump the washing machine into it (it isn't in MA - you can't wet vent with a laundry waste). It may be allowed in your neck of the woods, but check into it. Also, if it is intended as a wet vent for the toilet, then the vent must also be 2" ID - cannot be reduced in size.


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## cmyk (Mar 3, 2011)

Just to clarify, the vent pipe diameter currently is 2" ID above the current horizontal arm and 2 1/4" ID below the arm into the main drain.

The arm for the laundry stack would be a maximum of 4 feet in length and the sink would be about 3 feet, they're on opposite sides of a wall, but the plumbing will be in that order and less than the required 5 feet. The vanity sink is for the bathroom, the laundry will be on the other side of the same wall.

Ishmael, I'll have to check into the vertical waste/toilet vent issue. The toilet waste pipe sits between the two vents away from the wall, so it could be attached somewhere in the middle to the main drain and could be using either the main vent or the secondary vent as a vent.


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## cmyk (Mar 3, 2011)

Here's a revised diagram with some pipe sizes, existing and proposed. I'm still not sure about the toilet waste/vent pipe and where it hits the main drain. Could the size of the left vent pipe, in that it's larger at the bottom than the right vent be any indication of this? The MAIN vent is elsewhere in the house.

How does this look?


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## Ishmael (Apr 24, 2007)

You're throwing me off with the "2 1/4" ID". Is this PVC pipe? ID = internal diameter. 1 1/2" ID PVC has an OD (outside diameter) of about 2", and 2" ID PVC has an OD of roughly 2 3/8". Standard sizes of cast iron and ABS are basically the same as PVC (give or take a 1/16" or so). DWV comes in some other sizes, but not 2 1/4".

The fact that it's larger than the other vent pipe (which presumably serves only the shower) does seem to indicate that it's intended as a wet vent serving the toilet and the sink. As I said, here you wouldn't be allowed to use that as a waste for the laundry. And, as a wet vent, it has to be a minimum 2" ID all the way up to where the ent ties into the main vent stack and/or exits through the roof.


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## cmyk (Mar 3, 2011)

Sorry for the confusion, I thought ID was short for in diameter - lol! Those are all approx. outside diameters, so then the 2" diameters are actually 1 1/2" ID like you said, and that 2 1/2" OD pipe is 2" ID.


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## cmyk (Mar 3, 2011)

Since the builder, (which is a larger home builder in the area, not an amateur, so they would also be using professional contractors) roughed in the plumbing for this, wouldn't they have roughed in the wet vent for the sink and toilet to code? They roughed it in with the assumption that it would be a bathroom with a sink, not just a toilet and shower and that little horizontal arm coming out of the left vent pipe seems to indicate this as well... Maybe this is to code here in Ontario? I'm hoping so at least. 

So if this setup isn't possible, is Alan's suggestion the way around this? Or is this vent setup as it is, simply not going to work unless I were to tie the washer stack into the main house vent?


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## Ishmael (Apr 24, 2007)

I never assume that the guy before me did everything properly:laughing:. But if the whole piping arrangement was meant to wet vent the toilet and sink together, then the only issue (for me) is the 1 1/2" vent above the existing (currently capped) waste arm. My local code dictates that should be 2" minimum.

The only other question you need to find an answer to is whether or not you're allowed to dump a laundry waste into a wet vent in your neck of the woods. Is there another laundry connection somewhere else in the house, or was the laundry always intended to be in this location?

If there's a laundry connection somewhere else, then I'm guessing the original plumber set it up for just the sink and the toilet.

Alan's suggestion would work, but it wouldn't change the fact that your laundry is draining into a wet vent. If the question is "will it work?", Then the answer is yes. If the question is, "is it proper/will it meet code?", then you've got some research to do.


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## cmyk (Mar 3, 2011)

Thanks Ishmael. There is a laundry upstairs on the main floor but we wanted to move it to the basement, so I believe the main floor laundry is venting to the main vent. It makes more sense that this basement rough in was only intended for a bathroom versus adding a laundry, but I'll check the code on this, and I might just call a plumber to see what he thinks since he'll more than likely know the local code off by heart instead of me digging through lots of pages of code to find the answer. 

Thanks for your assistance!!


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## Alan (Apr 12, 2006)

Ishmael said:


> Alan's suggestion would work, but it wouldn't change the fact that your laundry is draining into a wet vent. If the question is "will it work?", Then the answer is yes. If the question is, "is it proper/will it meet code?", then you've got some research to do.


Actually by my local code it wouldn't now that you mention it. No telling whats under that portland cement, but if it is indeed a wet vent we require the "wet vented section" to be one pipe size larger than the required minimum if it were to be a drain.

:thumbup:

Will it work? Heck yes. If you lived out in the sticks would I do it? I donno about that, but you sure as heck could do it yerse'f! ! ! ! ! :wink:


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## cmyk (Mar 3, 2011)

I checked with a local plumber and he said that the code here is based on max fixture units depending on the size of the pipe. A 2" ID pipe can hold 5 fixture units. He didn't see too much of a problem with the laundry stack draining into the lavatory vent simply due to the size of the pipe. There might be some issues if the laundry were draining and the toilet flushing at the same time, but the size of the pipe should adequately compensate, and how often would that occur anyways (he said).

As far as venting the laundry in conjunction with having a sink vented, he suggested this type of setup, which I found on another site:









So the laundry vent will tie back in to the secondary vent higher up, and the sink will drain and vent directly into the secondary vent/drain.


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