# washing machine P trap and drain



## hammerlane (Oct 6, 2011)

john_bry said:


> Does the drain/standpipe for a washing machine need a p trap?


Do you want sewer gases in the location of this standpipe?


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## john_bry (Sep 17, 2012)

*washing machine wet vented to utility sink vent line*

Can the washing machine drain line be wet vented to the utility sink vent?
My utility sink has a dedicated 2" vent.

Thx!


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## hammerlane (Oct 6, 2011)

john_bry said:


> Can the washing machine drain line be wet vented to the utility sink vent?


Provide a diagram of what you are proposing to do. Wet vented fixtures (toilet, bathtub, shower, or floor drain) are permitted for bathrooms on the same floor level, not between floors.


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## Beepster (Oct 19, 2009)

I had the inspector out last week looking at the mechanical on my basement build out. I had him specifically look at the stand pipe and he told me that the standpipe did not need to be vented to above the sink drain as it is in the picture in the post up above. Don't remember his explanation. 

B


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## TheEplumber (Jul 20, 2010)

Beepster said:


> I had the inspector out last week looking at the mechanical on my basement build out. I had him specifically look at the stand pipe and he told me that the standpipe did not need to be vented to above the sink drain as it is in the picture in the post up above. Don't remember his explanation.
> 
> B


I'm not following your comment. Any p trap needs a vent- whether its a common vent, wet vent, combination wet vent, etc. depends on the application.
A standpipe is simply an indirect waste receptor for the washer or an extended tailpiece- whichever you prefer to call it. Vents go downstream of the trap.


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## Beepster (Oct 19, 2009)

The laundry sink vent will be the vent to the p trap. 

I was saying my inspector told me I didn't have to branch off before the p trap drained into the vertical laundry sink drain and tie in above the laundry sink drain.

I specifically showed him the image in my previous post and he said that was fine.

B


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## hammerlane (Oct 6, 2011)

Beepster said:


> The laundry sink vent will be the vent to the p trap.....I specifically showed him the image in my previous post and he said that was fine.


I looked at the image in your previous post and I do not see any laundry sink stub out.


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## hammerlane (Oct 6, 2011)

Beepster said:


> I had the inspector out last week.....the standpipe did not need to be vented to above the sink drain as it is in the picture. Don't remember his explanation.


But there is nothing incorrect about the revent of the standpipe as shown in green in the photo. Also depends on the length of the branch drain...shown in red in the photo.


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## Beepster (Oct 19, 2009)

Yes, the revent. I was saying that my drain (red line) was a short enough distance that I was told i didn't need the revent. 

Yes, there is absolutely nothing wrong with the revent. Just extra unnecessary work. 

I was only pointing out that the revent may not re required in all circumstances.

B


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## Perry401 (Apr 26, 2011)

Sorry for opening up this thread again after so long after the last comment, but I was wondering about the revent shown in the previous post photos. I was under the impression (and I certainly could be wrong) that normally the revent line needed to rejoin the stack above the height of the overflow of the fixure being served. (I understand that there are some exceptions for use in places like a island kitchen counter where other methods are used.) In the picture, it appears that the top of the washing machine standpipe is above the revent tie-in point to the stack.

As it was explained to me, the reason the revent line tie-in point should be above the overflow level was to prevent the revent line from becoming the drain line in the event of the actual drain line being plugged up at a point downstream from where the revent line ties into the drain line. If a plug occurred in this area, drain water would seek it's own level, and would flow up the revent line, across the horizontal portion of the revent line, and then down the stack to the primary drain. 

Obviously if the revent show in the pictures is wrong, it might be possible to just cut it a bit off the standpipe and still be within the limits for the standpipe height and distance from the trap weir, and simultaneously get the standpipe overflow height lower than the revent height. 

I guess my questions are:

1. Does the revent tie in point on the vent stack always need to be above the overflow level of the fixture it serves (except for the special cases like island kitchen sinks)?

2. Do different rules apply (or are different arrangements normally acceptable) for washing machine standpipes and revent lines?


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## Benplumbing (Oct 1, 2013)

Where the vent ties in from the standpipe back into the vent stack is usually a minimum of 38 inches above finished floor or two inches above the flood level rim


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## Ghostmaker (Mar 2, 2013)

*905.5 Height above fixtures. *A connection between a vent pipe and a vent stack or stack vent shall be made at least 6 inches (152 mm) above the flood level rim of the highest fixture served by the vent. Horizontal vent pipes forming branch vents, relief vents or loop vents shall be at least 6 inches (152 mm) above the flood level rim of the highest fixture served.

So to answer your question the individual vent on the washer standpipe would be to low because it ties in below the flood level rim of the fixture served.

There is no such thing as a revent line.


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## Benplumbing (Oct 1, 2013)

Ghostmaker said:


> 905.5 Height above fixtures. A connection between a vent pipe and a vent stack or stack vent shall be made at least 6 inches (152 mm) above the flood level rim of the highest fixture served by the vent. Horizontal vent pipes forming branch vents, relief vents or loop vents shall be at least 6 inches (152 mm) above the flood level rim of the highest fixture served.
> 
> So to answer your question the individual vent on the washer standpipe would be to low because it ties in below the flood level rim of the fixture served.
> 
> There is no such thing as a revent line.


Is this IPC code... Here in Wisconsin it's a little different I guess (2" above flood level rim) but we're slowly starting to conform and probably going to adapt the IPC...


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## Benplumbing (Oct 1, 2013)

See (15)(b)3.


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## Benplumbing (Oct 1, 2013)




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## Benplumbing (Oct 1, 2013)

What I think the inspector was saying to him was that he did not need to individually vent the trap for the standpipe because in the inspectors eyes he already had a vertical wet vent. Code here in Wisconsin is not the same as IPC but our code reads that the vertical wet vent can be accomplished by.. The drain between the two fixtures she'll be at least one pipe size larger than the upper fixture drain but not smaller than 2 inches in diameter. Soooo all that being said the pipe would have to be 3 inches 2 meet what venting codes. So doing an individual event for the standpipe is the best route given the pipe coming up to the floor (looks to be 2" c.i.)


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## Ghostmaker (Mar 2, 2013)

Benplumbing said:


> Is this IPC code... Here in Wisconsin it's a little different I guess (2" above flood level rim) but we're slowly starting to conform and probably going to adapt the IPC...


Yea it's IPC Ben I call it handy man code. I think the UPC is a better code.


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## Javiles (Dec 12, 2011)

Another post back from the dead :sleep1:


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## Ed Jay (Dec 25, 2011)

*Dizzy with all the pictures.*

I have a very simple application. A small utility building, stand alone, just for a laundry room is getting plumbed for a washer and laundry sink. I do NOT want to penetrate the roof. Can I just set my washer hook up box, plumb it with 2" and drop down to a p trap then connect to what would be the vent stack/ drain going down and up but what I would like to do is just take the vent pipe up to the inside of the roof level, make a 180 degree turn and head it through the floor and just put a screen across the end to keep critters out. Can I do this rather than making the roof penetration. The only thing that will vent through this is the washer and the laundry sink, no Head. I have heard I could use the screw on vent cap and do away with the 180 turn but would rather not. There is no code where I live, it's every man for himself. Thanks.


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## Ghostmaker (Mar 2, 2013)

john_bry said:


> Can the washing machine drain line be wet vented to the utility sink vent?
> My utility sink has a dedicated 2" vent.
> 
> Thx!


Cannot wet vent with either fixture.


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## Ghostmaker (Mar 2, 2013)

Westsail434 said:


> I have a very simple application. A small utility building, stand alone, just for a laundry room is getting plumbed for a washer and laundry sink. I do NOT want to penetrate the roof. Can I just set my washer hook up box, plumb it with 2" and drop down to a p trap then connect to what would be the vent stack/ drain going down and up but what I would like to do is just take the vent pipe up to the inside of the roof level, make a 180 degree turn and head it through the floor and just put a screen across the end to keep critters out. Can I do this rather than making the roof penetration. The only thing that will vent through this is the washer and the laundry sink, no Head. I have heard I could use the screw on vent cap and do away with the 180 turn but would rather not. There is no code where I live, it's every man for himself. Thanks.


No without something venting you will pull traps.


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## Javiles (Dec 12, 2011)

AHH Ghost this is a ghost thread from the past.:whistling2:


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## Ed Jay (Dec 25, 2011)

*Just to be clear on inverted air vent*



Ghostmaker said:


> Yea it's IPC Ben I call it handy man code. I think the UPC is a better code.


Thanks Ben for the quick response. Just to be sure I understand about pulling p traps and such let me please add. The washer would be plumbed with a p trap as well as the laundry sink. One on each side of one another. Not at the same elevation. The 2" drain would then come out of the connection where the two p traps tied in to the drain. Above the p traps there would be the normal air vent stack that would go through the roof. Instead of making that roof penetration I would rather go through the floor. Thoughts were to just make a 180 turn at ceiling height and head it straight down through the floor. I don't understand how wet p traps or pulling traps would happen. It not this way how can I prevent from a roof penetration or upper wall penetration. Can I use a screw on vent cap? Hate to do that because that leaves any odor in the utility building. Any more advice? Thanks


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## Ghostmaker (Mar 2, 2013)

In plan english unless your feces does not stink you need to go out of the building with the vent.


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