# help with plumbing question



## oneknot (Nov 8, 2012)

I am doing a job for a customer with a complete kitchen tear out. The old vent stack is about 4 feet from the kitchen sink, and had the drain pipe running outside the wall over to the sink. The old pipe ran inside of the original built in cabinets, and the home owner doesn't want their new cabinets butchered up. My suggestion was to run the 1 1/2 drian straight down through the floor and to tie into the basement wash tub line. 

Is there an issue with this since both were originally on the same sanitary stack? Should I put an AAV in under the sink? Will this cause a backflow into the wash tub if I attach to a sanitary cross 6 inches below the wash tub?

Any help would be greatly appreciated.:clap:


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## Sir Mixalot (Jan 6, 2008)

I'm gonna move your question over to the Plumbing section. :thumbsup:


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## Oconomowoc (Oct 13, 2011)

Hold on. I'll scribble a quick drawing.


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## Oconomowoc (Oct 13, 2011)

Under the cabinet


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## Oconomowoc (Oct 13, 2011)

Both floors tied together. There's many ways to do it, this is one option.


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## Oconomowoc (Oct 13, 2011)

Stack is still through roof? It could also look like this.


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## Oconomowoc (Oct 13, 2011)

If you run the vent like this be sure to tie it 38" from the floor or 2" above flood rim. I make it a habit to tie everything in at 40".


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## Aaron Berk (Jul 10, 2010)

Wow, awfully generous information sharing tonight! 

Can I ask a question too?

2" vent stack with a 4way cross tee that has a sink basin on either side, can I add a tee above that one and tie a washer drain into it?

Or will the washer siphon out the sink traps?


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## Oconomowoc (Oct 13, 2011)

It's possible but really pointless to use both a normal vent and a AAV. Always try and hard pipe it if possible.


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## Oconomowoc (Oct 13, 2011)

Aaron Berk said:


> Wow, awfully generous information sharing tonight!
> 
> Can I ask a question too?
> 
> ...


No, because that cuts off the vent to the lower sink basins.

Hold on


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## Oconomowoc (Oct 13, 2011)

Is this what you currently have?


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## Oconomowoc (Oct 13, 2011)

Are these fixtures on the same floor level? All 3?


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## Aaron Berk (Jul 10, 2010)

Because every one loves pictures..... (self included)

Here is the wall.

All on the same floor. 
The wall on the right with the outlet is getting furred out and turned into a wet wall.


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## Oconomowoc (Oct 13, 2011)

Got it. Hold on a minute


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## Oconomowoc (Oct 13, 2011)

Is this possible?


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## Aaron Berk (Jul 10, 2010)

I can do that, but doesn't my trap have to be 6" or something above the floor?

And yes.... this is my house. in case you we're wondering :whistling


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## Oconomowoc (Oct 13, 2011)

Not in Wisconsin. Did you want a standpipe or a washer box?

If your state requires 6" clearance (that's strange) you can also do it with a wye fitting. I'll draw it quick.


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## Aaron Berk (Jul 10, 2010)

Oh DUH!
Never mind about trap height, I can put it where it needs to be, and plumb in a 22.5* or what ever.


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## Aaron Berk (Jul 10, 2010)

Washer box, but it has a stand pipe in the middle, .... right?


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## Oconomowoc (Oct 13, 2011)

You can get more clearance sometimes with a "wye" fitting like the drawing bit it's totally pointless. Just use a 2" x 1 1/2" T and keep it up. Lavs are tied in high so you have plenty of room.

WARNING: Make dam sure that line for the lavs isn't a wet vent for the toilet. If that's the case you CAN NOT do this. At least in Wisconsin.


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## Oconomowoc (Oct 13, 2011)

You don't need to run the entire drain in 2" by the way. Just the standpipe.

Hold on


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## Oconomowoc (Oct 13, 2011)

Vertical portion of standpipe is 2"

Rest is 1 1/2". This has been done this way forever in Wisconsin and is code compliant.


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## Oconomowoc (Oct 13, 2011)

Set top of box at 42".


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## Aaron Berk (Jul 10, 2010)

plethora of knowledge Mike, and friendly ta boot..:whistling


The lav vent has it's own stack, but they all tie into a single 3" stack up in the attic .
This house is plagued by a few slow drains though......
It was built by a builder for himself, but he cheaped out on most every thing.


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## Aaron Berk (Jul 10, 2010)

Oconomowoc said:


> Vertical portion of standpipe is 2"
> 
> Rest is 1 1/2". This has been done this way forever in Wisconsin and is code compliant.


All your other pics show a vent on the washer waste line, but this one doesn't?
It is still needed right?


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## Aaron Berk (Jul 10, 2010)

ut oh, Momma's calling.....

Night.
ty for the info


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## Oconomowoc (Oct 13, 2011)

Yes, you need the vent like the other photos. I left it off in the last photo just to show sizes and where they changed. 

Every fixture needs a vent. Period. 

If you have any more questions let me know. I'll always answer plumbing questions if I happen to see it. I don't spend much time in this section.


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## oneknot (Nov 8, 2012)

Here is what I had in mind.


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## Aaron Berk (Jul 10, 2010)

This one's for you Mike.

And yes, I have nail plates too


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## Oconomowoc (Oct 13, 2011)

Nice job.

Question. How high is the top of the box and how high is the vent tied in at from FF?


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## Aaron Berk (Jul 10, 2010)

top of box 52

FF is that for Fernco Fitting?


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## Aaron Berk (Jul 10, 2010)

I set the box so high in an effort to clear the junk sticking out on the back of my stackable combo.


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## Oconomowoc (Oct 13, 2011)

FF= finished floor

52 is pretty high, 42" is normal. I would bring that down 10".

The vent should be 38" FF or 2 " above flood rim level (top of sink on back wall.

That's Wisconsin code.


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## Oconomowoc (Oct 13, 2011)

Aaron Berk said:


> I set the box so high in an effort to clear the junk sticking out on the back of my stackable combo.


I see, just be sure the discharge will make it Aaron. The vent should really be a changed but in that application it's not life or death. 

Just remember in the future you want vents to be tied above sinks. 40" is always a safe number. 

If you are ever stuck on something email, text or message me.


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## Aaron Berk (Jul 10, 2010)

My vent ties in at 34"

My sink on the other side is at 32.

So despite my obvious lack of plumbing skills, will it work


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## Oconomowoc (Oct 13, 2011)

Sure. You did a fine job Aaron. It will work well.


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## rex (Jul 2, 2007)

Flood rim 42 here.

Not a fan of the ferncos.


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## Oconomowoc (Oct 13, 2011)

rex said:


> Flood rim 42 here.
> 
> Not a fan of the ferncos.


How high do you set the top of your boxes Rex?


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## rex (Jul 2, 2007)

36 to the bottom.


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## Aaron Berk (Jul 10, 2010)

rex said:


> Flood rim 42 here.
> 
> Not a fan of the ferncos.


In my limited experience I've only come across 1 failed fernco. 
And it was connecting cast iron to pvc and bricked up behind a wall and covered in mortar.

It was a 3" waste line and was dumping sewage between the house and brick siding 

Guess it had been there about 10yrs, and leaked for 4.


I'm okay using them in this type of application, I would think twice before using them on a horizontal plane. My 2 cents.....


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