Toilets- Can I put 2 toilets back to back on a double tee?

[markcool]

I'm roughing in a 2nd floor master bath with his and hers powder rooms. The toilets are back to back, with a partition wall in between.

Can I use a double tee fitting, and run the closet bends straight into it inside the joist bay?

The vent would rise vertically inside the wall, and the stack straight down into the crawlspace through the 1st floor wall.

Thank you,

Mark

 

[johnjh2o]

Mark it's not a good idea, although it is excepted by most codes. If you have the room you would be much better off using a DBL Y with 45's. What we are starting to see with back to back set ups, is the new 1.6 and 1.28 toilets flush so fast that they bubble up into the adjoining toilet when using a DBL sanitary tee. I'm sure that the codes will some day catch up with this new problem and make the changes that are needed.

John

 

[markcool]

Thanks again John.

That makes sense about the double wye and 45's. I have it roughed with the tee, so I may leave it, since I'm working inside a wall from above.

 

[phishfood]

Actually, International Plumbing Code, which is the model code for Florida, specifically prohibits double sanitary tees on back to back water closets, unless there is at least 30" of pipe from each side to the toilet.

 

[markcool]

Wow, I may have to re-do it then. Is there a minimum distance between the closet bend and the 45?

These toilets are back-to-back, separated only by a partition wall. That means I have just 12" on either side of the stack.

 

[markcool]

I deleted my double tee and installed a 3" double wye for the back to back toilets.

I have the toilets roughed in with a short straight piece of pipe, then a 45, then a 3" 90. I plan to use the flanges that fit over the 3" hub, as I'm working in 2x6 joist bays and this is the only way I've been able to stay flush with the finished floor.

Is this all kosher?

The main question for me is can I use a 3" 90 and an over-the-hub flange?

Cheers,

Mark

 

[johnjh2o]

Mark, what you need is a 3" street 90 and a flange that fits over 3" pipe, or a 3" street flange that will fit inside the hub of the 90. They don't make a flange that fits over a 3" hub.

John

 

[markcool]

Thanks John,

I do have a flange that fits over the 3" hub, it's a 4 x 4 spigot. Is that not allowed?

Are you saying to put a 90 street so that the non-hub side is pointing up. Or are you saying to use a 90 and finish it with a flange that sits inside a 3" hub?

I have posted some pics of my rough in here: Plumbing rough-in for attic

What I have done is the double wye with a 45, then a 90. I haven't glued anything yet, because I wanted to get advice.

Thanks again.

 

[johnjh2o]

What it looks like you have is a 4"x3" 90. If so than there is a flange that fits inside 4" pipe. It's the same flange that fits over 3" pipe. There are many different combinations that will work. As long as your flange is ending up sitting on top of the finish floor it will work fine. Just be sure to screw the flange to the floor.

John

 

[Pipedawg]

The Tee you need is called a Double Fixture Fitting (Charlotte part #500) It has a bigger radius than a sanitary tee but smaller than a double tee wye or double wye with street 45s.We use them all the time where we have to do a back to back WCs.

 

[markcool]

Thanks Pipedawg.

I have the double wye in place already. Will it fail inspection?

Hey John,

It's just a 3" 90 that you're seeing, the perspective of the photo might make the hub look bigger.

My main question is, will the wyes pass inspection?

thanks again,

Mark

 

[johnjh2o]

Mark, the Y's are great you should have no problem with inspection.

John

 

[markcool]

Thank you John.

I started with the double tee, then phish said that that was not OK with IPC, and you said there were problems with the lower gpf toilets, so I pulled it out.

I was hoping not to have to pull the wyes too.

I appreciate it.

Mark

 

[phishfood]

Just curious, Mark, what is your location? Also, let us know what your inspector has to say.

 

[markcool]

I'm in NC.

Here you can take at test at the inspections office, and if you pass, a homeowner can pull a plumbing permit.

This is what I've done. I am finishing up the drain/ vent stuff this week, and have begun working on the supply lines, using pex.

I'll keep you posted on the inspections.

Best,

Mark