Tie in to 3" copper stack question

[Andrew M]

I am at the end of building a master bath. I used 3" PVC for toilet, shower (2") and sink (1 1/4") feed into this. The existing soil stack is 3" copper to municipal sewer. I intend to tie into the 3" copper vertical drop with my PVC. In talking to a plumber a while back he said when I do this to use a fernco and a compression. Question is, I am not quite sure what he meant, and am planing on tieing to a 3" sanitary T and gluing a few inches of 3" pvc above and below, then cut out that amount of 3" copper and use connectors to put it all together. Sooo, do I use fernco on top and bottom , or was there something in his message abount a compression and a fernco that I am missing?

[Basement_Lurker]

It sounds like you know what you're doing. You want to use a shielded band coupling (like a ZIP-II coupling) to join the stubs you will glue into the top and bottom of your pvc tee to the existing cut ends of the copper stack. I guess the "compression" that you are confused about is that the band coupling uses gear clamps to make a seal by compressing the rubber sleeve onto each end of the pipe that you are trying to bridge.

The fernco couplings are usually a generic reference to rubber coupling with only band clamps that is flexible because it doesn't have a metal shield. Both the shielded and un-shielded couplings have their place. I like to use the shielded one for something like this because it will make the setup nice and rigid.

[GrumpyPlumber]

In my state fernco's are illegal...gotta be the shielded type...and as Basement said...they make a firm connection with no play.

[Andrew M]

Ready to Glue and screw. Just want to run this primitive diagram by you. My main concern is the configuration of a 30 degree off vertical drop of 2' to a 60 degree elbow which is joined to the santee with 2" of horizontal. Is this ok? And secondly, how can I be sure I have a santee ?

[GrumpyPlumber]

The picture wouldn't open.
You're asking about san tee's so I'll simplify.
There's only one way a san tee can be used on drainage...thats when a horizontal drains feeds into a vertical (a drop)...NOT on horizontal changes, NOT on vertical to horizontal.
A sanitary tee is like a wye fitting...with the difference being the san tee has a 90 degree turn built into it...a wye has a 45 thats intended to be connected to a regular 45 fitting to create whats called a "long sweep".
Also...on this bathroom...have you vented the drainage?

[Andrew M]

Yes I have vents in both the shower and toilet to the attic and then 2" to 3" through the roof. The new horizontal 3" is 2 joists away and above the existing copper. I was hoping to cut into stack, place santee, come off that a couple of inches to put a 60 degree elbow in then from that elbow head about 30 degrees vertical for a foot and a half to the new Horizontal which is about 14" vertical above place to put santee.

Not sure why pic does not work

[Andrew M]

Yes I have vents in both the shower and toilet to the attic and then 2" to 3" through the roof. The new horizontal 3" is 2 joists away and above the existing copper. I was hoping to cut into stack, place santee, come off that a couple of inches to put a 60 degree elbow in then from that elbow head about 30 degrees vertical for a foot and a half to the new Horizontal which is about 14" vertical above place to put santee.

Not sure why pic does not work

[Andrew M]

I have reinserted. Hope you can see drawing

[Andrew M]

So are you suggesting I use a wye with a 45 ? I thought using a wye on the vertical was a no no.

[cwhyu2]

You can use a wye in ether way.go to your local ************** and ask
for copper to pvc couplings.I know they have them as Ihave used them many times.the wall thickness is different.Afernco would work not recemened.
hope it works