Tie in to 3" copper stack question

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?

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.

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 ?

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

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

I have reinserted. Hope you can see drawing

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

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