I'm adding a shower to a half bath rough in. When I dug up the concrete to expose about 18" of a 3" PVC drain pipe, I realized I had a problem. How do I attach a wye if the ends I cut have no slack? I've read some about ferncos and couplings, but not sure about burying them underground, etc.

I would think this would be a pretty common situation, but I haven't seen much on here that spells it out.

Thanks for any input.

You need a shielded coupling, Fernco is a brand name of a company who makes couplings and many other items. Not all couplings made by Fernco would meet your needs. Tom or Milo might be along soon and they have some pics to help you. Basically you cut out a section of the 3" pipe and install your wye on one of the ends in the floor. A short section of 3" is added to the other end of the wye nearly filling the gap caused when you cut out the pipe, the shield no hub coupling joins this new short pice with you old pipe in the floor.

Ballengerb said it: proceed as he advised. You can use both Shielded No-Hub coupling or Fernco coupling as well.

Guys, thanks for your answers, they helped a ton. I'm done, and poured my concrete today. I didn't like the idea of leaving 6" of a hole around the new drain pipe for drain assembly though. I foresee(maybe incorrectly) that that type of a gap could cause cracking of the pan eventually since there is no support. So, now I have my 2" stub sticking up 10" or so out of a level concrete floor. Was I wrong? Did I screw up? How can I attach a drain properly given what I'm looking at? I was planning to put some type of foundation mix or plaster into my shower opening before I set my pan(per instruction) Will this give me ths space I need>?

Any more help is appreciated.

If you are using a fiberglass shower pan, the support is formed into most of them. You can add extra support between the support ribs by using mortar.