I'm installing a toilet in the basement of the house where a plumber "roughed-in" the full bath. Everything looks good, except where the toilet flange should be, there is the drain pipe sticking up with a domed end on it. No cap, just a half-round end of the pipe that looks to be a cap for pressure testing. But, it's not a cap. It looks like it was connected to the pipe under the floor. The tile floor is finished to about 1 inch above the top of the drain pipe. It this a knockout cap? Or do I have to cut the domed end of this pipe off to install the flange to the drain pipe? It doesn't feel like PVC. It almost feels like ceramic. It was roughed in about 7 years ago when the house was built.
Any help would be appreciated... A.G.

HI Guedela...

A picture would really help...

If the pipe is the only large pipe coming out of the floor and it is between the rough in for the sink and tub/shower (if present) then most likely it is the toilet and the cap just needs to be cut off.

If the location is questionable, then it could be a BACKFLOW PREVENTER.

How big is this pipe/noncap/cap?

Post a picture if you can...

Mark

Thanks for the reply... It's definitely the floor drain for the toilet. It is between the lavatory rough-in and the tub/shower unit. It is in front of the stub out for the toilet water supply line. I'm not at the residence, so a picture isn't doable right now. I'll travel to the house and take a pic .It's 4 in in diameter (outside) and a little below the finished floor.
There's no way to get a hack saw into the opening to cut off the top. A Dremel tool with a cut-off wheel will work. But I think it was designed to be "knocked out". It feels very thin on the top of the dome and it's not a cap , per se, it's a molded dome on the top of the pipe. I can't see or feel a lip for 3 to 4 inches down the pipe. YIKES!

Sounds like a test cap for sure...

Use a dremel or drill to get a hole started and then just pop that cap off.

You will probably need a 4" twist and set closet flange to finish the job... see image. Use a wax gasket with horn and 5/16" closet bolts to set the toilet.

Let me know what you find...

Thanks so much. I really didn't want to start hacking on that pipe without checking with someone. Every rough-in I ever saw had the flange with a knock-out already installed. I will definitely use the twist and set flange. Ill keep you informed...

Thanks for posting back...

Mission accomplished. I just didn't dig out enough of the styrofoam they put in to keep the concrete back from the cap. It was a solid cap on the end of a 3 inch drain stack. The drywallers had sprayed so much texture in the room, it coated the cap and kind of "camoflauged" it .I drilled a hole in the top of the cap and when I saw how thick it was, I could tell it was just a cap on the pipe. I dug out a little deeper and could feel the lip of the cap. A little persuasion with a set of large channel locks did the trick. A trip to the plumbing supply for a flange with an extended tailpiece was all that was needed. Tapcons into the concrete through the flange secured the whole thing. Toilet went on with minimum shimming and it works like it should. Thanks for all the help... A G

Glad you are all set!