Toilet waste rough-in pipe too low

Hi, folks; long time no post:

I'm at the finished floor stage of my new house under construction. It's been 18 months, but seems like 10 years (dog years, I guess; I'm a vet...). Got power to the house today, and all my electric and plumbing works fine (so far). Thanks go to some of you who helped me last summer.

Changed my mind on flooring, and am now going to use tile in my guest bath. Cut off the test cap from my 4" PVC pipe stub, and then put down thinset and Hardibacker (1/2"). Pipe is now about level with the top of the Hardibacker board. Once I apply thinset and tile, it will be too low.

What would be the best way to solve this problem, so that the toilet flange will sit on top of the tile?

The subfloor is 3/4" Advantec, over a basement. I do not remember how long the riser pipe is coming up out of the closet bend; I'm pretty sure it is quite short.

Thanks in advance,
Steve

flange

The flange will be abut 2" long and slide over the pipe, so if the pipe is only a 1/2" low the flange will be more than long enough to make a good joint.

Thanks, HJ. When I dry-fitted the flange it was pretty good; the 4" stub came up to about 3/8 to 1/2" below the top. I know that it will likely slip down further with primer and glue.

With the thinset and 10mm tile, it will be another bit below that. I was a bit antsy about gluing only 1/2 of the joint.

Steve

Unless you needed it for height to align with other floors, the 1/4" cbu would have been more than sufficient since it adds nearly nothing to rigidity to the floor...next time. You could have used a membrane over the subfloor and made that an 1/8" rather than the 1/4" or 1/2", too.

Gotcha, Jim. Yes, it was for height reasons. I know that it didn't add strength. (I think I learned that from you or another of the fine folks over at John Bridge's world. You are everywhere, man!) I could've used a step threshold, I suppose, but I want the tile and grout lines to continue from the foyer and hall into the bathroom.

Steve