I've had to replace a section of the subfloor in my bathroom because the original construction crew 15 years ago broke the closet flange hammering in nails to seat it on the floor (instead of screwing it down) - it leaked for 15 years under the linoleum until mildew stains came through and I knew I had a problem.

I've put down the new subfloor, and will be putting down 1/4" backer board, then tile; my questions are:

1. How big a hole should I cut in the subfloor? The pipe portion coming down from the flange is just under 4 inches diameter, so I assume a 4" hole should be fine. Is this right?

2. There is a beveled collar at the top of the pipe portion (underneath the top flat part of the flange) - when I install the concrete backerboard, I need to make an allowance for that, don't I?

3. Same question as #2 for the tile I put down - it should come right up to the larger "collar" under the flat top, so the flat top rests on the tile, right?

4. After all that, then I should mark the spots for the screws to hold down the flange, and use a masonry bit to drill through the tile & backer board down to the subfloor, & then once the new flange is glued on, screw it into the floor. Is this correct?

Thanks for your help!

Steve

Sounds like a winner to me.

Although it would be much easier to set the closet flange to the height of the tile backer, you could then run the tile backer board underneath the collar of the flange and fasten it to the floor, and then tile up to the collar of the flange.

Unlike wall specific tile, floor tile can be very difficult to drill.

Thanks for the quick response. The PEI 5 tile I'm using is pretty tough, so maybe tiling up to the edge of the flange is the way to go - thanks for the good suggestion!