Tile floor around toilet flange on subfloor

[Thunderbird_ESQ]

I have pulled up the linoleum floor in a small bathroom and plan to lay down tile. The subfloor is 3/4" plywood, and I intend to lay down 1/2" backer board and tile over that with 3/8" tile. The cast iron toilet flange is screwed on flush to the plywood subfloor. Can I leave it in place, and place the backer board and tile around it, and use extension and/or thick wax ring? Given that the flange is 1/4" thick, the finished tile floor would lie 1" above the height of the flange (if my thinset estimations are correct...

1)Are my estimations for thinset correct?

2)Can I get away with 1/4" backer board? (this would help with threshold issues too, since I'll be 1 3/16" above the halway wood floors if I use the 1/2" backer...)

3)Is it OK to have the toilet flange 1" below the finished floor?

Tile: 3/8"
Thinset: 1/4" (?)
Backer: 1/2"
Thinset: 1/8" (?)
Subfloor: 3/4"

Stable subfloor=1.25" with 1/2 backer; and 1" with 1/4" backer...
Thank you!

[johnjh2o]

One inch is to low. You can use flange extensions that will bring it up to the right height. There on the bottom of the page.
Toilet Flanges from the most FAMOUS Internet PLUMBING SUPPLY


John

[Fansplumbing]

I've got some experience laying ceramic tile. You're really going to want to put 1/2" backer board down. You can use 1/4" on walls but the floor's going to carry more weight and a thin backer board will sometimes result in cracked tiles.