The bathroom has a mortar bed floor about four inches thick, supported by some wood planks between the joists. On top of this was layer of damaged mosaic tile. I tried removing the tiles, couldn't get them up, so I put a layer of Hardibacker over it, which was held down with thinset, then I tiled over it. The floor has been fine for almost twenty years.I needed to replace the toilet and picked up a standard 12" toilet, not realizing that the old one was 10". I chipped out a couple of tiles and enlarged the hole on one side. The old closet bend and flange were a mess so I tossed them and put in new pieces.When I went to screw in the flange to the floor, the mortar bed began crumbling, anywhere I drilled in would break off. There's nothing to hold the flange in place.My thought is that I can cut out a few more tiles and cement board until I reach solid a solid part of the mortar a few inches from the hole, then put thinset on a piece of exterior plywood in place. It will go in in two pieces so it can slide under the flange and closet bend. Then I can put in a few leftover tiles to get the floor roughly even, screw the flange into the plywood, and set the toilet in place.Does this sound like something that's going to work? Does anyone have another suggestion? via /r/DIY http://bit.ly/2ByxMoR
