Not clear on what you are asking. Typically a toilet flange doesn't attach to the tile, it attaches to the drain components and then is screwed into the substrate, generally through the tile. The flange can sit atop the finished floor and that is preferable but not necessary all of the time. There are also flange extenders and additional wax seals can sometimes be used to build up for the connection of the toilet to the flange/drain.

 

I need to screw down my flange. I just finished tiling over 1" of concrete (radiant floor heat)

Do I need to get concrete screws or drill through marble, concrete and screw to the wood subfloor? of so, do I need any special bits?

 

I would pass through the tile and concrete and screw the flange into the subfloor.

 

Yes, aim for the subfloor. You need to use a masonry bit to drill holes through the tile, ditra, and concrete. The bit needs to be large enough to keep the threads of the screws from engaging the tile. Be sure not to drill down through the subfloor with the masonry bit, as the hole would then be too big. Use wood screws (probably #14 or so) to secure the flange to the subfloor.

 

Cheers

 

I hope your radiant is at least 6" from the wax ring!?

 

Whoa! didn't even think of that! I think I am at least 6" away.