Toilet flange mounting question

[TREY71105]

I have the Oatey twist & set flange but my question is about mounting it. It will be mounted over ceramic tile but it's a 70 year old house so the bathroom floor is 2-3" of drypack before you get to the slab. Will using a hammer drill for tapcon screws compromise the structural integrity of the drypack? How else could I mount it?

 

[Twowaxhack]

Use 5-6” tapcons. Drill into the slab. Shouldn’t hurt the drypack

 

[Geofd]

The tap con package will provide the proper drill bit , you can also buy tile bits, they almost look like arrow tips use them just to drill through the smooth top coat