Where I live, the common construction for houses is to have reinforced concrete slabs as the floors and ceilings, with the walls being brick except for the load-bearing reinforced concrete columns. The ceramic tiled roof (when there's one) goes above the reinforced concrete ceiling. More than once, I've read about accidents in which Brazilians fell (sometimes to their death) through the ceiling of a USA home, and that's because we simply don't expect the ceiling to be so fragile; our intuition is that the ceiling is as strong as the floor, and that we can walk normally over it.

To those from countries with a similar building culture, USA houses feel really fragile; for instance, what do you mean you can punch a hole in a room's internal wall? We expect these walls to be made of brick.