So you want a controlled residential ventilation system in a house where you don’t trust the builder to plan such a thing. For this purpose, a specialist planner with expertise in controlled residential ventilation is supposed to get involved in the mess of the builder-planned ceiling, and then the planner or a third party is supposed to carry out the installation. Whether you’ll still love yourself afterward, I’ll mark that with a question mark; at least you might be inclined to form a self-help group with (who, however, did not leave you a warning example here regarding controlled residential ventilation, but his range hood was apparently no walk in the park either) ;-)
Alright then (or not alright, but doable with lots of praying), let’s run through the story— to my memory (and except for kitchen and financing threads, I basically know all threads here since I joined and had looked back about a year at that time) unfortunately without any "role models" in this (and also in the green) forum:
So let’s start from the ceiling of the previous planning. The controlled residential ventilation ducts don’t weigh much, so the ceiling won’t have to be structurally reinforced specifically for that. In the worst case, the floor construction above the ceiling might become thicker, which would also affect the staircase—but only linearly, since it would be the same on both floors, keeping the story height as the distance from the top edge of the finished floor on the ground floor to the top edge of the finished floor on the upper floor the same—the staircase would then just have to be "set" higher accordingly. The previously not planned controlled residential ventilation could also have corresponding consequences for the underside of the ceiling. This effect might be minimized if, for example, it is coordinated with outlets for ceiling spots or access points. In any case, it should be very clear before ordering the ceiling and planning the reinforcement at which points the controlled residential ventilation planner foresees ceiling penetrations. And I would also warmly advise you to coordinate the installation of the controlled residential ventilation into the construction site process. If you make controlled residential ventilation a “the general contractor has nothing to do with this” trade, the measure will ultimately be a first-class self-flagellation!
Keep in mind: we are talking here about a loss of clear room height of only a few centimeters—so refrain from increasing the story height (unless the rooms would otherwise be too low according to your state building code), since this would mess up the staircase planning and with that possibly ruin the layout at critical points (classic example: distance between staircase exit and bathroom door frame).