[coredog64]

IIRC, 3 stories is about the max that US building codes allow for stick built structures. Beyond that you have to go to steel.

3-4 is also where you need to start thinking about adding an elevator. That adds to the cost and reduces the area available for units.

[ThrustVectoring]

AFAK this is what the codes are. When I see building frames under construction, I see an awful lot of "three floors of wood framing above a steel base" (usually mixed-use commercial 1st floor with residential above, but I'm assuming things here)