The Sims 4 actually allows (-1, -2, -3, -4) plus the ground floor plus 4 upper floors. That is 9 functional floors total (4 up + Ground + 4 down).
The Sims 4: Building a (functional) fifth floor (fully roofed!) sims 4 more floors mod work
Here's a step-by-step guide on how to use the mod: The Sims 4 actually allows (-1, -2, -3,
: This is the primary tool for "cheating" height. It allows you to elevate, rotate, and move objects (including windows, doors, and floor panels) far beyond their standard grid restrictions. Better BuildBuy (by TwistedMexi) The Sims 4 actually allows (-1