Okey so I build the city for my game and rooms inside and I make the floor on the next level. Every static mesh needs to be placement in the corrent world position and it can’t touch other static meshes (floor). I use for that snap size 0,01mm and it is still not enough, so I duplicate per one object to change X or Y and Z values in Details > Transform. You may asking me why I change Z values of the same floor, because after duplicate it spawn this object Almost in the same world position.
Anyway it’s really hard to create large room and it take a lot of time.
I hope that we seen magnet tool or plugin (something like that).