Word of forewarning: if you get any of your employees' heights over... I wanna say 13 meters, things get Wonky. Right now my 15 meter tall employee is stuck inside a wall, and another employee is stuck within a machine while a client's walking into the wall repeatedly. I figure this has to do with the models' hitbox growing with its size, so maybe I'd either change this or figure out a way to re-render the models somehow? NPCs being unable to leave means you can't end the day, so if one gets stuck inside the wall it's basically a softlock.
A way you can fix this is, when an employee gets bigger than say the doorway or a certain height, she can no longer come inside the building and has to stay outside. If you want her to do work, you then have to order special equipment just for her. Example: Outdoor treadmill/weight rack. Outdoor cash register. Or something.
Only other fix I can think of is, when an employee starts to surpass the roof, just have the roof removed the next day. Let them gals grow taller and taller!