I assume Brad Noble is just a random guy interested in development. The response is from the official DTK YouTube account so should be correct.
I read this and thought you're suppose to include Mechanical floors: "How to request a building or city"
"* Floors: Consider those that also have a roof, so the main floor is added, mezzanines, levels of distribution, attic, levels of machine rooms, levels of covering staircases, levels below the access but with windows or doors to the outside , 13th level, etc., they all add up."
https://skyscraperpage.com/forum/sho...57&postcount=5