Basically every apartment building built in the last 25-30 years that is 6 stories or less (which is the vast majority of units constructed) will be a concrete

Basically every apartment building built in the last 25-30 years that is 6 stories or less (which is the vast majority of units constructed) will be a concrete base floor and then stick built apartments on top. It’s called a 5-over-1 and it’s so much cheaper than doing five stories of metal pan and concrete deck that the economics force the decision. You see these everywhere. https://en.wikipedia.org/wiki/5-over-1 https://en.wikipedia.org/wiki/5-over-1 Anything over 6 stories will be concrete and steel, or rarely, engineered wood or timber framed. Concrete and steel apartment buildings do not have vertical concrete partitions or wood stud walls between the units, they have steel stud walls with two layers of double 5/8” drywall on each side to provide a 4-hour fire rating. I am a construction professional, FWIW.