Once the building was at lock up, the real work began. The inside is sheeted with a round of 3/4" on the bottom and then 5/8" from there up. The ceiling is aluminum. It was a pain to put up but man is it nice now. I don't know how many screws I have driven, but there was just shy of 3000 in the ceiling alone. Ouch, ouch, ouch. The mezzanine is 12' X 32". The window in my office I salvaged from a building that was being remodeled. It was a car dealership in the past.