What is required to obtain a TCO?

For a TCO, the DoB is interested primarily in life safety, health and welfare of any occupant of the building. Therefore any fire regs. must be complied with, whatever fire safety elements present must be up and working, and there must be at least individual fire alarms working in each apt. which might be occupied. Plus as you say functioning elevator, required clearances at entrances, doors swinging in the correct direction, fire stairs open and accessible, notices up to direct people to theml and the like, your architect can advise you. DoB not interested in completely finished spaces or any decorative devices, except they cannot be flame-producing or encouraging (in line with above).