Classifying zones by access, not by size
The public foyer, the counter line, interview rooms, the general office floor, the records room and the server cupboard are all different access classes even though several may be within a few metres of each other. Classifying them properly is the first step, because it determines who can do the work, when, and whether a second person needs to be present for it.
A useful classification has three levels. Open areas can be cleaned during or after hours without supervision. Restricted areas require a nominated cleaner and a recorded entry. Excluded areas are not cleaned by the contractor at all and are handled by the client's own staff. Most buildings need all three, and most disputes come from having never written them down.
