The demise line is the whole answer
Almost every question about who cleans what resolves back to a single line drawn in the lease or the strata plan. Inside it is the occupier's responsibility, outside it belongs to the base building and is funded by the owner or the scheme. The trouble is that the line is a legal one rather than a visual one, and in a fitted-out floor it can run straight through the middle of a space that looks entirely continuous to anyone standing in it.
Facilities officers new to a building are the ones most often caught out by this. They assume the shared corridor on their floor is theirs because their staff are the only people who ever use it, or they assume the shared amenities are somebody else's because they sit outside the front door. Reading the demarcation before writing a scope prevents both mistakes and takes a small fraction of the time that unpicking them later does.
