No floor number on the door.

No stairway designation on the door.

Re-entry is required every four floors, so "No re-entry on floors 9-13" 
means either the sign is wrong, or there are too many locked floors.

Since a keyhole is visible, a key may be required on this floor (8)
as well (which would mean that the re-entry sign is wrong). 
This would have to be checked.