closed-door policy

(noun)
The policy wherein the occupants of an office or room keep the door closed so as to limit the amount of annoying intrusions, which may consist of people wandering in or simply the to shut out the annoying noises that are made in the hall.

"Zach and Evan have a closed door policy after that girl came in and would not shut up."
"Dude, shut the door, closed-door policy!"