North Carolina does not require school exterior doors to be locked. Its statewide door commands are fire-safety commands with a real paper trail: principals must inspect every building at least twice a month and file a monthly written report, every public school building gets an official fire-prevention inspection at least twice a year on State Fire Marshal forms kept on file for three years, and willful failure of these duties is a Class 3 misdemeanor. The fire statute also requires that doors needed for orderly exit be kept unlocked while the building is occupied.
The verified texts: G.S. 115C-288(d) puts the principal in every building at least twice a month with a monthly written report; G.S. 115C-525(b) adds the official fire-prevention inspection at least twice a year, at least 120 days apart, reported on State Fire Marshal forms and kept on file for three years.
That makes North Carolina an inspection state like Texas and Ohio rather than a locked-condition state like Tennessee or New Jersey, and its inspection clock is the densest of the three: the principal-level check runs twice a month, every month of the session.