32 CFR 2001.53: Open storage areas.
This section describes the minimum construction standards for open storage areas.
The perimeter walls, floors, and ceiling will be permanently constructed and attached to each other. All construction must be done in a manner as to provide visual evidence of unauthorized penetration.
Doors shall be constructed of wood, metal, or other solid material. Entrance doors shall be secured with a built-in GSA-approved three-position combination lock. When special circumstances exist, the agency head may authorize other locks on entrance doors for Secret and Confidential storage. Doors other than those secured with the aforementioned locks shall be secured from the inside with either deadbolt emergency egress hardware, a deadbolt, or a rigid wood or metal bar which extends across the width of the door, or by other means approved by the agency head.
(c) Vents, ducts, and miscellaneous openings.
All vents, ducts, and similar openings in excess of 96 square inches (and over 6 inches in its smallest dimension) that enter or pass through an open storage area shall be protected with either bars, expanded metal grills, commercial metal sounds baffles, or an intrusion detection system.
(1) All windows which might reasonably afford visual observation of classified activities within the facility shall be made opaque or equipped with blinds, drapes, or other coverings.
(2) Windows within 18 feet of the ground will be constructed from or covered with materials which provide protection from forced entry. The protection provided to the windows need be no stronger than the strength of the contiguous walls. Open storage areas which are located within a controlled compound or equivalent may eliminate the requirement for forced entry protection if the windows are made inoperable either by permanently sealing them or equipping them on the inside with a locking mechanism and they are covered by an IDS (either independently or by the motion detection sensors within the area).