With all the attention being paid to electronic gadgets these days we sometimes lose sight of the basic elements that establish security, perimeters.  What is a perimeter; in security we define it as:

… A contiguous set of barricades such as walls, doors and natural features (like a rock face or the side of a mountain) that completely surround an asset being protected 

Everything within this surrounding perimeter is considered the protected assets.

Perimeters are arrayed in concentric circles of protection and begin at the most valuable asset.  Begin with the item you most wish to protect and establish a perimeter this way.  Trace the unbroken wall line from a starting point through 360 degrees around the asset; note any openings in this perimeter such as doors and windows.  This is your primary security pereimeter.

This should be the most secure of all the perimeters and, depending on the value of the asset and the consequences of loss, it may be necessary to reinforce this perimeter.  For example, if the perimeter consists mostly of dry wall, it can be breeched in less than 2 minutes with the proper tools.  These walls can be reinforced with wire mesh adding to the delay time to gain access.

Next consider the “moveable” barricades, doors and windows.  Presumably your most valuable asset will not be in a room that is adjacent to an exterior wall so there will be no windows but that is not always true.  A window on a primary perimeter should be turned into a wall from a security perspective.  Do not rely on the strength of the glass or on detection devices to secure the window.  If this is your primary perimeter you must secure that opening with mesh, bars or other difficult to penetrate coverings.  Also pay close attention to the manner in which these coverings are attached to the surrounding walls.

Likewise, special attention should be paid to doors.  Notice which side the hinges are on, protected or unprotected.  Remove a hinge screw to see how long it is; is it simply mounted to the door frame or does it penetrate all the way to the stud wall?  How substantial is the hinge, is the metal thin and pliable or thick and ridged?  What about the door itself, from what material is the door made, how thick is it, which way is the “swing”?  Doors require special attention and should be examined by a security professional if they will be used as a control point in a primary perimeter.

Provide access control at every opening and use door status switches to monitor the status of the opening.  The access control devices used may be a simple keypad (the lowest form of control) to biometric measuring devices the most secure.  Again, depending on the asset value and criticality, multiple access control devices may be used and in some cases a 2-man rule.  A 2-mail rule means that there must be more than one person authorizing access at the same time for someone to enter.

Inside the protected perimeter you can add sensors to detect the presence of intruders.  Some sensors are based on heat, others on motion and still others on visual detection.  Pick the solution that is right for the environment and the asset being protected.

After establishing a secure perimeter around the protected asset, identify a second perimeter that completely surrounds the first perimeter.  Perform the same examination and provide the same controls except here the control devices can be moderated and reduce the cost of security for this area.  Likewise the attention to structural requirements for the doors and walls are less stringent.

Continue in this fashion, building perimeter around perimeter, until arriving at the outer perimeter boundaries.  In high security facilities, this too is made very secure since the outer boundary is the first line of defense against intrusion and criminal activity.  Open areas can be protected by electronic fences (sensor grids), physical fences or a combination of both.  The type of fence selected and the level of sensor detection depends in part on the anticipated intrusion.  The more determined the intruder, the more structured should be the security.

One of the basic elements of a good physical security plan is a solid set of controlled perimeters.  If your security readiness meets this first test you are well on your way to having a secure facility.