A basic principle in providing good security is a concept known as “Concentric Circles of Protection”. This is sometimes referred to as “Security in Depth”. This concept involves the employment of “rings” or “layers” of security. The first layer of security is the boundary of the property, and additional layers are provided as you move inward through the building toward high-value assets.
Rather than depending on a single layer of defense, multiple layers make it necessary for an intruder to penetrate a series of layers of defense. The more layers of security that exist between the perimeter of the property and a targeted asset, the better the security.
The concept of concentric layers of security is illustrated below. At each boundary or layer, there is an opportunity to deter, detect and delay an intruder to the property.
The basic principle for employing multiple layers of security is to minimize the need to depend on a single layer of security. As illustrated in the example above, an intruder who breaches an exterior door needs to breach at least two additional layers of security before reaching an asset of value.
Concentric layers of security provide redundancy in case prior levels of security are overcome. While the chance of a breakdown of security may occur, the chance of breakdown of successive security procedures or layers is less likely.
A minimum of three (3) layers of security should exist between the perimeter of the property and desirable assets, with five (5) or more layers being preferable.
Principles of Concentric Layers of Protection
- Having multiple layers of security decreases the probability that an intruder will be able to steal a valuable asset.
- You can decrease an intruder’s chance of success by increasing the number of layers of security.
- A single layer of security is seldom effective by itself in deterring a determined intruder.
- Employee security awareness can serve as an effective concentric layer of security.
