Deter, detect, delay, respond
The four layers behind every good physical security design, in plain language.
No single camera, lock or guard keeps a site safe. Good security uses layers that work together, so a failure in one is caught by the next.
1. Deter
Make the site look like a hard target, so an attacker chooses somewhere else: good lighting, visible cameras, clear signs, tidy fences and controlled entrances.
2. Detect
Know quickly that something is happening, and where: intrusion alarms, video analytics, door contacts and alert staff.
3. Delay
Slow the intruder down long enough for a response to arrive: solid doors and frames, good locks, fences, barriers and secure rooms.
4. Respond
Stop the threat, then recover and learn: guards, police, clear procedures and regular drills.
The key rule
Delay must last longer than the response takes. If help needs 10 minutes to arrive, your barriers must hold for more than 10 minutes after detection. Measure both, and design to close the gap.
Try the interactive layers of protection tool on this page to see example measures for each layer.