Perimeter protection: detecting before they get in

The layers

1. The property boundary: fence, gate, vehicle entrance.
2. The garden or yard: the area between the boundary and the house.
3. The envelope: doors, windows, shutters.
4. The interior.

The earlier the detection, the more time there is to react.

What's used

• Contacts and sensors on doors and windows: detect opening or impact. They let you sleep with the alarm armed.
• Outdoor motion detectors: built for the weather, with dual technology to tell a person from a branch or an animal.
• Curtain detectors: create a narrow detection strip along a façade or large window.
• Infrared beams: a beam between two posts, for straight boundaries.
• Cameras with analytics: detect people or vehicles crossing a line or entering a zone, and send the image.

Deterrence

• Lighting that comes on when movement is detected.
• An outdoor siren or loudspeaker warning.
• Visible cameras and signs.
• Presence simulation when the house is empty.

Avoiding false alarms

This is the big challenge outdoors. What helps:

• Detectors designed for outdoor use, not repurposed indoor ones.
• Adjusting height, angle and range so they don't see the street or the neighbour.
• Keeping vegetation trimmed in front of detectors.
• Video verification: the alert arrives with a photo or clip, and you decide in seconds whether it's real.
• Zone crossing: only raising the alarm when two detectors trigger in sequence.

With pets and the family at home

The perimeter can be armed while the family is inside or the dog is in the garden, if the design allows for it: zones, detection heights and schedules.

In a mountain climate

Snow build-up, fog, wildlife and sharp temperature swings all affect outdoor detectors. Choice of equipment, mounting height and maintenance after winter matter more than in other climates.

Privacy

Cameras should be limited to your own property. Capturing the public street or a neighbour's land more than strictly necessary can breach data protection law.

In businesses

For warehouses, shops and car parks, the perimeter is combined with vehicle access control and schedules: what is normal traffic by day is an alert at night.