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Chapter 6

Physical Barriers

Effective Physical Security

Fourth Edition

The University of Adelaide, School of Computer Science

Chapter 2 — Instructions: Language of the Computer

Physical Barriers

Physical barriers used since before Roman Empire
Roman garrisons
Fortresses in Revolutionary War
Army forts in Indian territories
Base camps in war zones
Improved concept of physical barriers over the years

6 Physical Barriers

The University of Adelaide, School of Computer Science

Chapter 2 — Instructions: Language of the Computer

Doors

Function is to provide a barrier at entry/exit
In maximum security, provides barrier but:
Must be impenetrable by ordinary means
Maximum delay time by extraordinary means
In building maximum security facility, must define function of all doors and relationship to total protection system

Doors—Personnel

Average industrial personnel door:
Hollow steel composite door with 18-gauge metal facing
Butt hinges with nonremovable pins
Opens in either direction
May have ventilation louvers or glass panels

Doors—Personnel

Can be penetrated in 1 minute or less by:
Breaking locking mechanism with pipe wrench
Pry bar to pry door open
Using a fire axe to penetrate the door

To make more resistant:
Bolting or welding steel plate
Install several dead bolts
Welding steel louvers on inside
Replace or upgrade hardware with more resistant ones

Doors—Personnel

Substantial steel or security class doors:
¾-inch steel on one side, 1/8-in steel on other
Ready-made security panels (DELIGNIT®)
Highly-tempered plate material (hardwood veneers, cross-laminated, bonded with phenolic resins
Thicknesses of 20, 30, 40, and 50 mm

Doors—Personnel

Frames should be anchored to the wall to make it penetration-resistant
Hinges should be inaccessible from side of door facing the likely threat or
Individual hinges should be case hardened or replaced with heavy-duty hinges and pins

Doors—Personnel

<Insert Figure 6-2>

Doors—Personnel

Other protection methods:
Consider installing ¼-inch steel plates over exposed hinges
Mortise hinges into door jamb and door
Install piano hinge on outside of door

Doors—Personnel

Dead bolt principle:
Install ½-inch steel rods equidistant between support hinges on inside of door
Install ¼-inch steel plate on inside of door jamb

Doors—Personnel

Existing door can be hardened by welding heavy angle iron or an I-beam to form a grid on inside of front door panel.
Doors should open toward likely threat direction
Consider turnstile-type doors.

Retrofit Upgrading of Existing Doors

To harden an existing door against tool attack:
Customary—clad with heavy-gauge sheet metal or steel plate
Can be implemented quickly with local materials
Only to solid or laminated wood, substantial hollow metal doors

Retrofit Upgrading of Existing Doors

Thinnest recommended material
12-gauge sheet metal
Should be securely fastened using carriage bolts
Nuts from the protected side and no less than 5/16 inches in diameter
As close to edge of door frame as possible

Retrofit Upgrading of Existing Doors

If cladding applied to outward-opening door:
Provide protection to free edge
Wrap sheet metal cover around door edges

Retrofit Upgrading of Existing Doors

Take into account:
Effects of door fit due to additional thickness
Problems of additional weight
Provide for mounting with heavy-duty hinges
Protect against hinge-pin removal and hinge destruction

Retrofit Upgrading of Existing Doors

Recommended door:
Hollow door with skin of 12-gauge cold-rolled steel reinforced by:
Internal channel stiffeners of 22-gauge or thicker steel
Can fill hollow spaces for thermal insulation

Door Frames

For full resistance to attack:
Harden frame and attachments like door.
Fabricate frame of at least 16-gauge steel.
Fill with cement grouting.
Bond to wall structure surrounding the door system.

Hinge Vulnerability

Hinge on exterior frame vulnerable to:
Drive out hinge pin with drift punch/hammer
Cut off with hacksaw, cold chisel, torch
To inhibit/prevent removal of hinge pins:
Peening over or tack-welding ends of pins
Install set screw in knuckle.
Use a continuously interlocking hinge system.

Door and Frame Interlocking

Countermeasures to prevent destruction or removal or hinge pin/knuckle assembly:
Install substantial protruding steel dowel pin in hinge edge of door or frame with a mating socket or hole in frame or door
Pin engages in socket when door is closed
Door/frame automatically interlock when closed

Door and Frame Interlocking

A variety of devices:
Pin-in-socket
Tongue-in-grove
Large fabricated steel doors:
Orient channel-iron framing member to create a cavity where a corresponding angle iron can engage