CMU walls provide pedestrian access through commercial hollow steel doors.
In such a facility the barrier value of the basic structure, while designed
to be relatively high, is weakened by the use of ordinary doors, frames, and
hinges. Balanced design dictates the use of doors that provide the delay
times commensurate with the structure in which they are installed.
The number of doors to a facility should be reduced to an absolute
minimum. In cases where more than one door exists, only one of these should
be provided with outside-mounted locks and entry hardware. All others
should, as far as practicable, present blank, flush surfaces to the outside
to reduce their vulnerability to attack. Exposed locking devices on the
exterior (attack side) of the door should be used only on low- or
medium-security applications. No matter how secure a door is made, placing
the locking device on the exterior of the door cannot provide the level of
security required for high-security applications.
Although the penetration time through the door surface usually can
be increased by use of heavier or composite materials, such hardening may not
provide a complete security solution because of weight constraints, conflicts
with functional requirements, mounting hardware limitations, or lock
vulnerability. There is no point in hardening a door surface beyond the
attack resistance of the available mounting hardware and locking device
technology. According to available data, currently used standard or
commercial door or door hardware do not provide significant penetration time
against a determined intruder.
For example, personnel doors currently are available only for the
low- and medium-severity threat levels. Although vehicle doors are available
for the low through high threat levels, they provide only nominal penetration
times of 1 minute or less. Vault doors are designed for the medium- and
high-severity threats and AA&E magazine doors are used for the very
high-severity threat. Commercial door manufacturers provide attack- and
bullet-resistant doors. When properly installed, these doors may offer a
substantial increase in penetration resistance over standard industrial
doors. Requirements for each type of door are described in the following
Personnel Doors. As shown in Table 24, personnel doors are
available for low- and medium-severity threat levels. There are no personnel
doors available to defeat the high- and very high-severity threat level.
Potential attack areas on doors include the face (surface), hinges, and
Low-Severity Threat. Door design for the low-severity threat
is summarized in Tables 25, 26, and 27.