New Roof/Floor Construction for Low- to High-Severity Threats
Summary. Only conventional or steel-fiber-reinforced concrete
construction are recommended for the medium- and high-severity threat levels.
Any construction can be used for low-severity threats. Other types of
roof/floor construction such as wood frame or metal provide only nominal
protection (typically less than 2 minutes) and are not recommended for the
medium and high threat levels.
Low-Severity Threat Level. In general, it is not practical to
attack roofs or floors using only a limited set of low-observable, hand-held
tools. A low level threat more likely would attack the doors, windows, or
other more vulnerable part of the facility. Consequently, any roof or floor
construction can be considered adequate for this threat level.
Medium- and High-Severity Threat Levels. Conventional or steel-
fiber-reinforced concrete construction options and corresponding minimum
penetration times for medium- and high-severity threat levels are summarized
in Figures 33 and 34 and Table 22 for a downward attack on roofs or floors.
Figure 35 with Table 23 presents data for an upward high-severity attack on
the floor. Figure 35 does not include medium-severity attacks because it is