Summary. Table 41 summarizes the maximum penetration delay times
achieved by floor/roof construction in use today. These times are for the
high-level threat. It is not practical to attack these barriers at the
low-or medium-level threats. Concrete floors can provide up to about 45
minutes of delay against the high-level threat whereas concrete roofs only
provide about 35 minutes. Wood construction provides up to 1.5 minutes
against high- level threats and 1.6 minutes against medium-level threats.
Metal construction can provide up to about 2 minutes of delay for roofs but
up to 15 minutes for floors that use riveted steel gratings.
18.104.22.168. Low-Security Threat Level. As noted, it is not practical to attack
roofs/floors with a limited set of hand-held tools. A more reasonable attack
would be against more vulnerable parts of the facility such as doors,