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# Figure 22-31 This explosion blew out the left side wall of the right four-story brick building, landing on the left building. * The second-floor joists fell all the way to the first floor on the left side, while the right side remained partially attached, creating a supported lean-to void that ra...

# Figure 22-31 This explosion blew out the left side wall of the right four-story brick building, landing on the left building. * The second-floor joists fell all the way to the first floor on the left side, while the right side remained partially attached, creating a supported lean-to void that ran the entire length of the store behind the roll down gate. # Unsupported Lean-to Collapses Unsupported lean-to collapses result from similar events that cause the supported lean-to, but the floor or roof joists end up dangling in midair, held only by their attachment at the remaining standing wall. # Figure 22-33 The low end is totally unsupported, creating a severe danger of further collapse. Search of the voids under these overhanging floors is extremely dangerous and should be carefully monitored for safety. * At times, the only safe way to operate under this overhanging debris is to pull it down so it doesn't fall on rescuers. * This should only be done after surface victims have been removed, voids have been searched, and you are reasonably sure that no other survivors will be hurt by the falling debris.