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## Structural Problems of Buildings Under Construction and Renovation A building in which work is in progress is often more prone to structural failure and collapse than it would be in its completed, occupied state. This is due to a number of factors, including the lack of floors or roofs. A compl...

## Structural Problems of Buildings Under Construction and Renovation A building in which work is in progress is often more prone to structural failure and collapse than it would be in its completed, occupied state. This is due to a number of factors, including the lack of floors or roofs. A completed structure relies on each of its major structural components to brace and support the others. A wall that is carrying a load (a bearing wall) is more stable than a wall with no load (a free-standing wall). This is because of the downward compression on the wall as well as the horizontal bracing provided by the floor and the roof. Structures that are missing all or parts of their floors or roofs may be unstable even without being exposed to fire. When fireproof coatings or membranes are missing, steel may be exposed to rapid rises in temperature, which can lead to failure. Steel I-beams and columns often receive a spray-on fibrous coating that protects them from this heat. This coating is often damaged or removed during later construction operations, especially alterations, and is rarely repaired. If this coating is missing, the steel will lose strength at approximately 1,500°F. Often many so-called noncombustible buildings rely on a hung ceiling to provide a membrane-type fire resistance between the occupancy and the otherwise unprotected steel. The hung ceiling tiles often aren’t installed until much of the rest of the construction has been completed and the occupants have begun moving in. The photo shows a partially finished building interior. The ceiling consists of suspended tiles. The photo shows the exposed steel beams and the unfinished drywall.