Disaster-Resistant Housing

Hazard Avoidance

Hazard avoidance is the practice of siting and construction to prevent or limit the hazard's interaction with a building. Avoiding the hazard first requires understanding how and where the hazard will affect a building. Hazard avoidance is most often seen for flood hazards, where elevation of housing above the 100-year flood level is standard practice for compliant buildings in communities that participate in the National Flood Insurance Program (NFIP). By elevating a building and its components above the level of flooding, damage and loss can be avoided or greatly minimized. In addition to meeting flood insurance requirements, constructing homes above potential floodwaters can alleviate the need for horizontal loading systems to resist water-based lateral forces above the elevated foundation. Additional examples of hazard avoidance include removing surrounding hazards (e.g., sick or dead trees, unanchored sheds, and abandoned vehicles) to minimize potential wind and flood damage to nearby structures and building structures at or below ground level to obtain inherent protection from tornadoes and lightning.

Hazard Resistance

Hazard resistance is the second method of disaster-resistant construction and is the practice of design, construction, and maintenance of building components and systems to resist the loads imposed by a hazard. Different hazards create loads that vary in origin and direction. Disaster-resistant housing must be appropriately designed and built to correctly respond to the specific loading encountered. One of the most important features of disaster-resistant housing is consideration of the magnitude and direction of forces that the building will experience. There must be assurance that these forces can be safely transferred to the ground, where they can dissipate. For example, earthquake loads originate at the ground and cause primarily lateral motions throughout the building, often resulting in significant displacement at the tops of tall structures. These loads must be transferred through the building members back to the foundation through a continuous load path. A continuous load path refers to the primary [Page 137]pathway through which loads are transferred; if there is discontinuity in the path or if a particular component along the pathway fails, then a failure in the building will result.

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