Cost effective hazard mitigation strategies for residential building in coastal regions

Hurricanes are among the most destructive disasters which impact residential structures in coastal communities. Coastal communities have historically experienced severe devastation from hurricanes and substantial economic and social losses have been attributed to damage from hurricanes. As a result, mitigation studies have been focused towards hurricane resistant structures in order to eliminate future damage.

The primary objective of this thesis is to study cost effective mitigation alternatives to residential foundations in coastal regions. A building's foundation is susceptible to failure from hurricane-induced loads including; wind, flood, and bearing pressure loss due to scouring. This study discusses the structural adequacy of coastal foundations and methods of implementing the most cost effective foundation system.

In order to prevent foundation failure from hurricanes, one needs to understand the different types of coastal foundations and identify which will perform best for a given location. Four types of coastal foundation are identified and discussed in this study: crawlspace, stem wall, grade beam, and pile foundation. Building codes and federal flood regulations relating to hurricane resistant design are identified and discussed. Finally, a quantity takeoff is prepared to determine the cost for various foundations.

This study finds the most economical foundation is a crawlspace when the foundation is not susceptible to wave load and soil scour. For coastal zones that are susceptible to wave loads but are not affected by scour, two options are available: 1) Pile foundation and 2) Grade beams. The most economical foundations in this circumstance vary with wind speed and elevation.

The choice of coastal foundation type may be based on lowest cost or on providing a personal preference, function, or aesthetic need at the site. However, government hazard mitigation grants are generally provided on the basis of cost reasonability, therefore, it is important to consider mitigation alternatives based on cost effectiveness. This study presents a cost estimate for coastal foundations utilizing a wide range of variables that include wind speed, elevation, and building geometry.