Water is Our Friend: Amphibious Foundations for Flood Resilience without Relocation

Amphibious retrofit construction is a flood risk reduction and climate change adaptation strategy that works in synchrony with a flood-prone region’s natural cycles of flooding. An amphibious foundation retains a home’s connection to the ground by resting firmly on the earth under usual circumstances, yet it allows a building to float up as high as necessary when flooding occurs, with a vertical guidance system that provides resistance to lateral forces. Unlike houses elevated at a fixed level, amphibious houses can easily accommodate varying levels of flooding. Amphibious foundations are a cost-effective, resident-friendly alternative to permanent static elevation (PSE) for housing in areas where rising flood waters are not accompanied by waves or high-velocity currents. Amphibious construction offers significant economic benefits in comparison to PSE. Detailed cost comparisons show that amphibious retrofits on average range from 1/4 to 1/3 of the cost of PSE. Loss Avoidance Ratio (LAR) studies for amphibious retrofits in two North American locations (Louisiana and Manitoba) provided average LARs of 2.1 and 5.7, respectively, demonstrating the potential for cost savings by implementing amphibious retrofits in these locations. Also, PSE increases a building’s vulnerability to wind. A collaborative study with colleagues at LSU determined that elevating the floor level of a home from 4 ft to 22 ft by implementing PSE creates a 75% increase in Expected Annual Loss due to increased wind damage. Amphibious buildings, as they remain close to the earth’s surface during windstorms, do not experience this increased exposure to wind and resulting losses. When applied as a retrofit to an existing structure, this approach can be implemented in a manner that complies with all current FEMA requirements. This presentation will define types of amphibious construction, show examples of both new-build and retrofit applications, discuss the benefits of, drawbacks of, and impediments to amphibious construction, and present case studies of designed and implemented amphibious foundations.

ABOUT OUR SPEAKER

Dr. Elizabeth English is Professor Emerita at the University of Waterloo in Ontario, Canada, where she has taught Architecture for the last twenty years, while every year spending at least Christmas to Crawfish Festival at her permanent home in Breaux Bridge. She is the founder and director of the Buoyant Foundation Project (BFP), a not-for-profit research organization that is developing amphibious foundation systems as a low-cost, low-environmental-impact flood-risk reduction and climate-adaptation strategy that supports the preservation of traditional housing forms and local cultural practices. She was Associate Professor-Research at the LSU Hurricane Center at the time of Hurricanes Katrina and Rita, which inspired her shift in research focus from wind to flood. Her work now focuses on flood-endangered marginalized communities, especially Indigenous communities, and on how amphibious construction can prevent flood damage, promote adaptation to climate change, and contribute to environmental justice and social equity. Her education, practice, teaching and research are interdisciplinary, with degrees in Architecture from Princeton (BA) and Penn (PhD) and in Civil Engineering from MIT (MSc). She is internationally recognized as a pioneer in the developing field of amphibious construction, with particular focus on retrofit applications to existing homes. The BFP website is www.buoyantfoundation.org.