What is A Buoyant Foundation?
A buoyant foundation “is a type of amphibious foundation in which an existing structure is retrofitted to allow it to float as high as necessary during floods while remaining on the ground in normal conditions” (Buoyant Foundation Project). There are three elements:
1. buoyancy blocks that are installed under the house that will help float the building,
2. vertical guideposts that prevent the building from wondering during a flood beyond the vertical movement, and
3. a structural sub-frame that ties the blocks and guideposts together.
Case Study: New Orleans
Buoyant foundations are believed to be a possible solution for the extreme elevation of existing buildings. Consider New Orleans, a place known for its architecture, but equally well known for its susceptibility to flooding. To elevate above the FEMA recommended base flood elevation and retain flood insurance, some areas of New Orleans have to elevate twelve to fifteen feet to meet those standards. Not only does the extreme level of elevation cause issues for accessibility, but also destroys the neighborhood character, and puts the buildings at risk of a different threat: wind damage.
Elizabeth English, an Associate Professor at the University of Waterloo School of Architecture, presented on this very case at the conference Road Map Towards a Flood Resilient Urban Environment. This conference was sponsored by UNESCO and COST Action in 2009. The paper English presented was, “Amphibious Foundations and The Buoyant Foundation Project: Innovative Strategies For Flood-Resilient Housing.”
New Orleans is a historic community with a particular architecture that includes shotgun houses (image above). These houses are rectangular, typically one story. The relationship of the community and the houses are integral to the historic understanding of the historic districts. Elevating these buildings to extreme heights would disrupt the view that New Orleans is famous for. “A buoyant foundation is a relatively inexpensive, unobstructive retrofit to a shotgun house that provides it with buoyancy blocks and a verticle guidance system interconnected by a light structural frame, so that the house rises to float on the water when flooding occurs and settles back into its original place when the water recedes” (English, 3).
The idea of buoyant foundations is nothing new in New Orleans, according to English. “In rural areas of south Louisiana, there have been clusters of amphibious house functioning reliably for over thirty years” (English, 3). The experimentation with this adaptation method was allowed due to the lack of building codes and oversight in rural areas, allowing people to float their buildings with the ebb and flow of the mighty Mississippi and Gulf tides. There are hopes that approval for the technology can be granted to test in New Orleans parish.
More research is needed, and the application of this technology for historic buildings is still to be uncovered. However, climate change and sea level rise are issues that humanity has not dealt with to this extreme. It is imperative that research and innovation take place in order to respond to the climate crisis.
Let’s Take ACKtion!