Flooding is a significant problem for buildings all around the world, including architectural treasures like the Farnsworth House that have been plagued by the issue time and time again. In particular, one-third of the entire continental U.S. are at risk of flooding this spring, especially the Northern Plains, Upper Midwest, and Deep South. Last April, deadly floods decimated parts of Mozambique, Malawi, Zimbabwe, and Iran as well, resulting in a low estimate of 1,000 deaths while tens of thousands more were displaced. While architecture cannot solve or even fully protect from the most deadly floods, it is possible – and necessary – to take several protective measures that could mitigate damage and consequently save lives.
The first step to take to this end is to identify whether the home or building being designed is in an area at risk for flooding. This can be done by checking flood maps widely available online, including this site run by the U.S. Federal Emergency Management Agency. If it is, the architect and client can decide if they want to relocate or if they would like to stay and take the necessary protective measures. For those who choose the latter, we have delineated nine such measures below.
Elevate Above the Flood Level
To start, architects should build the structure above the flood level to minimize damage if a flood does occur. The flood level elevation for specific areas can be found online using programs such as the Estimated Base Flood Elevation Viewer run by FEMA. With this information, architects can discern how high to raise the building and with what method they should do so. One common way of elevating is by building the structure on columns or stilts. In other cases, the solid foundation can simply be raised higher. For more specific information on what to do, architects should assess the climate and flood history of their area and consult information available online such as this manual on coastal construction in particular.
Build with Flood Resistant Material
Flood resistant materials are those which can last in contact with flood waters for at least 72 hours without significant damage. Flood water can be both hydrostatic (standing water) and hydrodynamic (flowing water), and in most cases will result in displaced foundation walls, collapsed structures, floating fuel tanks, scouring, and more. ‘Significant damage’ suggests any damage requiring more work that cleaning or low-cost cosmetic repair, such as painting. To prevent these damages, flood resistant materials must be durable and resistant to excessive humidity. Examples include concrete, glazed brick, closed-cell and foam insulation, steel hardware, pressure-treated and marine-grade plywood, ceramic tile, water-resistant glue, polyester epoxy paint, and more.
Apply Coatings, Sealants, and Waterproof Veneer
There exist two different types of floodproofing: dry and wet. Dry floodproofing prevents the entry of flood waters, whereas wet floodproofing allows flood waters to enter the house. Coatings, sealants, and waterproof veneer belong to the former, as they prevent water from reaching the interior. A waterproof veneer can consist of a layer of brick backed up by a waterproof membrane, sealing the exterior walls against water penetration. In the interior walls, architects should use washable closed-cell foam insulation in areas below the flood level. Similarly, coatings and sealants may be applied to the foundation, walls, windows, and doorways to prevent flood water from entering the house through cracks, as these openings are rarely designed to be watertight or resist flood loads as they are.