Dry floodproofing a building involves sealing the portion of the building below the highest expected flood level to make it watertight and as impermeable to floodwaters as possible. In other words, the goal is to keep the water out of the building, which is achieved through a combination of sealant systems, like wall coatings and waterproofing compounds, and closing openings, such as doors and windows, with permanent or removable shields. Dry floodproofing is best suited for infrequent flooding and shorter duration floods.
One of the main advantages of dry floodproofing is that it is a minimal cost and minimal effort solution.
The main disadvantage of dry floodproofing is that it is a short-term solution and will, therefore, result in the deterioration of building materials due to repeated exposure to floodwaters.
- Some aspects of the building’s architecture will be modified, although these modifications are minimal.
- The floodwater on the exterior walls of the building can cause an immense amount of pressure (hydrostatic pressure). For this reason, dry floodproofing is not a good option for wood frame buildings or buildings with a basement.
- Maintaining the sealant systems is essential to the success of this flood protection option.
- Although the goal of dry floodproofing is to keep water out of the building, it is not a fail-safe system and water may enter the building due to sealant failures. Consequently, after flood events, there may be some clean-up costs and the building may need to be closed for an extended period of time.
- The exterior wall surfaces in the flood zone likely will be coated with waterproofing which will change the appearance.
- Southern Tier Central Regional Planning and Development Board, Floodproofing Info #4, www.stcplanning.org/usr/Program_Areas/Flood_Mitigation/Floodproofing/FProof_04_Dry_Floodproof.pdf