3.1.2. Dry Flood-Proofing

Dry flood-proofing techniques are designed to prevent floodwater from entering a building. Measures include the protection of doors and other openings with permanent or removable flood shields [16] by sealing walls with waterproof coatings, impermeable membranes or supplemental layers of masonry or concrete. Dry flood-proofing has disadvantages: When a house is surrounded by water, the pressure on the walls may cause them to cave in—especially in frame constructions. Both the Federal Emergency Management Agency (FEMA) [25] and Keating et al. [26], therefore, advise to not build dry flood-proof houses when floodwater heights exceed +1 m. Construction costs (Table 2) vary between ~\$9000 and \$23,000/building in developed countries, and between ~\$500 and \$10,000 per building in developing countries [18]. Costs depend on the type of measure and the flood depth they are designed to withstand. Wright and Pierce [33] calculate the cost for flood-proofing seven waste-water pumping stations that lie below the expected flood elevation. The average cost for each station is ~\$45,000, of which 59% is for "miscellaneous items" (e.g., overhead costs and 20% contingencies). Maintenance costs per year are estimated at 1–3% of the investment cost [26].

**Table 2.** Cost of dry flood-proofing buildings. The column "measure" shows for which water level measures are designed.


1 Values calculated using the 2016 consumer price index (CPI); 2 P = peer-reviewed; n.a. = not available; O&M: operation and maintenance costs.
