*3.1. Flood-Proofing and Elevating Buildings*

Three types of measures are commonly used to flood-proof individual buildings: (1) elevation of (new or existing) buildings, (2) dry flood-proofing, and (3) wet flood-proofing [25] (Appendix A Table A1). The lifespan of both wet and dry flood-proofing is estimated at 20–30 years [26], though Kreibich et al. [27] mention a lifespan of 75 years. In some countries, such as the United States, these measures are linked to building code guidelines provided by the state or municipalities. Building-code requirements apply for buildings in designated flood zones (e.g., the 1/100 flood zone), which are mapped by the government. Furthermore, building codes are often linked to an insurance system in which policy holders ge<sup>t</sup> a discount on their flood insurance premiums, when they implement flood-proofing measures. In the United States, the National Flood Insurance Program (NFIP) requires homeowners who have a state-backed mortgage to purchase flood insurance, and the base floor of new structures must be raised above the expected 1/100 flood levels [28].
