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Page 4 of 7 <br />City of Redwood City 1017 Middlefield Road, Redwood City, CA. 94063 Tel: 650-780-7000 www.redwoodcity.org <br />apply to the RH zone, where challenging topography may require wider frontages for adequate emergency <br />access. <br />Chapter 41, Floodplain Management <br />To update the minimum height above base flood elevation for the lowest floor elevation of construction <br />in all flood zones consistent with Building Code requirements and FEMA recommendations. <br />Section 41.18 <br />o Adds language to revise the lowest floor elevation to a minimum of one-foot above the <br />base flood elevation or the design flood elevation, whichever is higher, for Zone A and <br />all other zones <br />Both federal and state standards guide floodplain development. At the federal level, the National Flood <br />Insurance Program (NFIP), managed by FEMA, identifies and maps flood hazards, disseminates flood-risk <br />information through flood maps, and requires community land-use and building-code standards. <br />Communities that participate in the program, as Redwood City has since 1982, are required to regulate <br />development in a floodplain by adopting minimum standards. One such standard is that all new <br />construction and substantial improvements within Special Flood Hazard Areas (SFHAs) must have their <br />lowest finished floor at a height above the Base Flood Elevation (BFE) – the estimated height of floodwater <br />during a 100-year flood event. Both FEMA and NFIP recommend that communities adopt higher standards <br />to mitigate flood risk, such as providing additional freeboard1 that requires finished floors to be placed <br />higher above the BFE. <br />In April 2019, FEMA updated Flood Insurance Rate Maps (FIRMs) for the San Francisco Bay Area, including <br />Redwood City. These maps significantly changed the flood risk zone designation for much of downtown <br />Redwood City north of Broadway to Zone AE, a SFHA. Zone AE has a BFE of 10 feet. <br />At the state level, the California Code of Regulations Title 24 (CCR Title 24) contains the following <br />provisions for construction within SFHAs: <br />CCR Title 24 (Part 2.5) Residential Code Section R306.1: “Building and structures in flood hazard <br />areas… shall have the lowest floors elevated to or above the base flood plus one foot, or the <br />design flood elevation, whichever is higher.” CCR Title 24 (Part 2.5) applies to one- and two-family <br />dwellings, townhouses three stories or less, and accessory dwelling units. <br />CCR Title 24 (Part 2) Building Code, Appendix G, requires that all construction within a SFHA be <br />designed and constructed in accordance with ASCE 24: Flood Resistant Design and Construction, <br />a nationally recognized standard promoted by FEMA and the NFIP. ASCE 24 requires that lowest <br />floors within SFHAs be elevated to or above base flood plus one foot. <br />Amending the Municipal Code to require structures within SFHAs to have their lowest floor elevated to <br />base flood elevation plus one foot creates consistency between recommendations by FEMA and NFIP, <br />requirements by CCR 24, and the Municipal Code. <br />1 In this instance, freeboard is the vertical distance between the highest expected water surface elevation and the <br />finished floor elevation, serving as a safety buffer to mitigate flood waters entering the structure. <br />8.A. - Page 4 of 24 <br />143