Slab moisture matters more than the flood map here
A garage or interior coating is one of the few trades where the flood map is largely background. What governs the outcome is moisture moving up through the slab, which on this low, sandy peninsula is common and is not visible before grinding. Flood zone becomes relevant only where a property has taken water before and the slab was never properly dried.
Official sources
Test the slab rather than trusting the map
Citywide flood mapping cannot tell you the moisture content of your slab, what previous coating is bonded to it, or whether a prior flood left contamination in the concrete. A moisture test before quoting is worth more here than any map.
Research date
Sources reviewed June 22, 2026. Flood maps and local requirements get updated outside this site's control.