“ Addition (to an existing structure)” means any walled and roofed expansion to the perimeter of a structure in which the addition is connected by a common load-bearing wall other than a firewall. Examples of accessory structures are detached garages, carports, storage sheds, pole barns, and hay sheds. Accessory structures should constitute a minimal initial investment, may not be used for human habitation, and should be designed to have minimal flood damage potential. “ Accessory structure (appurtenant structure)” means a structure that is located on the same parcel of property as the principal structure and the use of which is incidental to the use of the principal structure. Mandatory flood insurance purchase requirements apply. No base flood elevations or depths are shown. Zone A99 may only be used when the flood protection system has reached specified statutory progress toward completion. These are areas of special flood hazard where enough progress has been made on the construction of a protection system, such as dikes, dams, and levees, to consider it complete for insurance rating purposes. Zone A99: Areas subject to inundation by the one percent annual chance flood event, but which will ultimately be protected upon completion of an under-construction Federal flood protection system. Zone AR: Areas that result from the decertification of a previously accredited flood protection system that is determined to be in the process of being restored to provide base flood protection.
Average flood depths derived from detailed hydraulic analyses are shown within this zone. Zone AH: Areas subject to inundation by one percent annual chance shallow flooding (usually areas of ponding) where average depths are between one and three feet. Zone AO: Areas subject to inundation by one percent annual chance shallow flooding (usually sheet flow on sloping terrain) where average depths are between one and three feet. (Zone AE is on new and revised maps in place of Zones A1 – A30.) Base flood elevations are shown within these zones. Zone AE and A1 – A30: Areas subject to inundation by the one percent annual chance flood event determined by detailed methods. Because detailed hydraulic analyses have not been performed, no base flood elevation or depths are shown. Zone A: Areas subject to inundation by the one percent annual chance flood event. These areas are labeled as Zone A, Zone AE, Zones A1 – A30, Zone AO, Zone AH, Zone AR and Zone A99 on a FIRM or FHBM. In A zones, floodwaters may move slowly or rapidly, but waves are usually not a significant threat to buildings.
“ A zone” means portions of the SFHA in which the principal source of flooding is runoff from rainfall, snowmelt, or a combination of both.