ASFPM CFM key terms

Land shown on a Flood Insurance Rate Map as having a 1% or greater chance of flooding in any given year. It is the area where NFIP insurance purchase requirements and local floodplain development rules apply.

The flood that has a 1% chance of being equaled or exceeded in any single year, often called the 100-year flood. It is the national benchmark for regulating development and identifying insurance zones.

The height that the base flood reaches at a given location, usually stated in feet above a named vertical datum such as NAVD88. It anchors elevation requirements, insurance rating, and mapping.

The official map a community adopts for floodplain regulation. It shows special flood hazard areas, flood zones, base flood elevations in detailed study areas, and the panel boundaries of the mapped area.

The engineering report published with a FIRM. It documents the hydrologic and hydraulic analyses, flood profiles, base flood elevations, and methods used to identify the flood hazard.

The river channel plus adjacent land that must remain unobstructed so the base flood can pass through without raising flood heights more than a set amount, usually one foot.

A FEMA determination that amends or revises the effective flood map without a full map reprinting. Common forms include LOMAs, LOMR-Fs, and LOMRs used to add or remove property from the SFHA.

FEMA's written comment on whether a proposed project, if constructed as described, would be consistent with floodplain mapping and whether a later map revision would likely be approved.

The SFHA along open coastlines subject to high-velocity wave action, mapped as V or VE zones. Construction there must be elevated on open pile foundations with no obstruction below the lowest floor.

A margin of safety, measured in feet, by which a building's lowest floor or floodproofing level is placed above the base flood elevation. It is often required locally and rewarded in insurance rating.

The elevation to which a structure must be built under a community's ordinance or a program's standards. It is typically the base flood elevation plus any required freeboard or locally adopted higher standard.

The lowest enclosed floor of a building, including a basement but excluding qualifying crawlspaces and enclosure areas built to flood-resistant standards. It is the reference point for elevation compliance and insurance rating.

A FEMA form completed by a licensed surveyor or engineer that records a building's elevations, flood zone, and construction type. It is used to verify compliance and to rate flood insurance policies.

Measures that make a building or its utilities resistant to flood damage. Dry floodproofing uses watertight barriers to keep water out; wet floodproofing lets water enter non-living spaces to equalize pressure.

Required openings, commonly hydrostatic vents, in the walls of enclosed areas below the lowest floor. They let floodwater flow in and out so pressure equalizes and structural damage is reduced.

Any reconstruction, rehabilitation, or addition to a building whose cost equals or exceeds half of the building's market value before work starts. It triggers full compliance with current floodplain standards.

Damage from any cause that equals or exceeds half of a building's pre-damage market value. When repairs follow, the community must enforce current floodplain requirements on the building.

A local ordinance provision that adds together the cost of improvements made over a set period, often five or ten years, to decide whether the substantial improvement threshold has been reached.

Documentation from a licensed engineer showing that a proposed encroachment in the regulatory floodway will not increase base flood elevations. Communities must obtain it before issuing a permit for the work.

Any development, fill, or structure placed in a floodplain or floodway that may obstruct flow, raise flood heights, or otherwise alter the flood hazard, making it subject to permit review.

A scheduled or unannounced review in which FEMA or the state checks whether a participating community is enforcing its floodplain ordinance, and offers technical help before problems escalate into sanctions.

A formal NFIP sanction placing a community with serious compliance deficiencies on probation. It can add a surcharge to policyholders' premiums and may lead to suspension if problems are not corrected.

Removal of a community from the NFIP for failing to adopt or enforce compliant floodplain regulations. Afterward no new flood insurance can be sold there and certain federal assistance may be restricted.

A local government that has adopted a FEMA-approved floodplain management ordinance and joined the NFIP, which makes federally backed flood insurance available to property owners within its boundaries.

The full phase of NFIP participation that begins once FEMA provides the community with a Flood Insurance Rate Map, offering higher coverage limits and more detailed floodplain management requirements.

A voluntary NFIP program that grants flood insurance premium discounts to policyholders in communities exceeding minimum standards through outreach, mapping, open space preservation, and drainage maintenance activities.

Up to $30,000 in additional NFIP claim money available to help pay for elevating, relocating, demolishing, or floodproofing a building that is substantially damaged or repeatedly flooded.

A building constructed or substantially improved before the community's first effective Flood Insurance Rate Map date. Such buildings are rated differently and often carry lower, historically subsidized premiums.

A building constructed or substantially improved on or after the community's initial Flood Insurance Rate Map effective date, rated using the flood zone and elevation information that applied when it was built.

NFIP rating rules that allow a policyholder to keep the zone or elevation basis that applied when the building was constructed or an earlier policy was written, even after flood maps are updated.

A property that has received two or more NFIP claim payments of more than $1,000 each within any ten-year period, making it a priority for mitigation outreach and compliance actions.

A property with four or more NFIP payments over $5,000, or at least two payments together exceeding its value. These properties carry specific mitigation planning and disclosure obligations.

FEMA's current NFIP pricing approach, which sets premiums from modeled risk factors such as distance to water, flood frequency, building traits, and replacement cost instead of flood zone alone.

A principle holding that a development action should not increase flood risk, flood heights, or damage potential for other properties or the environment, going beyond minimum regulatory standards.

A jurisdiction's plan identifying local risks, vulnerable assets, and cost-effective actions to reduce future disaster losses. It must be updated periodically to keep certain federal mitigation funding available.

FEMA funding made available after a presidential disaster declaration to help states and communities carry out long-term measures that reduce losses from future disasters.

A mitigation strategy in which flood-prone buildings are purchased, usually at pre-disaster market value, then demolished or moved, with the land kept as open space through a permanent deed restriction.