If an effective FEMA flood map appears to include a property, first confirm the map panel, parcel, and exact building or land area at issue. FEMA has different map-change paths for natural ground, fill, completed changes to a community map, and a proposed project. A map-change decision addresses its stated subject; it does not approve an ADU or replace local floodplain requirements.

Match the request to the ground condition or project stage

  • A Letter of Map Amendment (LOMA) is the property-specific route described for a building or land on natural ground that appears in a Special Flood Hazard Area but may qualify for removal based on elevation information.
  • A Letter of Map Revision Based on Fill (LOMR-F) concerns land or a structure elevated by fill. FEMA’s guide identifies community acknowledgement and applicable survey or elevation information among the request materials.
  • A Letter of Map Revision (LOMR) revises an effective National Flood Insurance Program map to reflect changes such as floodplain, regulatory floodway, or flood-elevation information.
  • A Conditional Letter of Map Revision (CLOMR) is FEMA’s review of whether a proposed project or hydrologic change, if carried out as proposed, would meet minimum NFIP standards. It is conditional and comes before construction; it is not the completed map revision.

These labels are not interchangeable. State the requested subject precisely—a building, lot, or part of a property—and have the responsible survey or engineering professional determine which evidence and request type fit the facts. FEMA’s LOMA/LOMR-F guide is dated January 2022, so confirm current forms, fees, submission routes, and technical criteria before filing.

Keep the map decision separate from construction approval

A FEMA determination does not establish that the site is safe from flooding, remove every local floodplain rule, or authorize proposed construction. A CLOMR does not guarantee a final map revision after a project is built. Check the current effective map, the local floodplain administrator’s requirements, any community review or comment process, and the separate planning, building, and environmental approvals for the ADU.

Keep the effective panel and date, parcel or survey, requested subject, elevation information, FEMA correspondence, and local authority response together. If a boundary or map result is uncertain, ask the community floodplain administrator and a qualified professional what record resolves it. For screening and site-assessment steps beyond a map amendment, see how to check flood, conservation, wetland, and hazard constraints.

No map-change eligibility or outcome can be determined without a specific property, effective map, ground condition, and supporting records.