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"Substantial Damage" - What Does It Mean?

Monday November 22, 2021 02:44 pm


Terrebonne Parish

Department of Planning and Zoning

Recovery Assistance and Mitigation Planning

FloodSafe Minute

Substantial Damage” – What Does It Mean?

Inspectors have been collecting data from around the parish, and in the next several weeks, more inspectors will be in the community taking pictures of damaged structures to determine if they are substantially damaged. Substantial damage applies to a structure in a Special Flood Hazard Area (SFHA) – or a1-percent-annual-chance floodplain – for which the total cost of repairs is 50 percent or more of the structure’s market value before the disaster occurred, regardless of the cause of damage.  The Floodplain Administrator will review the substantial damage estimations from the inspectors and inform those structure owners that have a substantially damaged structure of their options. That information helps property owners decide whether to, or how to, repair or replace a damaged dwelling.

If a building in a floodplain is determined by the local official to be substantially damaged, it must be brought into compliance with local floodplain management regulations.

Owners may decide to:

  • Elevate their structures, or change them in some other way to comply with those local floodplain regulations and avoid future losses;
  • Relocate or demolish the structure; or,
  • Flood proof a non-residential structure.

Substantial damage applies to a structure in the regulatory floodplain determined by FEMA for which the total cost of repairs is 50 percent or more of the structure’s market value before the disaster occurred, regardless of the cause of damage.  Terrebonne Parish has a cumulative substantial damage standard, so this is added to all damages repaired or improvements to the structure in the past 10 years

For example, if a structure’s market value before the damage was $200,000 and repairs are estimated to cost $120,000, that structure is substantially damaged. Land value is excluded from the determination.

All property owners should check with the permits department at 873-6567 to determine which permits for repairs are required before beginning any repair work. A substantially damaged structure can’t be permitted for repairs unless there are provisions for compliance with the Flood Damage Prevention Ordinance. This means that the structure must be or be brought to or above the FEMA base flood elevation.  Again, this is damage from wind, fire, or any cause and not only flood.

The decision about a structure being “substantially damaged” is made at the local government level based on the Flood Damage Prevention Ordinance required by FEMA in order to have flood insurance available through the National Flood Insurance Program.  In Terrebonne Parish, the Floodplain Administrator makes the final determination and advises the structure owner.  

Exception: Structures built after the 2006 adoption of the current flood plain maps will not be inspected as these structures will all meet the base flood elevation.

If the storm damage from Hurricane Ida was from flood, property owners who have a flood insurance policy through the NFIP and a substantially damaged building (from flooding) in a SFHA may be able to use additional funds – known as Increased Cost of Compliance (ICC) – from their flood insurance policy (up to $30,000) to help defray the costs of elevating, relocating, demolishing a structure, or flood proofing a non-residential structure.

For more information on ICC, contact your insurance agent. 

Desire Line, LLC and Parish employees will be making inspections through the Parish, taking pictures and notes.  Do not be alarmed.  They are there at the request of the Parish to comply with Title 44 Code of Federal Regulations [CFR] Section (§) 60.3.  Call 985-873-6567 with any questions or concerns. 

You can email to request information in a language other than English.

Information also is available at and

Adapted from FEMA document R4 DR-4338-GA FS 008 October 6, 2017