Substantial damage / improvement

Enforcing the requirements that define whether a property is “substantially improved (SI)” or “substantially damaged (SD)" is a very important part of a community’s floodplain management responsibilities.

What is substantial damage?

Substantial damage means damage of any origin sustained by a structure whereby the cost of restoring the structure to its before damaged condition would equal or exceed 50 percent of the market value of the structure before the damage occurred.

Those structures identified as substantially damaged (more than 50% of the pre-flood market value) should be “red-tagged”.  Permits should not be issued until the structure is brought into compliance with floodplain regulations.  Those with less than 50% damage can be issued permits to repair.

What is substantial improvement?

Substantial improvement is any reconstruction, rehabilitation, addition or other improvement to a building, the total cost of which equals or exceeds 50 percent of the market value of the structure before the start of construction of the improvement. Most ordinances calculate improvements cumulatively; check your local ordinance for your specific requirements.

More information on substantial improvements and substantial damage can be found on the FEMA website:  Substantial Damage Estimator (SDE) Tool