Substantial Improvements and Damage

Per Middletown Ordinance No. 2022-3346, Section 103.14, the Floodplain Manager monitors the costs of permitted work on homes in the regulated flood zone as a condition to participate in the NFIP.

The floodplain manager must determine whether proposed work qualifies as a Substantial Improvement or repair of Substantial Damage (SI/SD determination). If work on buildings constitutes an SI/SD, then structures must be brought into compliance with all local codes and NFIP requirements for new construction, including the requirement that lowest floors be elevated to or above the local Design Flood Elevation, which is FEMA BFE +1 additional foot of freeboard.

The NFIP defines an SI/SD as follows:  

Substantial improvement (SI) means any reconstruction, rehabilitation, addition, or other improvement of a structure, the cost of which equals or exceeds 50 percent of the market value of the structure (or smaller percentage if established by the community) before the “start of construction” of the improvement. This term includes structures that have incurred “substantial damage,” regardless of the actual repair work performed. 

If you are looking to renovate, rehab, or build an addition to a home in the floodzone, our SI Determination Form (PDF) is required to be submitted to the Floodplain Manager. Please note the requirement on page 2 in red; this is critical for us to maintain compliance with NJDEP and FEMA regulations. You can email it to

Substantial damage (SD) 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. Work on structures that are determined to be substantially damaged is considered to be substantial improvement, regardless of the actual repair work performed.

In Middletown, home improvements are calculated over a 10-year period as of the adoption of our latest Flood Hazard Ordinance in June 2022. This means all project costs collected at the time of permitting are entered into our system and tabulated over 10 years. If at any point during this time frame the value of home improvements meets or exceeds 50% of the home’s latest assessed value, the home will have to be brought up to code, including being elevated. Tax assessments can be found here.

Refer to FEMA’s Coastal Construction Manual for construction and design practices in coastal communities.