The short answer
If your home is in a flood hazard area and does not meet today’s flood requirements, your city or county compares the cost of a remodel with the market value of the building, not the land. When the cost equals or exceeds 50 percent of that value, the project is a substantial improvement, and the whole building has to be brought up to current flood requirements. For a house, that chiefly means raising the lowest floor to the required flood elevation.
A home that already meets current flood requirements is generally not subject to the rule. For a home that does not, the questions are how much the building is worth for this purpose and how much the whole project will cost.
This guide covers how the rule works for interior remodeling, such as kitchens and bathrooms, in the Southwest Florida communities we serve.
The rule
The rule comes from the National Flood Insurance Program. Federal regulations define a substantial improvement as “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 before the ‘start of construction’ of the improvement.”
Remodeling counts even when the outside of the house does not change. FEMA’s desk reference for local officials lists “rehabilitation or remodeling of a building with or without modifying its external dimensions” among the work that can trigger the rule.
When a project is a substantial improvement, the building must comply with the flood requirements for new construction. For homes, the federal minimum is a lowest floor at or above the base flood elevation. Lee County, Collier County, Charlotte County, and the City of Punta Gorda state the requirement as the base flood elevation plus one foot.
The same 50 percent test applies to repairs. A building is substantially damaged when the cost of restoring it to its condition before the damage would equal or exceed 50 percent of its market value, whatever caused the damage.
Your home
That is land with a 1 percent or greater chance of flooding in any given year, shown on FEMA’s flood maps. You can look up an address at FEMA’s Flood Map Service Center, and several local governments offer their own lookup.
Lee County puts it this way: if your building is already flood compliant, the 50% rule generally does not apply. Charlotte County says a building whose lowest floor and equipment sit above the required elevation is considered compliant, and that an elevation certificate is required to show it.
The federal definition excludes alterations to a historic structure, provided the work does not cost the building its historic designation.
The test uses the value of the building. In Cape Coral, the property appraiser’s building value is not available for condominiums, so the city asks for an appraisal instead.
The value
Only the building counts. FEMA’s guidance says the value of the land, landscaping, driveways, and detached structures is not included, so the number is lower than what the property would sell for.
Florida’s model definition gives two ways to arrive at it: the actual cash value determined by a qualified independent appraiser, or the tax assessment value adjusted to approximate market value. Local governments here generally start with the county property appraiser’s value for the building and accept an appraisal from a Florida-licensed appraiser if you disagree with it.
The details differ by office. Collier County uses the Improved Value on the property appraiser’s website, and its staff can add 20 percent to it. Charlotte County uses a value that is not listed on the property appraiser’s website and has to be requested. The City of Naples and the City of Cape Coral put limits on how old an appraisal can be.
The cost
FEMA’s desk reference lists what a local official must include and what may be left out. The lists below are the parts that matter most to a kitchen or bathroom remodel.
Countertops are not named in FEMA’s list, but the cost forms used by Lee County and the City of Bonita Springs include them.
FEMA also says that if any part of the work requires a permit, all of the proposed work is counted, including the parts that would not need a permit on their own.
Earlier projects
Under the federal minimum, the test applies to each separate application. For years some Florida communities went further and added up improvements over a set period, such as five years.
Florida law changed that in 2025. Section 163.31795 of the Florida Statutes says a local government in the National Flood Insurance Program may not adopt or enforce a cumulative substantial improvement period. The City of Cape Coral told contractors in July 2025 that it would no longer consider aggregate improvements and would make determinations permit by permit.
When we checked, the published codes of the City of Fort Myers and the City of Bonita Springs still described a 12-month period and a five-year period. If your home is in either city, ask the city how it applies the rule today.
A single project still cannot be split to stay under the threshold. Bonita Springs has applicants acknowledge that separating the cost of the work into multiple permits to avoid the review is not permitted, and Charlotte County and Collier County count open permits toward the total.
Your remodel
Four things to find out before you plan a larger project on a home in a flood hazard area.
Look up the address on FEMA’s flood map or your local government’s tool. If the home is not in a Special Flood Hazard Area, the rule does not apply.
An elevation certificate shows where the lowest floor sits relative to the required elevation. A compliant building is generally not subject to the 50% test.
Ask your floodplain office which value it uses. Charlotte County gives this example: with a building value of $250,000, the threshold is reached when the work costs $125,000 or more.
Add up everything in the permit, not just the kitchen or the bathroom. If the total comes close to half the building’s value, talk to the floodplain office before the design goes further.
By community
The determination is made by the local floodplain administrator, working with the building official. It is not made by a contractor, the homeowner, or an insurance adjuster.
City of Fort Myers Community Development inside city limits. Lee County Floodplain Management for Fort Myers addresses outside them.
Both start from the property appraiser’s assessed value of the structure.
City of Cape Coral Development Services, Floodplain Management.
Determinations are made permit by permit.
City of Naples Building Department inside city limits. Collier County Floodplain Management for the wider Naples area.
City of Bonita Springs Community Development.
Building values come from the Lee County Property Appraiser by default.
Village of Estero Building Department inside village limits. Lee County Floodplain Management outside them.
Lee County Community Development, Floodplain Management.
Lehigh Acres is unincorporated.
City of Punta Gorda inside city limits. Charlotte County Community Development outside them.
Charlotte County Community Development.
Port Charlotte is unincorporated.
Good to know
It can. FEMA counts remodeling even when the outside of the building does not change. The rule applies when the home is in a Special Flood Hazard Area and does not meet current flood requirements, and the cost of all the work in the permit is compared with the market value of the building.
No. Lee County states that if a building is already flood compliant, the 50% rule generally does not apply. Charlotte County requires an elevation certificate to show that a building is compliant.
No. It is based on the market value of the building alone. The land, landscaping, driveways, and detached structures are left out. Local governments generally use the county property appraiser’s value for the building, or an appraisal by a Florida-licensed appraiser.
Florida law has barred local governments from adopting or enforcing a cumulative substantial improvement period since 2025, and Cape Coral makes determinations permit by permit. One project cannot be split across several permits to avoid the review, and some counties count permits that are still open.
The floodplain administrator for your city or county, working with the building official. FEMA’s guidance says local officials are responsible for the determination and that an insurance adjuster’s estimate must not be used to make it.
The building must be brought into compliance with current flood requirements. For a house, the federal minimum is a lowest floor at or above the base flood elevation, and several local governments here require one foot above it.
Sources
This guide is general information for homeowners, checked against these sources on October 3, 2026. It is not legal advice, and rules change. Your city or county building department decides what applies to your property.
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