Quick answer: Divide your project cost by the market value of the structure (not the land). If the result is 50% or more and the home is in a FEMA flood zone below the required elevation, the project is generally a substantial improvement or substantial damage, and the whole home must be brought up to current flood rules. Use the calculator below to screen your project.
Last updated: November 2026 · Miniopolis LLC, Florida State Certified General Contractor (CGC1531810), Fort Myers
Screening tool only. Your building department makes the official determination using its own valuation and cost rules.
How the 50% Rule Is Calculated
- Structure value: the building only, not the land. Lee County uses the Property Appraiser’s value unless you provide an appraisal.
- Project cost: labor and materials at market value, including donated labor.
- Usually excluded: plans, permits and surveys, plus items like pools, screens, sheds and fences.
What Happens If You Cross 50%
The home must meet current flood rules, which in unincorporated Lee County means building at least one foot above the Base Flood Elevation. That usually means elevating the home or rebuilding. Cities like Fort Myers, Cape Coral and Fort Myers Beach run their own programs, so check your address. Read the 50% rule explained.
How We Help
- Detailed cost breakdowns for your permit application.
- Scoping a renovation to stay within the limit, or pricing elevation and rebuild options side by side.
- Permits and construction. See permitting and consulting, renovations and storm rebuilds.
Get a 50% Rule Cost Breakdown
Tell us about your project and we will get back to you within one business day, or call (239) 329-8804.
50% Rule FAQ
What is the 50% rule?
For homes in a FEMA flood zone below the required elevation, if repairs or improvements cost 50% or more of the structure’s market value, the whole home must be brought up to current flood rules.
Does land value count?
No. Only the value of the structure counts.
Who decides if my project crosses 50%?
Your local building department, using its valuation and cost rules. This calculator is a screening tool only.