Here's the fun part of "market value" -- the city of Sarasota, the county of Sarasota, the city of Venice, the town of Longboat Key, the city of North Port, the county of Manatee, the city of Bradenton, etc all have variations on how the 50% is calculated.
If you plan to renovate an older home that may fall under the 50% Rule, talk to the appropriate building department to see what is applicable to your home. Be wary of investor fix and flip remodeling that may not have had appropriate permits pulled to avoid the 50% threshold rule as project costs calculated into the 50% could include things such as built-in appliances, flooring, interior finishes, and other finishing materials in addition to structural related materials and costs.
Anyone looking to purchase or sell any pre-FIRM built home should verify the current flood zone designation of the structure (not just the lot). If the home is in a designated flood zone then you should take into consideration any major remodeling that has been done, especially if the quoted living space does not match that provided by the property appraiser's office.
Diane Christner, Realtor, GRI, SFR, CNE