It is the threshold after which an existing building must be brought up to current flood code standards when any additions or improvements are made, which is especially important to understand in hurricane-prone coastal areas, is “significant improvement.” A significant improvement is defined by the Existing Building Edition of the Florida Building Code as any “repair, alteration, addition, or improvemnt of a building or structure, the cost of which exceeds 50 percent of the market value of the structure.” 

    Note that it is not 50 percent of the value of the entire property, but simply of the structure on the property. Also, the value of the improvement is not reduced if the owner provides the labor.

    The rule does not apply to buildings in the “X” or “D” flood zones, which have an extremely low likelihood of flooding.

    Also, see our blog post What is the purpose of the Existing Building Edition of the Florida Building Code?

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Here’s links to a collection of our blog posts about BUILDING CODES:

• When did the first Florida Building Code (FBC) begin and become effective?

• The home inspector says I have construction defects. How did my home pass inspection by the building department? 

• What is the difference between prescriptive and performance building codes?

• Can a local building department choose to not enforce selected parts of the Florida Building Code? 

• Is the latest edition of the National Electrical Code (NEC) the standard used for the electrical system of new homes?

• Why is the National Electrical Code (NEC) so hard to understand and complicated? 

• What is the purpose of the Existing Building Edition of the Florida Building Code?

• What is the most important sentence to know in the entire National Electrical Code (NEC)? 

• How often does the National Electrical Code (NEC) change? 

   Visit our BUILDING CODES page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.