That will be in your local flood ordinances,
The Florida Building Code, Building and Residential, require local jurisdictions to adopt flood ordinances which contain recommended guidelines, and which meet FEMA regulations, and the FEMA regulations address "structure" and "building"; however, those terms are not necessarily the same as "buildings" and "structures" as the building codes think of them.
(underlining is mine)
From
https://www.fema.gov/national-flood-ins ... initions#B -
Building.
- -
A structure with 2 or more outside rigid walls and a fully secured roof, that is affixed to a permanent site;
- - - or A manufactured home (a "manufactured home," also known as a mobile home, is a structure built on a permanent chassis, transported to its site in 1 or more sections, and affixed to a permanent foundation);
- - - or A travel trailer without wheels, built on a chassis and affixed to a permanent foundation, that is regulated under the community's floodplain management and building ordinances or laws.
- - "Building" does not mean a gas or liquid storage tank or a recreational vehicle, a park trailer, or other similar vehicle, except as described above.
The definition for a "building" says it is a "structure ... ", which means we need to find out what FEMA considers is a "structure".
From
https://www.fema.gov/structure - Definition/Description
- - For floodplain management purposes,
a structure is a walled and roofed building, including a gas or liquid storage tank, that is principally above ground, as well as a manufactured home. The terms "structure" and "building" are interchangeable in the National Flood Insurance Program (NFIP). Residential and non-residential structures are treated differently. A residential building built in a floodplain must be elevated above the Base Flood Elevation (BFE). Non-residential buildings may be elevated or floodproofed.
That leaves the question of: does the gazebo in question meet the definition of a "building" or a "structure" under FEMA (some would, some would not, depends on how they were designed and built) and what the local flood ordinance requires for "buildings" and "structures",
I should add this too: if that gazebo is not exempted from requiring a permit (it may be small enough to be exempted out of permitting, but probably is not exempted out), then it would be required meet all permitting and code requirements, which include flood. Keep in mind that items exempted from a "permit" still are required to "meet code" ... just no permit is required.