The rules below are for unincorporated Pinellas County. Every city has its own fence and shed rules (Clearwater, for instance, requires a permit for installation and replacement of all fence types), so confirm your jurisdiction first.
Fences. In unincorporated Pinellas, permits are generally not required for standard chain link, wood, or vinyl fences, though a zoning clearance may be required in certain conditions. Height limits from the county's published summaries: up to 6 feet along side and rear property lines, and a maximum of 3 feet in front setback areas. Taller decorative options in front setbacks (commonly cited as 4-foot opaque and 5-foot semi-opaque tiers) appear in the Land Development Code but were not verified against primary code text for this article, so check with Development Review Services (727-464-3888) before building tall front-yard fencing. Corner lots must respect sight-visibility triangles at intersections and driveways.
Sheds. Under LDC Sec. 138-3505(c), a shed on residential property needs no permit if it is under 100 square feet and 10 feet or less in height and is not connected to utilities. It must sit at least 3 feet from property lines unless the property is surrounded by a 6-foot opaque fence. Anything over 100 square feet requires a building permit and must meet the full setbacks of the zoning district. Utility connections (electric, water) trigger permits regardless of size. unverified
Other accessory structures. Carports, gazebos, pergolas, and detached garages are treated as accessory structures with district-specific setback and lot-coverage rules; pools and their barriers always require permits. In flood zones, accessory structures have additional limitations.
Practical sequence. 1) Confirm you are actually in unincorporated Pinellas (the Property Appraiser's site shows jurisdiction). 2) Find your zoning district and its setbacks. 3) Call Development Review Services or use the Pinellas County Access Portal to confirm whether your specific project needs a permit or zoning clearance. 4) Locate property pins or get a survey; fences built on a neighbor's land or in easements are a common and expensive mistake. Drainage and utility easements usually allow fences only at your own risk, and the utility can remove them for access.