Is an Engineer Stamp Required for My ADU Project in Florida?

Florida cities — Miami, Tampa, Orlando, Jacksonville — review structural drawings for accessory dwellings under the Florida Building Code, and the PE seal is the standard requirement. The seal must show the engineer's name, Florida PE number, and date, and the engineer must be in responsible charge of the engineering. Detached ADUs, garage conversions, and additions are treated the same at the structural level. Owner-builders don't escape the requirement: the building department asks for the seal regardless of who drafted the plans.

The engineer reviews the floor plan and elevations, designs the foundation for sandy soils and the high water table — monolithic slabs and stem walls are common — sizes beams, headers, and the lateral system, and checks hurricane wind design per the Florida Building Code wind maps. In the high-velocity hurricane zone, product approvals and opening protection get extra scrutiny. Garage conversions are checked for floodplain compliance where triggered. Bring the site survey, the geotechnical report, and the architectural plans. Wind design is the item most ADU plans miss.

Use this checklist before engaging an engineer for your ADU: • Engineer of record holds an active Florida PE license, verifiable on the state roster • Dimensioned floor plan and elevations ready for structural review • Site survey showing setbacks, easements, flood zone, and existing structures • Wind design per the Florida Building Code wind maps • Product approvals and opening protection verified in the HVHZ • Garage conversions: existing slab evaluated for dwelling loads • Engineer confirms they'll respond to plan-check corrections on sealed sheets • Seal shows name, Florida PE number, and date on every sealed sheet