Sealed structural plans for room additions, lanai enclosures, second-floor additions and bearing-wall openings, with the scope checked against the 50 percent flood rule. Send photos, the survey and your layout.
Homeowners, builders and designers with an existing Florida house: a room addition, a lanai or porch enclosure, a second story, a wall removed or opened up, a larger door or window opening, or a new roof over an addition.
What is in the set
The 50 percent rule, in plain words
In a flood zone, the Florida Building Code treats an addition, alteration or repair whose cost equals or exceeds 50 percent of the building's market value as a substantial improvement. The cost of all the work counts. When it crosses the line, the whole existing building has to meet the flood standards for new construction (FBC, Existing Building 502.2 for additions and 503.2 for alterations). Market value means the building, not the land, and many departments use the property appraiser's value adjusted to market, or a licensed appraisal.
How we handle it: we ask for the flood zone and the building's value on day one, size the scope with the line in mind, and tell you where a revised layout would keep a project under it.
Existing conditions
We work from your photos, measurements and the survey. We do not visit the site. Your contractor verifies field dimensions and concealed conditions, such as the framing inside walls and the footings, and the plans say so.
What we need from you
Photos of the house and the area for the addition, a sketch or floor plan with dimensions, the survey with the flood zone, and any earlier plans you have.
Where we work
Additions and remodels come in from all four areas below. Pick yours:
Questions
What is the 50 percent rule for home additions in Florida?
In a flood zone, if an addition, remodel or repair costs 50 percent or more of the building's market value, it is a substantial improvement, and the whole building must meet current flood standards for new construction. Your building department makes the call, and the cost of all work counts toward it.
Do I need an engineer to remove a load-bearing wall?
In practice, yes: a bearing wall needs a beam or header sized for the load and a path for that load down to the foundation. We draw the beam, the posts and the footings, and your contractor verifies what is inside the wall before cutting. The plans go to the building department with the permit.
Does a small addition have to meet flood elevation?
Not always. Below the 50 percent line, an addition cannot make the building less compliant, and its lowest floor has to be at or above the lower of the existing lowest floor or the required elevation. New foundations must meet the new-construction flood standards. We check your flood zone first.
How do you work from photos instead of a site visit?
We draw from your photos, measurements, the survey and any earlier plans, and the sheets say that your contractor verifies field dimensions and concealed conditions before building. Send what you have, and we say what else we need.
What do you need to quote an addition?
The address, photos, a sketch or floor plan with dimensions, the survey with the flood zone, and the approximate size of the project. We quote a fixed fee and ask for the building's value if you are in a flood zone.
Every project is quoted individually as a fixed fee. Fees depend on scope, complexity, size, jurisdiction and turnaround.
(239) 253-0401 · Pamela@fcs-eng.com
© 2026 Floridian Construction Services, LLC d/b/a FCS Engineering · Florida PE No. 96645 · Engineering Business Registration No. 39643 · All rights reserved.
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