Remodeling and Home Additions on Sullivan's Island, SC

Sullivan's Island regulates the size and shape of a house more closely than anywhere else we work. The Town's zoning ordinance sets a height limit, a foundation-height limit and a cap on total living area tied to lot size, and a Design Review Board reviews new construction and exterior renovations. All of it is published, so a project can be checked against the ordinance before anyone draws it. Figures below were read from the ordinance and the Town's website on 13 October 2026.

Permits on Sullivan's Island: the Town, then the DRB

Building permits come from the Town of Sullivan's Island, whose building and planning staff work from Town Hall at 2056 Middle Street. Exterior changes also go to the Design Review Board, a seven-member board appointed by Town Council that the Town describes as a historic preservation board reviewing new construction and renovations in the residential and commercial districts. It meets on the third Wednesday of each month, and the application deadline falls roughly four weeks before each meeting, so a package that misses the deadline waits a full month. We assemble the drawings and material board to the Board's checklist; our Sullivan's Island DRB approval guide walks through the package.

Height: 38 feet from natural grade

Section 21-24 limits a principal building to 38 feet of overall height, measured from the natural ground at the center of the building to its highest point (chimneys excepted), and never more than 40 feet above the crown of the nearest street. The DRB may weigh a lower height when it judges neighborhood compatibility. Because flood elevation pushes the first floor up, those 38 feet have to hold the raised foundation, every floor and the roof, so ceiling heights, mechanical chases and roof pitch get settled before the architecture does.

Foundation height, and the rules for historic houses

Section 21-31 keeps the lowest horizontal structural member of a principal building within 8 feet of finished grade and the finished floor within 9 feet 4 inches, with a design-flood-elevation alternative where the base flood elevation conflicts; the DRB may grant up to one foot. Designated historic buildings follow Section 21-44 instead, which keeps the finished floor of an elevated historic house no more than 3 feet above finished grade. The Town's 2003 Historic Sites Survey inventoried more than 300 principal buildings, so we check the Town's historic resources map before planning to raise or add to an older cottage.

Additions and the living-area cap

Section 21-27 caps principal building square footage by lot size: on a lot of 5,000 square feet or less, 2,400 square feet in total. The count includes all enclosed living space but not porches, decks, exterior stairs or storage-only space under the house. Before designing an addition we measure what the existing house already uses against that cap. On a historic property, Section 21-43 lets the DRB relax pre-existing nonconforming setbacks so an addition can stay in keeping with the house. Our elevated and second-story additions guide covers the construction side.

Substantial improvement and the renovation ceiling

Under FEMA's substantial-improvement rule, if the cost of the work exceeds 50% of the structure's market value, the whole house has to be brought into current flood-elevation compliance, which can mean lifting it or rebuilding the lowest floor. An addition counts toward the same threshold. Owners either keep a phase below the line or plan the elevation as part of a whole-home project; the expensive outcome is discovering the threshold halfway through. We run that number with you before you sign. Our FEMA 50% rule guide shows how the calculation works.

Materials That Survive the Salt

Stainless 316 hardware, copper or marine-rated bronze for any exposed exterior fixtures, fiber cement or vertical-grain cypress siding, impact-rated windows, and pressure-treated framing on every exterior wall. We've watched 304 stainless rust at the screw heads within 18 months on Sullivan's. Specifying the right grade is the difference between a 20-year exterior and a 5-year exterior. The cost premium is small. The repair-vs-replace difference is enormous.