Along the coasts of Florida, Alabama, Georgia, and the Carolinas, tabby was introduced by the Spanish in the seventeenth century as a low-cost and accessible building material. It was manufactured following methods long practiced throughout southern Spain by mixing various compounds including earth, limestone, and clay with lime and then pounding or pouring the resultant mix between boards positioned to define the required building shape. Once the cast was set, the form work was dismantled, repositioned, and refilled with the mix at successively higher building levels.
Tabby in North America is distinguished by the use of oyster shell aggregates and lime derived by burning shells. As with the earlier manufacture along the Mediterranean, the lime and the aggregate were mixed with sand and water and tamped into reusable wooden forms, usually made of horizontal tongue-and-groove timbers. The French Duc de La Rochefoucauld-Liancourt provides a late eighteenth-century observation of the casting process he saw in Beaufort County: “Mortar is poured into frames the length and thickness of the wall to be constructed. These forms have no bottoms but their sides are joined at certain intervals at top and bottom by pieces of wood. The mortar is pounded in with force and when brim full left for two or three days.”
Although no tabby structure securely dated before 1730 survives above ground in South Carolina or Georgia, it is clear that tabby played an important role in shelter and defenses for early Europeans. Other durable building materials, such as brick and stone, were not easily available, especially in the Sea Islands, which lacked outcrops of clay and rock.
Recent research indicates that tabby manufacture was understood around Charleston before 1726, but it did not appear in Beaufort County until construction began in 1731 at Fort Frederick on the Beaufort River. Eventually it became ubiquitous to Beaufort County, where it was used in fortifications, houses, stores, and a variety of outbuildings. It is now represented by a handful of structures in the city of Beaufort (including the Barnwell-Gough House, Tabby Manse, and the Saltus House) and on Spring, St. Helena, Callawassie, and Hilton Head Islands.
Gritzner, Janet Bigbee Hazen. “Tabby in the Coastal Southeast: The Cultural History of an American Building Material.” Ph.D. diss., Louisiana State University, 1978.