Structural Underpinning for Historic Armory Conversion
Problem
Meavers Construction was tasked with converting a Civil War-era armory on Sullivan’s Island, SC into private residences—a project that required careful structural underpinning of the existing historic structure. However, the bottom of the original footings sat 8 feet below grade, deep within the local water table. Traditional excavation methods were not feasible, posing a major obstacle to safe and effective foundation support.
Solution
With traditional methods off the table, CNT Geotechnical stepped in with a custom-engineered solution. Our team developed a flitch plate support system, installed both inside and outside the historic brick structure. This system was anchored using steel outriggers resting on helical piles designed for an ultimate capacity of 60 kips.
The project’s coastal location on a barrier island meant the soils were highly salt-contaminated. To ensure long-term durability, CNT utilized stainless steel components—resistant to corrosion and ideal for harsh environments.
This innovative system not only stabilized the historic foundation but also provided the support needed for new structural footings, making the renovation possible without compromising the integrity of the original building.
