Covered Way Wall Preservation Project

 

Structure Description

The covered-way wall is a masonry structure built of locally quarried coquina. The wall retains the inboard side of the glacis and forms a protected area between the moat and the exterior embankment (glacis) along the northern, southern, and western side of the fort. The wall varies between 4 to 5 feet in height. The wall runs for 1,864 linear feet and has more that 10,000 square feet of exposed surface. Prior archaeological investigations indicate that the wall extends an additional 6 feet below grade. This coursed wall has been constructed using individual, roughly-squared building units (stone) that vary in size. When building, where voids needed to be filled, smaller coquina stones and shell were used as pinnings to solidify its vertical surface and provide stability to the structure. The mortar used was a lime mortar kilned from shell to make a lime putty. The lime putty was mixed with sand to make the mortar.

 

 

Structure Condition

Overall, the condition of the covered way wall is fair. As of 1986, the Historic Structure Report (HSR) recommended approximately 20 percent, or 2,000 square feet, of the covered way wall be re-pointed and 100 cubic feet of missing stone be replaced. Since the 1986 HSR, the amount of vertical stone replacement, severely eroded/deteriorated cap stones, and square footage that needs re-pointing has increased dramatically. Some sections have had recent repairs and are in a stabilized state. One such section was out of plumb and had become unstable. This section was disassembled and reassembled in 2005 and is located at the entrance/exit point of the covered way wall by the Cubo Line. Untreated areas that have considerable deterioration of stone, some lateral loading from hydrostatic pressure, and previous inappropriate repairs have left these walls in a fragile condition. A high percentage of excessively hard Portland cement-based mortar is in place within the mortar joints and it is accelerating the stone's deterioration. Some settlement cracks have been observed. The deteriorated mortar joints are a venue for moisture infiltration and contribute to an accelerated rate of disintegration of the mortar and stone.

 

 

Scope Of Project

Castillo De San Marcos National Monument Masonry staff worked within the Secretary of the Interior’s Standards for the Treatment of Historic Properties as a preservation crew to complete the repairs. Completed work has corrected prior inappropriate repairs, deteriorated stones, and mortar. The wall repair aids in stabilizing the structure while retaining historic details. The project was completed in 2015.