Oklahoma State Capitol Exterior Rehabilitation

Client

Oklahoma Construction & Properties Department

Services

Architectural Design, Planning

Specialty

Historic Preservation

Location

Oklahoma City, OK

Project type

Renovation

Partner

ADG Blatt, JE Dunn

Restoring the seat of government

Home to all three branches of government, the young State of Oklahoma constructed its State Capitol between 1914 and 1917. By 2014, after a century of continuous use in the harsh Oklahoma weather, the building’s exterior masonry was deteriorating. Beyond limiting its ability to meet the State’s needs for the next 100 years, the deterioration presented a safety hazard.

The Oklahoma State Capitol was constructed of three types of stone. Bedford limestone, more commonly known as Indiana limestone, a pink granite known as Tishomingo quarried near Troy, Oklahoma, and a black or gray granite from Cold Spring, Oklahoma. Photo credit: Oklahoma Historical Society

Stopping deterioration for safety

In 2015, the design-build exterior rehabilitation—the first comprehensive rehabilitation of the historic building—was designed to stop deterioration and correct damage to the century-old capitol to protect visitors and occupants and improve the exterior envelope performance.

Before and after

Designing the exterior rehabilitation

As the design architect and historic preservation specialist, we directed field investigations to assess existing conditions and developed design solutions for typical and special exterior masonry, cast iron, and copper repairs. The exterior project included repairing and cleaning granite and limestone; repairing historic steel windows and adding storm windows; installing historically appropriate ballistic windows; restoring decorative cast iron spandrel panels, repairing steel window frames; repairing historic doors; replacing the copper roof; restoring decorative masonry elements; and exterior historic lighting. Our design team developed quality control testing during construction for sealants, ultrasonic determination of concealed metal corrosion on steel window sills, and developing water spray testing protocols based on AAMA standards.