North Capitol Building Case Study

The Utah State Capitol North Building, currently under construction, features 80,000 SF of classically designed cubic granite detailing, including fifty-two Ionic capitals at the top of 48’ registered prefabricated pilasters with full entasis. The project’s detailed facade and stringent seismic specifications presented several challenges which were overcome through the innovative engineering methods utilized during the collaborative design-build phase. The original project facade was designed so that the stones were individually hand-set, but the concept of pre-fabricating stone onto panels off-site and then installing the panels onto the building was explored during the design-build process. Because the project’s originally designed structure would not support the weight of the heavy cubic stone panels, KEPCO+ worked with the design team to engineer a fully integrated gravity-stacked panelized facade system. Movement connections were used between the panels and the building to meet seismic specifications. The revised system allows 70% of the stonework to be panelized, reducing the overall installation schedule and increasing the quality of the facade. More than 400 panels, ranging in weight from 3000 pounds to 12,000 pounds with individual stones spanning up to 12” thick were engineered.

Mock-ups and 3D modeling technologies were utilized to ensure the heavy cubic detailing met the aesthetic specifications prior to stone fabrication. Each column capital design was created in foam with the use of a C&C machine. Once the design was approved by the architects, the foam models were sent to the stone fabricator in Italy to replicate. Additionally, the column and pilaster entasis presented challenges when panelizing and were mocked-up for review. To accommodate the entasis tapering, the original designs incorporated 6” thick cubic stone with joint returns, but the mock-ups did not meet the architect’s aesthetic desires. Additional mock-ups were created with 2” epoxied mitered corners which hid the joints and achieved the desired aesthetics. Facade installation began in February of 2024 and is scheduled to be completed in the fall of 2025.