Exterior Restoration of the State Capitol Completed
After five years of investigation, trial repairs, and construction activity, the $60 million exterior restoration of the state capitol is complete. On March 25, 2020, JE Dunn Construction and their trade partners completed the installation of the copper roof on the capitol and the interior finishes in the tunnel. These activities represented the last of the remaining work items on the exterior project.
The exterior restoration project began in Spring 2015 with the erection of scaffolding around three key areas of the building. Over the next several months, experts investigated the condition of the limestone, granite, mortar, windows, and cast iron. Destructive testing was also done to better understand the conditions behind the stone and learn how the stone was attached to the building’s structure. Throughout the investigation process, members of the exterior design-build team (JE Dunn, ADG, ZFI Engineering, and TreanorHL) spent countless hours devising a strategy to properly address the conditions on the building.
Once the investigation was complete, the trial repair phase began. The design-build team tested various methods to address the conditions on the building and determine which ones would be most effective. By methodically applying the solutions and analyzing the results, the team was able to eliminate options that were not effective or too costly. During this phase, numerous cleaning solutions were applied to the limestone and granite. Laser cleaning was even considered at one point. Various mortar mixes for the stone joints were applied to test for color match and proper adherence to the stone. After dismantling one of the windows on the building, the team learned the initial plan to remove each one as a holistic unit was not possible due to the way they were originally installed as part of the building’s structure. Plans were changed and the majority of the window apparatus was restored in place with some of the pieces being transported to Kansas City for repair. Later in the project when the copper roof replacement was added, trial repairs and mock-ups were instrumental in ensuring a quality installation.
Restoration activities on the exterior started in earnest in July 2016. An intricate scaffolding system was placed around the capitol, starting on the north wing. The scaffolding was climate controlled to ensure the materials would perform according to specifications. Over the next three years, as each elevation of the building was completed, the scaffolding was removed and reinstalled on a new elevation until the exterior was complete. During this time, some of the finest tradespeople in the country – from stonemasons to window restoration experts to lighting restoration specialists – applied their craft at the state capitol.
The result was dramatic, both from aesthetic and functional point of view. 477 of the capitol’s original windows were restored and made watertight. Over 21 miles of mortar joints were re-pointed. Hundreds of thousands of square feet of limestone and granite was subjected to a 3-step cleaning process. Ten of the original ornamental light fixtures were repaired and polished and two new fixtures were commissioned. Over 4,600 repairs were made to damaged limestone and granite blocks on the building. New guttering was installed to ensure proper extrication of water away from the building. The historic steel pocket doors at the front of the capitol were repaired and repainted, including the iconic state seal residing just above them. All twelve exterior elevations of the building were completed in April 2019.
In addition to the restoration work on the capitol, the plazas on the east, north, and west sides of the building received a new concrete topping and an enhanced drainage design. A new ramp for disabled persons was added to the southwest side of the building. The structures for the six battlements around the building and the staircases on the east, north, and west sides were judged by engineers to be structurally unsound. Consequently, stonemasons removed the granite and the structures were rebuilt using modern construction methods. Each granite stone was meticulously returned to its original location. New concrete retaining walls were also added around the capitol.
Repairing the underground tunnel between the capitol and the east parking lot was no easy task. For several years, water had infiltrated the tunnel, sometimes in a slow trickle and other times in a gushing flood. Beginning in summer 2018, the structure was unearthed in sections and new waterproofing was added. Complications arose when oil seepage and old well heads, remnants of the Oklahoma City Oilfield, were discovered. An environmental disposal plan was enacted to dispose of the affected soil. Once the construction work reached northbound Lincoln Boulevard, the street had to be diverted into the House parking lot, so that section of the tunnel could be completed. With the completion of the tunnel waterproofing work, new interior finishes were installed.
The final project in the exterior scope of work was the replacement of the copper roof. Investigations in 2018 revealed the roof to be in worse shape than originally anticipated. In order to properly seal the building’s envelope from water infiltration and ensure a long-lasting solution to the problem, the decision was made to completely replace it. A copper roof was chosen because it is the original material that was used and, with proper maintenance, it will provide a multi-decade solution.
The JE Dunn Construction design-build team is now engaged in demobilization activities. The tower crane is scheduled to be dismantled during the week of April 13th. Once the crane is removed, work around the landscape on the north side of the building will commence. The last retaining walls will be built and storm sewer piping will be added. JE Dunn’s trailer compound will be removed and new sod will be installed. Weather permitting, the demobilization work will be complete by May 20th.