Masonry | Nebraska State Capitol

In 1995 an inspection of the entire exterior surface of the Nebraska State Capitol was conducted by consultants. They determined that Nebraska’s seasonal temperature extremes and resulting freeze-thaw cycle had caused extensive movement and cracking in the stone building face and roof system sufficient to require major re-construction of these critical building components. The Nebraska Capitol Exterior Restoration Project to restore the exterior façade began in the fall of 1997. Although the entire exterior masonry face of the building had been cleaned and tuck-pointed at least twice in the past, the level of restoration required in 1997 was the most extensive since original building construction during the 1920’s.

Working with the Office of the Capitol Commission on the Capitol Exterior Restoration Project are project team consultants Wiss, Janney, Elstner, Inc. of Chicago and Bahr, Vermeer & Haecker Architects of Lincoln. The general contractor for the project is Mark I Waterproofing and Restoration Company of Dolton, Illinois.

Because of the National Historic Landmark, the restoration contractor is worked preserve the integrity of the building, reusing rather than replacing materials whenever possible. This conservation approach insured Bertram Goodhue’s carefully matched limestone façade remained intact. As each stone is removed from the building it was numbered and cataloged, then returned to its exact location when repairs were completed and reassembly occured. Through a coordinated effort between the Nebraska Capitol Archives and the archives at the Indiana Limestone Company the state was able to replace damaged limestone with new material quarried from the same Indiana limestone pit from which the original stone was supplied over 80 years ago.

The project was divided into five phases.

 First phase– North Entrance Masonry

Second Phase– Tower and Turret Masonry

Third Phase– Dome and Drum Masonry and Tile

Fourth Phase– Roof of Building Base

Fifth Phase-Lower Building Masonry (Floors 1-3)

In each phase, the exterior masonry was cleaned of organic growth (algae and moss). This cleaning process involved the application of a biocide which killed the micro-organisms which blacken the building face. Then a process of “facade gommage” using air-driven glass powder cleaned the dead organisms from the surface of the stone. It is anticipated that water cleaning of the building will be done as new growth requires.

Where excessive water penetration and freeze-thaw damage required, the masonry walls were disassembled, damaged backup brick replaced and internal wall flashing installed. During the reassembly process a small interior cavity was created to allow water penetrating the walls in the future to migrate out of the walls through weep holes.

The entire exterior facade of the Nebraska State Capitol was tuck pointed and cracked stones repaired or replaced. Some of the damaged stone pieces required the installation of patches and epoxy filler to bond and seal the cracks. Replacement stone taken from quarries originally active in the 1920’s replace the irreparably damaged stone removed from the facade. Using a formula found in the Capitol archives, contractors replicated the original mortar mix using sand from Platte River sand pits where the original sand was quarried.

Restoration began in January 1999 with the north entrance grand staircase and porte cochere. The bison wing walls and granite steps at this entrance were disassembled, realigned, waterproofed and the granite steps reset. Simultaneously, Phase 2 restoration of the tower began in the summer of 2000 scaffold was erected around the full height of the 400 foot tower.

Restoration of the tower limestone veneer involved the removal of organic growth, dismantling and rebuilding of the corner turrets at the 300 foot level and parapet walls at the tower observation level, installing expansion joints at each floor to allow for movement in the tower façade and repairing areas of excessive water penetration. Maintenance of the bronze tower windows and stone tuck-pointing was also accomplished at this time. The gold glazed ceramic tile dome was cleaned and required a minimal amount of joint maintenance at that time. While the tower was accessible the Office of the Capitol Commission took advantage of a Save Outdoor Sculpture! grant and brought in conservators to structurally evaluate, clean and patinate the 19’tall statue of the Sower and its 12′ tall pedestal which crowns the Capitol.

Once the tower work was completed the project moved to the south entrance and loading dock area. This entrance, south promenade stair and loading dock walls were disassembled and rebuilt during the 2003 and 2004 construction seasons. In 2005 work began on the parapet walls and roof area of the main north entrance pavilion using techniques fine-tuned in previous locations on the building. In the spring of 2006 restoration work began on exterior of the West Legislative Chamber, the west ground floor entrance and west promenade stair. Work on the East Legislative Chamber, east promenade stair and east ground floor entrance was completed in 2010. Work on these entrances followed the pattern of other work during the project, disassembly of the structure, replacement of the red clay brick with concrete brick, and reassembly with flashing to minimize water infiltration. Replacement of the existing copper roof of the Capitol’s 437 foot square base began in 2007 and was completed in 2010. The installation of the new copper roof included the installation of insulation under the roof to slow heat loss through the roof of the Capitol. The restoration of the grounds was competed in the fall of 2011. 

Information about the project may be obtained from the Office of the Capitol Commission by contacting the Office of the Capitol Commission, P.O. Box 94696, Lincoln, Nebraska 68509-4696.  Matt Hansen, (402)471-6655.