United States Capitol Dome, Washington, District of Columbia — Historic Dome Restoration

Project/Concept Narrative

A symbol of American democracy, the Capitol Dome is one of the most recognizable architectural landmarks in the world. In the first comprehensive restoration in more than half a century, the Dome underwent a multi-year project to repair cast iron defects, improve water-tightness, restore structural and decorative elements, and protect the Dome from corrosion and deterioration. Using innovative technology and historical tradecrafts, the project team repaired more than 1,300 cracks, repaired or recast intricate ornaments, gutters, and balustrades, removed hazardous materials, upgraded mechanical and electrical systems, and repainted inside and out, using a historical palette. A highly trafficked government building with invaluable art and statuary, the Dome required extensive protection, while maintaining full accessibility. As stewards of an American emblem, the project team treated the Capitol Dome with the respect and attention to detail that befits a national treasure. Dome, Washington, District of Columbia — Historic Dome Restoration

Scaled Site/Location Plan

United States Capitol Dome, site plan United States Capitol Dome, Washington, District of Columbia — Historic Dome Restoration

Elevation View

United States Capitol Dome, elevation view United States Capitol Dome, Washington, District of Columbia — Historic Dome Restoration

Section View

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United States Capitol Dome, section view United States Capitol Dome, Washington, District of Columbia — Historic Dome Restoration

Finished Photo

United States Capitol Dome, after restoration United States Capitol Dome, Washington, District of Columbia — Historic Dome Restoration

Finished Photo

United States Capitol Dome and Capitol Building, in context after restoration United States Capitol Dome, Washington, District of Columbia — Historic Dome Restoration

Finished Photo

Rotunda, after restoration United States Capitol Dome, Washington, District of Columbia — Historic Dome Restoration

Before and After Photos

Column capital, before restoration Column capital, after restoration United States Capitol Dome, Washington, District of Columbia — Historic Dome Restoration

Before and After Photo

Acorn finial and its flower petal base, before and after restoration United States Capitol Dome, Washington, District of Columbia — Historic Dome Restoration

Before Photo

United States Capitol Dome, before restoration United States Capitol Dome, Washington, District of Columbia — Historic Dome Restoration

Sustainable Intent and Metrics

The dome of the United States Capitol Building is a unique and iconic structure. Except for the Rotunda floor level, when built, it was not heated or cooled. The interstitial space between the outer and inner domes remains unconditioned today. Lighting in the Capitol was originally by candle, whale oil lamps, and later by kerosene and natural gas. By 1898 most of the Capitol was lighted by incandescent bulbs. In the 1930s air conditioning was added throughout the Capitol, including the Rotunda.

Sustainable strategies for this restoration included: replacement of air conditioning ducts for greater efficiency; replacement of Rotunda Lighting study - First Visitors’ Gallery (day) lighting, that illuminates the inner Dome and the Apotheosis of George Washington with efficient metal halide and LED lamps; installation of efficient task lighting in the skirt and the interstitial space; and upgrading of all electrical fire alarms and communications serving the tour route to the tholos. (The tholos is the highest part of the dome, on which the Statue of Freedom stands.)

All the systems are tied to a network to monitor and control usage to reduce energy consumption.

Lighting study - First Visitors’ Gallery (night) United States Capitol Dome, Washington, District of Columbia — Historic Dome Restoration

Rotunda Concepts

Historic paint analysis revealed the previous color palettes of the rotunda. Paint samples were taken and then photomicrographic analysis was performed. Paint layers from different time periods were identified, resulting in color palettes for the orginal paint layer from 1866, and additional paint layers from 1906 and 1974. The chose a hybrid color palette for 2016 that was respectful of two different historical points in time, the 1866 color palette which was too dark, and the 1906 color palette, which had little contrast.

Original rotunda paint scheme (1866) Rotunda paint scheme (1906)

Rotunda paint scheme (1974) Hybrid rotunda paint scheme (2016) United States Capitol Dome, Washington, District of Columbia — Historic Dome Restoration