The Capitol dome, the nation’s grandest symbol of federal authority, has been dinged by years of inclement weather, and its exterior is in need of repair.
The dome has 1,300 known cracks and breaks. Water that has seeped in over the years has caused rusting on the ornamentation and staining on the interior of the Rotunda, just feet below the fresco “The Apotheosis of Washington,” which is painted on the Rotunda’s canopy.
“The dome needs comprehensive rehabilitation,” said Stephen T. Ayers, the architect of the Capitol, whose office oversees the building’s physical state. “It’s a public safety issue.”
The skirt of the dome — the section around the base of the original sandstone foundation — was fixed up recently at a cost of about $20 million, but an additional $61 million is needed to repair and restore the rest of the structure’s exterior.
The Capitol’s first dome, made of copper-covered wood, was completed in 1824 but by the 1850s was deemed too small. It was also seen as a fire hazard in a place where oil lamps, British attacks and other events had caused blazes. A cast-iron replacement was envisioned, and lawmakers, thrilled with the idea, appropriated $100,000 to begin construction, with the acquiescence of President Franklin Pierce.
Construction on the cast-iron dome began in 1856 and progressed through various architects, disputes over the design and the Civil War, when the project was continued in part by workers who were afraid that the military would take the metals and repurpose them for war use, said Donald A. Ritchie, the Senate historian.
The Statue of Freedom, which sits triumphantly atop the nine million pounds of ironwork that makes up the dome, was completed in December 1863, topping the project. The interior was finished in 1866, its famous fresco revealed. Total cost: $1,047,291, or more than $15 million in today’s dollars.
The dome was completely restored in 1960 during the construction of the Capitol’s East Front extension. Weather remains its biggest enemy: precipitation pelts the exterior, and the statue endures the occasional strike of lightning. At least 100 pieces of the dome have fallen off or been removed, including a 40-pound cast-iron decorative acorn.
Viewed from a (sort of scary) balcony between the fresco above and a frieze depicting American history that lines the Rotunda’s interior, tourists with iPhones and fanny packs can be seen lingering in awe hundreds of feet below, unaware of the water damage and chipping paint above.
“When you have those conditions on the outside,” said Mr. Ayers, the Capitol’s architect, “it really accelerates deterioration on the inside,” including possible damage to the fresco, which is painted on plaster.
In other words, just as it is best to fix a bathroom leak before it causes damage to the rest of the house, the dome repairs could prove much more expensive over time.
The project will involve taking apart many pieces of the dome, one at a time, and then putting them back together once repaired, much like a puzzle, Mr. Ayers said.
In many ways, the process reflects the history of the Capitol and the nation, said Mr. Ritchie, the historian. “The Capitol building is an interesting conglomeration,” he said. “It is a whole series of buildings put together at different times, and in that way it is a nice reflection of American democracy, which was put together piecemeal from a lot of different materials. It reflects one motto of our nation, ‘E pluribus unum,’ Latin for ‘Out of many, one.’ ”
“The Capitol is a wonderful story of the history of our nation,” Mr. Ritchie said. “And as a result it is preserved very carefully to maintain the story, not to mention to keep it from leaking into the Rotunda.”