2-year renovation starts for Capitol's famous dome

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2-year renovation starts for Capitol's famous dome
Detail of the ceiling of the US Capitol Rotunda is seen during a tour of the dome December 19, 2013 in Washington, DC. The United States Capitol Dome, symbol of American democracy and world-renowned architectural icon, was constructed of cast iron more than 150 years ago. The Dome has not undergone a complete restoration since 1959-1960 and due to age and weather is now plagued by more than 1,000 cracks and deficiencies. The Architect of the Capitol began in November, a multi-year project to repair these deficiencies, restoring the Dome to its original, inspiring splendor.
Eugene Poole Jr., architect and project manager for the Architect of the Capitol (AOC), opens an access port looking into the Rotunda during a tour to the top of the US Capitol dome December 19, 2013 in Washington, DC. The media was given a tour of the Capitol dome before the start of long awaited renovations.
The fresco 'The Apotheosis of Washington' above the rotunda of the US Capitol dome is seen during a tour of the dome December 19, 2013 in Washington, DC. The United States Capitol Dome, symbol of American democracy and world-renowned architectural icon, was constructed of cast iron more than 150 years ago. The Dome has not undergone a complete restoration since 1959-1960 and due to age and weather is now plagued by more than 1,000 cracks and deficiencies. The Architect of the Capitol began in November, a multi-year project to repair these deficiencies, restoring the Dome to its original, inspiring splendor.
A photographer works on the upper catwalk of the U.S. Capitol Dome under the Constantino Brumidi's painting of the 'Apotheosis of Washington' on the ceiling of the U.S. Capitol's rotunda during a media tour December 19, 2013 in Washington, DC. The dome of the U.S. Capitol will be undergoing a restoration project to halt deterioration in the dome's cast iron as well as ensuring the protection of the interior of the dome and rotunda.
A view of the inside of the U.S. Capitol's rotunda during a media tour December 19, 2013 in Washington, DC. The dome of the U.S. Capitol will be undergoing a restoration project to halt deterioration in the dome's cast iron as well as ensuring the protection of the interior of the dome and rotunda.
A view of the US Capitol dome of the US Capitol December 19, 2013 in Washington, DC. The Dome has not undergone a complete restoration since 1959-1960 and due to age and weather is now plagued by more than 1,000 cracks and deficiencies. The Architect of the Capitol began in November, a multi-year project to repair these deficiencies, restoring the Dome to its original, inspiring splendor.
U.S. Capitol Police Officer Adam Taylor holds open one of the coffer windows in the ceiling of the U.S. Capitol dome during a media tour December 19, 2013 in Washington, DC. The dome of the U.S. Capitol will be undergoing a restoration project to halt deterioration in the dome's cast iron as well as ensuring the protection of the interior of the dome and rotunda.
Water damage is visible in the space between the inner and outer domes of the U.S. Capitol during a media tour December 19, 2013 in Washington, DC. The dome of the U.S. Capitol will be undergoing a restoration project to halt deterioration in the dome's cast iron as well as ensuring the protection of the interior of the dome and rotunda.
The infrastructure surrounding the rotunda of the US Capitol dome is seen during a tour of the dome December 19, 2013 in Washington, DC. The United States Capitol Dome, symbol of American democracy and world-renowned architectural icon, was constructed of cast iron more than 150 years ago. The Dome has not undergone a complete restoration since 1959-1960 and due to age and weather is now plagued by more than 1,000 cracks and deficiencies. The Architect of the Capitol began in November, a multi-year project to repair these deficiencies, restoring the Dome to its original, inspiring splendor.
The Capitol Building in Washington, DC, seat of the United States Congress, at the time of the construction of its dome.
The dome of the Capitol building, Washington DC, under construction around the time President Abraham Lincoln took office.
Construction work on the U.S. Capitol building in Washington.
Washington Post Marathon with a backdrop of the Capitol Dome.
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WASHINGTON (AP) - A world-famous symbol of democracy is going under cover, as workers start a two-year, $60 million renovation of the U.S. Capitol dome.

Curved rows of scaffolds, like Saturn's rings, will encircle it next spring, enabling contractors to strip multiple layers of paint and repair more than 1,000 cracks and broken pieces. The dome will remain illuminated at night and partly visible through the scaffolding and paint-capturing cloths. But the Washington icon -- and portions of the Rotunda's painted ceiling that lies below -- will be significantly obscured for many months.

The project is beginning just as the nearby Washington Monument sheds scaffolding that was used to repair damage from a 2011 earthquake.

Half-completed when Abraham Lincoln stood beneath it to summon "the better angels of our nature" in 1861, the Capitol dome has since towered over Washington, which limits building heights to 130 feet. Time, however, has let water seep through hundreds of cracks. The water attacks cast iron, which "continues to rust and rust and rust," said Stephen T. Ayers, Architect of the Capitol.

This first major renovation in more than 50 years should add decades of structural integrity to the dome, which Ayers calls perhaps "the most recognizable symbol across the globe." The $60 million undertaking will heal inner wounds, he said, without changing the way the dome looks from the ground.

Much of the work will be done at night and on weekends. It won't be as flashy as the 1993 helicopter removal and return of the 19-foot Statue of Freedom from the dome's top.

The Capitol's crowning piece is actually two domes, one nested under the other like Russian dolls, and separated by a web of cast iron braces hidden from view. From the ground it looks like a massive structure that would be too heavy for the building to support if it were indeed made of the solid stone it appears to be.

Instead, it is cast iron painted to look like masonry. The lighter material and open space between the inner and outer domes create a physically sustainable structure. But it's by no means puny.
The dome's iron and masonry weigh 14.1 million pounds, said Kevin Hildebrand of the Capitol architect's office. He led reporters up narrow, spiraling stairs that reach the Rotunda's top, and then give access to the in-between world of girders separating the two domes. Ultimately the steps lead outdoors, to a panoramic walkway beneath the 12-columned lantern, or tholos, topped by the Statue of Freedom.

After a 1990 rainstorm left puddles on the Rotunda's stone floor, workers found that bird nests had clogged gutters atop the Capitol, helping water penetrate outer walls and streak interior surfaces.

Then they found bigger problems. Hundreds of cracks and pinholes in the cast iron exterior added to the seepage.

Pans now capture the water. Congress finally agreed to spend $60 million for a better, more lasting solution.

"It is the symbol of our country," Hildebrand said. "It is an icon that has to be preserved."

The 150-year-old cast iron is low-quality by today's standards, he said.

"It's an archaic material," Hildebrand said. A dome today probably would be built with glass and steel, he said. But Capitol workers must deal with relatively brittle iron that doesn't respond well to welding.

First they must remove, capture and safely dispose of several layers of lead-based paint. When they reach bare iron, they must quickly prime and paint it section by section, Hildebrand said, because it will "flash rust" in eight hours.

To mend cracks, workers will drill and tap damaged areas, and then insert steel pins. "Metal stitching" will complete the process.

Before repairing water damage inside the Rotunda, workers will hang a giant doughnut-shaped drop cloth just below the painted ceiling. Rotunda visitors whose necks can stand to crane will still see "The Apotheosis of Washington" through the doughnut hole. The 4,664 square-foot painting, 180 feet above the Rotunda floor, depicts George Washington becoming god-like, aided by figures from classical mythology.

"If these repairs are not made, the artwork in the Rotunda, including the Apotheosis of Washington and the Frieze of American History, are at great risk of damage due to water leaks," says the Architect of the Capitol's Web site. "There is only one Capitol Dome," it says, and the office "is committed to preserving it for generations to come."

The architect's office will update the renovation's progress at www.aoc.gov/dome.
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Follow Charles Babington on Twitter: https://twitter.com/cbabington.
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