Architect of the Capitol Previews Dome Restoration
While climbing the 349 stairs winding between the Crypt and the top of the Capitol Dome, the water leaks that Architect of the Capitol Stephen Ayers aims to halt are evident.
Pausing about 90 feet above the marble floor of the Rotunda, one can take stock of the light water stains discoloring the walls below the frescoed band, or “frieze,” and the rust-colored grime atop the ledges peeking out over the rails.
Kevin Hildebrand, head of the AOC’s Architecture Division, pointed out the spots on Thursday, suggesting that the heavily cracked cast-iron Dome constructed more than 150 years ago is “like having a bridge as the roof of your building.”
If constructed today, the iconic structure would probably be built with steel and glass, Hildebrand said, not 8.9 million pounds of cast iron.
But the AOC isn’t rebuilding one of America’s most prominent symbols of freedom — they are renovating it.
The first signs of construction in the nearly $60 million Capitol Dome Restoration project will appear in the Rotunda in the next month or two, and rings of scaffolding should start to rise from the roof this spring, Ayers said Thursday.
Views of one of the world’s most recognizable landmarks certainly won’t be great over the course of the next two years, and the massive scaffolding project has risks, Ayers acknowledged, but the restoration work is desperately needed.
About 1,300 cracks crisscross the cast iron shell of the Dome, constructed 150 years ago, and more than 100 pieces have been removed to keep the grounds safe from falling debris since the last total restoration, completed in 1960.
“Those cracks and missing pieces are water leaks into the Dome,” Ayers said during a briefing in the Capitol Visitors Center, explaining that the cast iron “continues to rust and rust and rust.”
More than 40 of those corroded metal chunks, including an 80-pound decorative acorn, were spread across a table to his right. Combined with photos taken by AOC workers who started crawling up to inspect the Dome every two or three years beginning in the mid-1990s, the props provided a scope of the toll that time and nature have taken.
“It’s certainly not going to be great over the course of the next two years, but when we do take the scaffolding back down, the quality of the materials that are used in today’s construction processes are much better than they were 50 years ago,” he said.
The entire project should be wrapped up within two years, he predicted, “certainly before the next presidential inauguration.”
Ayers announced the restoration project in October after AOC awarded a joint $40.8 million contract to two construction companies, Turner and Smoot. Since then, contractors and a team of consultants have been awarding subcontracts and reviewing scaffolding designs, materials and methods of work.
“Like any project that you might do in your home, it’s the planning and preparation that takes as long as the work itself,” Ayers said.
With help from the National Institute of Standards and Technology, the team identified the strongest and most viable technique for workers who would be stationed 200 feet above the ground. Rather than welding, workers will use a mechanical “lock and stitch technique” of drilling out cracks and stitching them together with a series of steel pins.
They are also making plans to strip off about a dozen layers of lead-based paint that must be captured and contained. To do so, paint blasting will be done in phases, inside white enclosures that would move around the Dome over the course of two years.
Planning continues, and construction timelines are still being finalized.
Inside the Rotunda, workers will construct a covered walkway to protect those travelling between the House and Senate chambers. A 96-foot walkway will shield passersby as workers install a doughnut-shaped canopy to protect the project. Some of the artwork will be covered, too.
About 100 feet above the floor, workers will remove 11 of the window panels ringing it to install a system of rigs that will support the protective fabric doughnut. The fabric will stay in place for the duration of the project, while still allowing views of “The Apotheosis of Washington” fresco, depicting President George Washington on his ascent to the heavens.
Outside, workers will install vertical scaffold towers on the West Front. Then, they will construct scaffolding that bridges over the West Front terrace and erect a work platform around the roof of the Capitol. Rings of scaffolding will then begin to extend up from the base of the Dome.
Ayers said the scaffolding is one of the riskiest parts of the process.
“Getting all that scaffolding here, lifting it up to the roof of the Dome and then getting it installed and taken back down is just a massive logistical effort that’s probably one of the biggest risks on the job,” he said.
Luckily, AOC learned some lessons about working on the structure during a 2012 restoration of the Dome skirt, including how to complete a project on time and on budget and also which repair techniques are best suited to the historic structure.
After you take all the paint and primer off the dome, Ayers said, “the cast iron of this generation flash-rusts in eight hours,” so the timely application of new, gleaming white paint is essential. “We have to have those processes down so we don’t have to do repeat work,” he explained.
After explaining the ins and outs of the project, Ayers was asked if he could guarantee that the project would not exceed the $59.55 million budget.
“Guarantee — that’s a big word,” he quipped, “but we’re pretty confident — I’ll give you that.”