Preservation Magazine, Spring 2017

What It Takes To Repair A 9-Million-Pound American Symbol

The dome of the U.S. Capitol Building completed a 3-year renovation in 2017.

photo by: Architect of the Capitol

This close-up look at the Capitol dome shows the intricacy of its architecture.

At 289 feet tall, the dome of the United States Capitol towers over the eastern end of the National Mall in Washington, D.C., an instantly recognizable symbol of democracy. The cast iron dome itself was completed in 1863, after the nation’s rapid growth necessitated a remodel and expansion of the entire Capitol in the 1850s.

By the 1950s, however, the 9 million–pound dome had numerous fissures, and an attempt to weld them during a 1959–60 restoration was largely unsuccessful. The entire surface was cracking by 2014, prompting a three-year project that was completed in time for the 2017 Inauguration.

We chatted with Joe Abriatis, an engineer and construction manager at the Architect of the Capitol, the government office that stewards the Capitol and surrounding buildings and grounds.


Name: Joe Abriatis, construction manager

Has worked at the Architect of the Capitol since: January 2008

Preservation connection: “I grew up in the construction industry, and my dad used to renovate a lot of old houses, so restoration has always been important to me.”

Primary Problem

More than 1,300 cracks and a corroded gutter system, as well as missing or corroded decorative elements at the top of the dome. “We were getting a lot of rust buildup that was causing things to break and fail.”

Crack Team

In the 1990s, the Architect of the Capitol spearheaded a pilot project to address the cracks. In response, a California firm called Lock-N-Stitch developed a method for inserting pins to fill cracks and adding perpendicular “locks” to stabilize the areas filled in by the pins. The pins are then ground down so they’re flush with the surrounding cast iron. “By repairing [the cracks] in situ, we don’t have to remove these massive cast iron plates that can be 10 feet wide and 6 or 7 feet tall.”

Time Check

“It takes about an hour of labor for every inch and a quarter of repair. So a 6- or 7-inch crack will probably take one worker a day to repair. But compared to dismantling an entire plate and making a new one, it’s a fraction of the cost."

Katherine Flynn is a former assistant editor at Preservation magazine. She enjoys coffee, record stores, and uncovering the stories behind historic places.


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