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Fire Protection at the U.S. Capitol Complex
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Issue 20: Fire Protection at the U.S. Capitol Complex

By Michael L. Edwards, P.E.

The United States Capitol complex is comprised of the U.S. Capitol, Senate Office buildings, House Office buildings, Library of Congress buildings, Capitol Power Plant, U.S. Botanic Garden and the Supreme Court building. Collectively there is over one million square meters (11 million square feet) woven together by the park-like Capitol Grounds. While the American and international political history of the complex is obvious, it is also extremely rich in architectural history. From the laying of the Capitol cornerstone in 1793, to the opening of the Capitol Visitor Center later this year, and all the construction in between, these are a reflection of periods of American architecture. See Figure 1.



The Office of the Architect of the Capitol (AOC) is responsible to the United States Congress for the maintenance, operation, development and preservation of the United States Capitol complex. No small part of this responsibility includes ensuring the safety of Congress and other building occupants, as well as preservation of the buildings, from the effects of fire.


Fires have played a significant role in the construction history of the Capitol complex, the most memorable fire being the burning of the Capitol and other public buildings by British troops in August 1814 that left Washington in ruins. One of the most significant, in terms of resulting fire protection, was the Library of Congress fire of 1826. At that time, the Library of Congress was housed within the Capitol. While the fire, caused by an unattended candle, did not do an extensive amount of damage, those fighting the fire (Sam Houston and Daniel Webster included) realized that it came very close to involving the then-wooden roof structure. The resulting philosophy included moving heating fuels (coal and wood) away from the building and the provision of a dedicated water supply. A more devastating fire in 1851 destroyed the Library reading room and its contents, and resulted in a "fireproof" fit-out that included the first cast iron ceiling in America. That ceiling was a precursor to the most famous fire protection feature on Capitol Hill – the cast iron dome. This unique feature of the Capitol became a symbol of the U.S. legislative branch and America itself when it replaced the original wooden dome that one member of Congress considered, "a nest of dry materials...that seems to almost threaten conflagration."1 A 1988 fire in the Longworth House Office Building was the impetus for the installation of new fire alarm systems in all of the major buildings.



From a fire protection and life safety perspective, the AOC follows a General Services Administration model and enforces the International Building Code (IBC), but replaces the egress provisions of Chapter 10 with the requirements of NFPA 101. This is a recent change in philosophy on Capitol Hill, as historically the Legislative Branch was under no legal obligation to follow fire protection or building standards. The AOC maintains a set of design standards that form the applicable set of codes, currently referencing the 2003 editions of the IBC and NFPA 101.

These Design Standards require complete sprinkler protection for all new construction, including renovation projects, and the AOC aims for full smoke detection as well. For example, the new 580,000-square foot (54,000 m2), underground Capitol Visitor Center is provided with complete sprinkler protection and approximately 2,000 smoke detectors. The fire marshal division is currently performing acceptance testing of the life safety systems of this new facility, which is scheduled to be completed in November of this year.



Like most fire protection professionals, those at the AOC have no shortage of challenges to providing appropriate levels of fire protection. There are some resource and functional constraints, but the most prevalent challenge is integrating fire protection and life safety features into these buildings without significantly altering the historic fabric.


During the late 1990s and early 2000s, large portions of Congressional space were provided with automatic sprinkler protection. This provision greatly enhanced the level of life safety and asset protection across the entire Capitol complex. The period saw protection added to the majority of back of house areas, offices, corridors and most of the ornate committee meeting rooms. Some spaces were left out; however, typically due to lack of space to route piping. Sprinkler protection is now being provided in these final spaces for the majority of the large buildings. Some of this work is accomplished as committee rooms or other significant spaces are renovated, but most of this work specifically provides this important protection.


One example of this specific work is in the lowest level of the Cannon House Office Building Rotunda. The ceiling of this area is constructed of a historically significant Guastavino tile system, making exposed sprinklers and piping undesirable. The original building drawings did not depict the conditions above this ceiling, leaving the AOC fire protection engineers to guess at whether there was void or construction fill in the space. In-house construction forces breached the three-foot-thick (one meter) masonry wall surrounding the space, which allowed AOC staff to view the complex system of tile arches that supported the 60-foot (18 meters) span of the main Rotunda floor. Adequate void space was available for providing sprinkler piping, and concealed sprinklers were utilized to protect the floor below the ceiling with minimal disturbance to this unique construction feature (see Figure 2). Other examples of integrating fire protection features into the historic fabric, and the associated level of effort required to do so, are shown in Figures 3 through 6.


Around the same time that the sprinkler systems were being installed in the buildings, a mass effort was begun to provide fire alarm systems in all of the major buildings. These systems greatly improved the level of life safety over the Capitol complex with notification throughout public areas and smoke detection throughout the majority of spaces. Unfortunately, these systems are now reaching the end of their lifespans, and spare parts and service support are increasingly difficult to obtain. New addressable system designs are being completed and some construction contracts are in place to provide replacement of the existing zoned systems. These new systems will provide audible and visible notification, as well as smoke detection throughout the buildings, and provide rapid and concise information about potential incidents and evacuation of building occupants.


The final and perhaps greatest fire protection challenge deals with egress. Many of the buildings on Capitol Hill were built prior to the development of modern building and life safety codes. Even those constructed following the development of such codes were not subject to them. Much work has been done to determine an appropriate response to the non-compliant egress systems in the major buildings. The work has included performance-based designs with significant levels of fire modeling, prescriptive-based designs that significantly alter the building structure to comply directly with the NFPA 101, and engineering judgment. Solutions to the deficiencies vary and have included adding stairs to the exteriors, demolishing interior space and adding interior stairs, providing horizontal exits, and enclosing existing open stairs. Through this combination of efforts, conceptual designs for the egress systems in the majority of the significant buildings have been developed over the past few years, and construction has begun on some of these projects.

Michael L. Edwards, P.E., is with the Architect of the Capitol.

1Allen, William C. History of the United States Capitol. Washington: 106th Congress, Government Printing Office, 2001.

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