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
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
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.
FIRE PROTECTION ACCOMPLISHMENTS
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
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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