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Building Projects


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Current Projects

Before cleaning and after cleaning picture of the Capitol Building.

Photo credit: the Legislative Support Services Video Department
and Legislative Support Services Supply & Facilities

Dome Cleaning

Masonry preservation work on the Legislative Building is complete. Cleaning and masonry repair work was performed from the top down to the entire building.  

The Legislature approved $3.4 million for the work in early 2018. The statute authorizing the work also allows for repairs to other exterior features of the building.

In the spring of 2019, repairs will be made to various building:

  • Windows
  • Doors
  • Skylights (those over the Mother Joseph statue and the plaza walkway)

Video courtesy of Legislative Support Services and Dave Whitmore

Consultant team

Enterprise Services contracted with a consulting team and masonry firm to perform the 2018 work following a competitive bidding process:

  • SHKS Architects of Seattle completed design work for the project in August, and worked on an ongoing basis to develop solutions for repairs as more was discovered about the building’s condition during cleaning. 
  • Pioneer Masonry of Seattle performed the cleaning and restoration work.

Portland-based conservators ARG also provided expertise throughout the project. Enterprise Services contracts conservators because their expertise is vital to each project performed on campus historic buildings.

Work Cycle

Masonry preservation work on the Legislative Building's dome, which includes cleaning, is generally performed about every seven years. The dome's darkened appearance is from a lichen that grows on the sandstone. The growth is a natural occurrence in the northwest and typically reappears within five to six years of cleaning.

Cleaning and preservation work go hand-in-hand. Not only would it be cost prohibitive to perform cleaning and preservation separately, cleaning without preservation work raises risk for water seeping into joints between the sandstone once lichen growth is removed. Cleaning also:

  • Helps reveal areas where mortar between joints is failing or where the stone may be damaged
  • Creates a clean surface so that the mortar can be replaced and sandstone may be repaired
  • Removes lichen that can lead to standstone deterioration if not periodically washed off
  • Improves the appearance of the building

The science behind masonry preservation

There is considerable science is involved in the preservation and cleaning materials like sandstone -- and the science as well as best practices are continually evolving.

In the past, the dome was cleaned with:

  • High water pressure
  • A cleaning agent that inhibits lichen growth
  • Chemical water repellants

Over time, it has become apparent that high pressure and water repellants degrade historic stone surfaces.

Preservation work was performed in 2012 at a cost of $3 million.  At the time, no cleaning agents were used.  This may have led to a faster reappearance of lichen and a darker-than-usual appearance of the dome.

The 2018 cleaning sought to strike a balance by utilizing:

  • Low water pressure
  • Combined with gentle cleaning agents

Enterprise Services is committed to testing and evaluating new products and emerging technologies in conjunction with natural stone preservation experts.


Frequently Asked Questions

Q: Can you put a coating on the dome so that it doesn’t darken in color as quickly (such as a sealant)?

A: Some coatings act like sealants and can trap moisture inside the stone, leading to damage during freeze and thaw cycles. Other products tested in the past cause discoloration. 

Enterprise Services works closely with preservation experts to test products for use on the building’s sandstone.  A somewhat conservative approach to using products for treatment and preservation is necessary to maintain the quality of the historic stone.  

Q: Why do you have to re-examine the cleaning process each time?

A: The science as well as best practices are continually evolving for cleaning materials like sandstone. We always work with historic preservation consultants to plan and implement cleaning and preservation work so that the latest science and best practices are utilized.

Q: Did Enterprise Services use a cleansing agent on the dome in 2018?

Yes, D-2 was used to break down the organic growth on the building. It is a gentler way to clean the lichen off the building than high-pressure power washing. The cleaning used a combination of D-2 and high-temperature, low-pressure washing. There were two applications of D-2 on the building – one that was rinsed off, and one that was not.

D-2 is a biodegradable liquid that removes stains from stone, such as those caused by lichen, other growth and pollutants. D2 was selected after careful consideration of numerous products.


Past Projects

Masonry and cleaning work was last done on the Legislative Building Dome in 2012

Historic Buildings Exterior Repairs Project

The West Campus Historic Buildings Exterior Repairs project includes repair and preservation work on the Cherberg, Legislative, Temple of Justice, Insurance, Pritchard and O'Brien buildings. Project work includes a condition assessment, preservation plan, and design and construction for repairs to the buildings. The work also includes cleaning, which is needed to detect masonry defects and repair needs.

  • Cleaning of the building's stairs, plaza deck and plinths was completed in April, 2017.
  • Masonry repairs to the legislative stairs and plaza were completed in 2017.

Water Leaks

  • Work on a new metal roof above the State Reception Room, where there was an active leak, was completed in December, 2016. Prior to the work, the only cover over this portion of the building was exposed sandstone. The new roof was part of a larger West Campus Exteriors project.
  • In addition to exterior repairs project work, DES completed an emergency repair in January, 2017, to fix multiple leak locations in the building's southwest corner parapet walls and caps.
  • In May of 2017 Enterprise Services authorized use of an unmanned aircraft system (UAS) on the Capitol Campus to make detailed observations of the roof of the historic Legislative Building that it would be difficult and expensive to safely access in person. A DES contractor used the UAS to examine the Legislative Building roof for possible defects and points of failure to identify where water is penetrating the building's mini-dome and causing damage. Enterprise Services is now in the process of developing a scope of work for temporary repairs to the building. More extensive repairs would be incorporated into a future project to clean the dome and make masonry repairs, and are dependent on future funding.
  • Learn more about steps Enterprise Services is taking to address water leaks in state-owned buildings.


  • 1949 – Seismic upgrade and repairs following the 1949 earthquake. Stone lantern at the dome's cupolas replaced with a metal one. Cupola also reinforced with steel in the columns, cornice and sides of the arches.
  • 1956 – Elevator upgrades, including replacement of original bronze grille doors, rebuilding of cabs, and updates to operating equipment.
  • 1973 – Major structural upgrade installed concrete shear walls in select locations. Air conditioning system added, requiring installation of acoustical drop ceiling in most perimeter offices.
  • 1974-1975 – ADA upgrades, including conversion of private southeast corner entrance to a public, universally acceptable entrance.
  • 1985 – Realization of original decorative paint schemes in Rotunda, House and Senate Chambers, as well as some elected officials' offices. Plaster repairs. New metal railings installed in galleries. General cleaning of marble and bronze elements.
  • 2002-2004 - Major rehabilitation that included earthquake upgrades, as well as upgrades to systems, fire protection, accessibility, and a general infrastructure overhaul.
  • 2012-2013 - Extensive dome cleaning and sandstone repair project.

Building History

Washington State's Legislative Building, often referred to as the Capitol Building, was completed in 1928 after six years of construction. It consists of 255,564 gross square feet and is comprised of more than 173 million pounds of stone, brick, concrete and steel.

The Legislative Building houses the two chambers of the state legislature and offices of several elected officials, including the governor. The structure consists of four floors with the dome at the center. The Legislative Building was added to the National Register of Historic Properties in 1979.

Wilder and White

The Legislative Building is the centerpiece of the five historic capitol buildings designed by New York architects Walter Wilder and Harry White. Conceived in an architectural competition in 1911, and selected by the State Capitol Commission, Wilder and White's designs for the Legislative building were completed and set into implementation in 1922.

The building is the dominant feature of the capitol grounds, with its dome 287 feet (87m) high, making it the tallest self-supporting masonry dome in the United States and fifth tallest masonry dome in the world. A number of features in the structure commemorates Washington's addition to the Union as the 42nd state: 42 steps lead to the building's north entrance, and one of the four 42-star flags owned by the State are displayed in the State Reception Room.

The basic floor plan of the Legislative Building is simple, formal and symmetrical. There is a square, central section of four floors, surmounted by a domain. The Rotunda under the dome contains eminent public space above the first floor, with the tall, open space above it soaring 174 feet from the floor to the top of the interior dome. Rectangular wings of equal size on the east and west flank the central sections, and contain House and Senate activities, as well as offices for elected officials.

More information