The three-story building is designed in the Italianate style with classical, restrained architectural details.
The original building measures roughly 118 feet (east and west facades) by 66 feet (north and south facades). The 1905 expansion brought the overall dimensions to 118 feet by 116 feet (north and south facades).
The foundation is rusticated Chuckanut (Washington State) sandstone, yellow in color with a coarse-grained texture. The stone foundation is topped with brick masonry load-bearing walls that are veneered with Chuckanut sandstone on the exterior. The original portion of the building uses an arch and vault type of construction.
Structural Systems and Framing
Sandstone and basalt were used for the original basement walls, which are more than four feet thick in places. The brick in the masonry load-bearing walls was fired locally. Timber and iron members give internal support. The timber-spanning members are old growth from Oregon forests. The octagonal cupola is wood cladding over wood framing.
The upper stories are composed of smooth Tenino (Washington State) sandstone. The masonry is laid in a broken ashlar pattern with a Tenino sandstone cap. The north and south facades are virtually identical, but the east and west facades vary greatly from each other as a result of the 1905 alterations. The center three bays of the east facade project slightly and are capped with classical pediments. The first story has rusticated pilasters that terminate in a belt cornice and segmental arch openings, both of which rest on the low building base. The second and third stories are grouped and defined by
Roman Doric pilasters and entablatures. The tall, narrow windows of the second story are headed with a projecting cornice supported by consoles, while those of the third story are square openings with frame moldings.
The eight stone chimneys are original. They were, however, fitted with rebar and filled with concrete in the 1970s rehabilitation. At the same time, the exterior surfaces were treated with an epoxy to deter erosion of the stone, and the openings were capped in sheet metal.
Doorways and Doors
Exterior granite stairs lead to landings at each of the four sets of entry doors, one set on each facade. East and west entries are centered in their facade. The west entry is set back under a canopy overhang and is the main entrance to the building. North and south entries are set off-center toward the west. Bronze handrails flank each stairway. The exterior double doors are varnished oak with upper light panels. Fixed two-light transoms top the doors. Door hardware is unlacquered bronze.
Window sashes are a combination of casement, double-hung, and fixed types. The second story has tall double-hung windows topped with braced pediments. The third story has casement-type openings with flat pediments. Cupola windows are round-arched fixed, double- hung sash.
The Pioneer Courthouse has an intersecting hip and gable roof. The cornice has dentils evenly spaced below flat and gabled eaves. The cupola roof is wood, clad in copper, with a hatch-type door that provides access to the flagpole.