Throughout the time span of a century or so, the evolution of the house design style in the Pacific Northwest has maintained a few common characters as a response to the climatic and geographic contexts. Whether it is a gable roof with protruding eave, or a flat roof with a separately attached overhang, or a sculptural form with shelter carved out of the massing, the successive generations along the historic timeline all try to address the same challenge posed by the regional climate. The physical environment has barely shifted, yet the design philosophies have evolved under the environmental pressure from the larger global trend.