I'm not really sure if it qualifies as a vernacular building type, but because so much of Colorado was settled from the East at the height of the use of the Victorian style in architecture, there are many older buildings of this type throughout the Front Range and western mountains. These buildings are so ubiquitous that they are often referenced implicitly and explicitly by new developments all over the state as the only architectural style of traditional building.
What is known here as "mountain Victorian" is not the painted-lady style of high-Victorian residential design you see in San Francisco or even the overly fussy, carpenter gothic style Victorians in my native Kentucky. The style here was simplified, maybe because of the lack of skilled craftsmen or the paucity of building materials. However, even though the Colorado version may be "simplified", these buildings are some of the most ebullient and expressive construction to be found.
Like most Victorian era residential buildings they are not so tightly constrained by a series of rules of style as they are designed to be picturesque. What is common among most of these buildings, predominantly houses, is the multi-colored paint schemes and variety of siding types.
And of course, all of these mountain Victorian houses display the strongly vertical proportion of both windows and building elements. Their often complicated roofs freely combine gables, hips and mansards.
What makes these buildings such a difficult fit for Colorado is the relatively small eaves and roof overhangs do not come close to shading the tall windows from the onslaught of the sun. To their credit, very many of the buildings have white painted wood siding and do not have significant heat gain on their vertical surfaces.
Like so many examples of architectural imperialism, the imported style has little or nothing to do with local building traditions or conditions. However, over time, and by force of numbers, these mountain Victorians have become a part of the high country landscape and the most copied and bastardized form of vernacular architecture of the region.