I have a 1915 20'x30' rectangular stick built home in southern Colo. The attic is maybe 2 1/2' high at its peak. There is a vent at each end of the attic plus 3 roof vents along the top. I can understand them being open in summer, but should they be covered/closed somehow in the winter? If so, do i crawl up into the attic and cover each hole with a board or something?
Yes, attic ventilation still applies in the winter. Primarily to alleviate the humidity contained in the contained air, which also would be preventative action to lessen the potential for attic mold beginning to take place.