Plan and Shape. The earliest barns in San Juan County, as elsewhere in the region, had English or center drive plans. In timber frame construction, a series of four bents made a barn of three bays, with entries in the center of each side and mows on either side; this center drive, or an area off of it, was used as a threshing floor. Barns were oriented to take advantage of prevailing winds that would blow through the open doorways of the center drive and remove the chaff from the threshed grain. The threshed grain was stored in bins near the floor, and hay was stored in the mows; sometimes sheds or lean-tos were added for animal stables. Barns were built into hillsides to form a ‘bank barn’, with the upper portion accessed by the center drive with hay mows on either side, and separate, down slope entrance for stalls for horses, beef cattle, or dairy.
A later plan was that of the ‘western’ barn, with an entry in the gable end for a center aisle with mow in the middle and stalls on either side. These were often post-and-beam construction, creating a large open space in the middle, where the mow extended from floor (usually unfinished, i.e. dirt) all the way to the roof. At first hay was forked from wagons by hand; later, the introduction of the hay track introduced limitations on the width of the barn, which ranged from 20-36’, most common being 34-36’ because it allowed from two rows of stalls with feed alleys and hay loft above (with standardization).
Lofts were a later introduction through frame roof truss systems, which added volume by means of several new roof shapes: gambrel (English and Dutch), gothic arch, and bow. On the ground floor, a 4-6’ wide feed alley (for carts) separated two rows of stalls, usually with stanchions for dairy cows.