The style and placement of the sheathing boards on Vermont barns can be helpful in identifying the date of construction. Following is a discussion of some important markers in the evolution of sheathing materials.
Until the 1800s, most New England barns were covered in wide, vertically hung, rough-sawn boards. The boards were still wet (or "green") when they were installed. When the boards dried, they would shrink and leave slats for ventilation.
By the 1830s and 1840s, farmers attempted to tighten the walls of their barns. On existing barns, thin, rough-sawn boards were tacked between the vertical sheathing boards, on the inside of the barn, to cover the open slats and insulate the barn. Newly constructed barns were given two layers of vertical sheathing boards - half inch thick, rough-sawn boards covered by one inch thick boards. Often the walls were further tightened with an outer layer of pine shingles, as seen in the image below.
In the mid-19th century, board-and-batten siding was a common alternative to wood shingles. Vertical board sheathing boards were hung, and vertical battens were nailed over the gaps between the boards. Notice in the image below the raised narrow boards interspersed between the wide, flat boards.
By the 1860s, wood clapboards (horizontally placed, overlapping boards) were growing in popularity and remained a fashionable sheathing material until the 1920s and 1930s. Clapboard barns were typically painted red with white trim.
After the 1920s, novelty siding was used as a cheaper alternative to clapboards. The walls of the barn were covered with boards, and a beveled edge was carved into the wood to create the illusion of individually hung clapboards, as seen below.