Once upon a time, the American countryside was dotted with round barns. A round barn is a historic structure that could be circular or containing more than four sides. There are round barns existent on the working farms at Colonial Williamsburg. Over the years, round barns have fallen out of favor with the growth of their square-sided counterparts. However, a resurgence of older farming techniques has led to a return of the round barn design.
When round barns were constructed, they were generally thought to be less expensive to build and more labor saving than their rectangular cousins. Early barns built in the circular design were done so in order to house threshing machines in the haymow. These barns were constructed on multiple levels. Cattle on the lowest floor were hitched to the machine and turned it by pulling levers in a circle around the edges of the building, while on upper floors, the machine operated. The threshed grain or hay stored in the haymow could be dropped into wagons waiting on lower floors, and these wagons could be driven away without having to be turned. Additonally, livestock housed in a round barn could be turned so that they faced the wall and were forced to relieve themselves at the center of the room. This made the animal wastes easier to clean up, since they were all in one central spot.
Today, circular barns have many practical uses. A circular barn can be transformed into an exercise arena for horse, or segmented into 'slices' for animal stalls. A round barn is thought to be a safer structure for high wind conditions, due to the circular nature of the building. Materials generally used for round barns include stone, wood or tin over a wooden frame. A foundation may be poured of concrete. The roof is generally shingled as a house would be.
Historical records of round barn construction indicate that the foundation would be poured a year in advance because it took so long to construct the forms for pouring the concrete. The frame was made from green elm wood soaked in water and then bent in a curved shape. The roof trusses slanted lengthwise away from a central pillar. Over this a decking and shingles were placed. According to the website Roundbarn Homestead.com, a round barn's construction took 4-6 carpenters working 6 days a week an average 4 months to build.