What is a cupola?
A cupola is a small tower or dome-like feature projecting from the top of a barn roof. Ranging from large and ornate to small and simple, cupolas typically have three parts: the base, the vents and the cap. The size of the base is determined by the slope or pitch of the barn roof. In the middle, the vents can be windows or slats designed to let light, air or gas pass through. Screens can be added to keep out insects and animals. The caps of cupolas are usually designed to have a square, octagonal, bell-like or other distinctive geometric shape. They are also often topped with a finial or weathervane.
Why do barns need cupolas?
As noted by Thomas Durant Visser in his excellent Field Guide to New England Barns and Farm Buildings, to reduce the amount of feed required by the animals during the winter, some farmers recommended that barns should be built with battens nailed over the cracks between the sheathing boards to reduce drafts, while others covered their barn walls with wooden shingles or clapboards. But farmers soon found that tight barns could lead to problems.
As one farmer observed in 1852: The breath from cattle, together with the vapor arising from the manure, which defies all attempts to keep it below the floor if the cellar is warm, covers, not only the floor over the cellar, but the beams, and the whole underside of the roof, with pearly trickling drops for weeks together during the winter. If the doors are thrown open in order to evaporate this moisture, you lose the benefits you have been seeking in making a tight barn, by reducing the temperature so much that cattle require more food, while the effect is to reduce the flow of milk in the cows. . . . Many large and valuable barns have been very much damaged by being placed over a manure cellar without proper ventilation.
To remedy this problem, farmers began installing ventilators, known in New England as cupolas, over an opening left in the center of the top of the barn. The first ventilators were simple wooden louvered boxes with gable roofs, mounted near the ridge of the barn. Several of our Madison barns have more ornate cupolas. Note the fancy shingle patterns on the Samuel Gilman barn built by Zantford Savary in 1903.