Before the 1850s, the main doors of most Vermont barns consisted of a pair of large hinged doors that opened onto the main drive floor. These doors were constructed of vertical boards with diagonal braces and were hung from large wrought iron straps. Note the diagonal braces on the interior of the hinged doors in the image on the left and the wrought iron straps (visible near the top of the door) in the image on the right.
Sliding doors were installed on barns by the mid-19th century. Tracks were constructed on the exterior of the barn, and the doors were hung on wheels that rolled along the track as the door slid open. The image on the left demonstrates the track system of the sliding door, while the image on the right illustrates a full view of the sliding doors.
After the 1850s, most barn doors were made of planed, tongue-and-groove boards placed diagonally, as seen in the images below.
In the late 19th and early 20th centuries, haymow doors were often installed in the peak of the gable end, as seen on the left side of the barn in the image below.