Dairying continued to expand and the form of buildings accommodated the change. The most profound modification toward the end of the 19th century was the development of the tower silo. These sentinel-like structures enabled green fodder to be stored and fed out during the winter months. Previously, cows had to be fed on dry grain and hay with the result that they dried up and could not be milked. Feeding green fodder permitted milking all year long, satisfying the growing demands of expanding urban populations.
Another barn addition was the milk house, a small, sanitary building to house freshly produced milk in cool environment, and running water to cleanse empty containers. The first milk storage facilities were inside barns, but by the 1940s state regulations required an outside and separate structure. These small, rectangular barn appendages have become standard features of all barn types.
Finally the Raised or Basement barn itself was modified by the addition of a two floor straw shed at right angles to the existing barn (Noble 1974, 14). The basement level permitted herds to grow by offering additional stanchion space. In the early decades of the 20th Century different roof types were popularized in order to increase the loft capacity to store even more hay and straw for growing herds. The gambrel roof became most widely adopted. Round roof or Gothic types were tried, but never became widely popular because they required expensive rafter systems of curving design. Many farmers, however, continued to employ the gable roof, even in new construction.