Cereal-producing farms needed separate storage buildings for the threshed grain or fodder which also needed to be kept out of reach of vermin, especially rats. In the corn-growing south of England free-standing granaries were built from the fifteenth century, not only to store corn for sale but also for seed. Granaries needed to be well ventilated and their walls sealed against infestation by insects. They were therefore raised on mushroom-shaped staddle stones, had removable steps, and the floors inside were made of seasoned and fitted planks. Granary doors often had cat holes enabling the farm cat to catch rodents. Because of their comparatively small size and because the staddle stones are valued as decorative garden features, granaries have been particularly vulnerable to demolition and salvage.