The most important building of the farmstead was the barn, for threshing out the grain and storing both the unthreshed sheaves and the threshed straw. Two of the barns at the Museum, from Hambrook and Lee-on-Solent, are from the coastal plain and are similar in form, having end and side aisles to maximise storage space. The third, from Cowfold, has no aisles; it is from the Weald, where arable acreages were generally smaller than on the Downs or the coastal plain.

Barns from the medieval period, such as the one from Cowfold, survive in fairly large numbers, but most other farm buildings are later in date. There must have been cattle sheds and cartsheds on medieval farms, but they were not built well enough to last until the present day, and most of the surviving examples date from the 18th and 19th centuries. Most granaries are also post-medieval, but for a different reason — before the 17th century, valuable farm produce such as grain and apples was normally kept within the house, often in a loft or attic.

The three granaries re-erected in the Museum date from the 18th and 19th centuries. They differ mainly in size, ranging from the tiny granary from West Ashling (next to the Lurgashall mill) which stands on only five staddle stones, to the Littlehampton granary which stands on sixteen. Three shelter sheds for cattle can be seen at the Museum, although not yet with associated foldyards, and a stable and wagon shed form a group with the barn from Lee-on-Solent.

In due course it is intended that all the farm buildings re-erected at the Museum will form self-contained farmstead groups. The first such group has been established with Bayleaf and the barn from Cowfold, consisting of a foldyard, shelters for carts and cattle, and all the ancillary buildings and fences necessary for a working farmstead.