Threshing barn on the north side of farmyard at Middle Culham Farm

Threshing barn on the north side of farmyard at Middle Culham Farm

This threshing barn was constructed in the mid to late 19th century on a site where an earlier building, dating to the 18th century or earlier, had previously stood. The 19th-century barn incorporates substantial timber-framing salvaged from that earlier structure.

The barn is constructed with a timber frame clad in weatherboarding, set on a brick plinth (partially rendered) and topped with clay tile roofs. It has a roughly rectangular footprint oriented east-west, built in two halves at different levels, with the west end standing higher than the east end. Each half has a half-hipped roof at its east and west ends. A pair of porches flanks the north side, with the west porch featuring a gable roof and the east porch hipped. On either side of the porches are lean-to stores with stable doors, louvered windows, and slate roofs. The south elevation contains a pair of large barn doors positioned opposite the north porches, while the west elevation includes a window hatch.

Internally, the barn comprises six bays—three within the higher west end and three in the lower east end. Opposing threshing barn openings are located in the central bay of each half, with timber-plank threshing floors stretching between them. Steps lead down from the upper west level to the lower east level.

The internal timber frame incorporates a large quantity of reused timbers from the earlier barn, including just over half of the principal jowl posts. Most tie beams are substantial timbers supported by curved braces springing from the posts, with at least two curved braces between post and wall plates. The queen-post roof includes posts and collars largely of early timber; at least one collar is cambered. The principal rafters combine early rough-hewn timbers with 19th-century work. Other early reused elements include the majority of two rows of lap-jointed clasped purlins, though some sections have been replaced with thinner 19th-century timber. Common rafters and ridge beams are mostly 19th century or later. Early timber also appears in principal wall frame elements—substantial wall plates, mid-rails, and sill plates. Most wall studs and straight bracing are 19th-century timber, though some thicker earlier studs have been reused throughout the building's length. A small number of early timbers contain empty mortices suggesting they are no longer serving their original structural function. Carpenters' marks are visible on some reused timbers, predominantly Roman numerals with at least two marked by letters; these are mostly located at joints and many correspond with connected timbers.

The west porch incorporates early timber framing including wall plate, mid-rail, sill plate, curved wall braces, and a queen-post truss within the gable end. The east hipped-roof porch retains some early timber fragments, but its roof and wall frame are largely 19th-century construction.

The lean-to stores on the north side date to the mid-19th century and have brick-tile floors. Parts of their roof structure and walls were replaced in the latter half of the 20th and early 21st centuries. The eastern lean-to, with attached railings, appears to have been most recently used as a kennel.