Lower Castle O'Trim Farmhouse and Barn Adjoining to South

Lower Castle O' Trim Farmhouse, built in 1711, is a two-storey house with an end baffle-entry plan, constructed from pebbledashed rubble and topped with a slate roof. The house features three bays, with windows that are rebated and chamfered, although some originally had mullions; only one mullion remains in the second and third bays on the first floor. The left-hand first floor window has one light. There is an inserted doorway with plain reveals to the left of the third bay, while the original doorway in the left-hand bay has a moulded surround and a battlemented lintel inscribed with 'G[T]M 1711'. The house has gable chimneys. Inside, the baffle remains, along with a firehood bressumer, two chamfered and stopped axial beams, and a spice cupboard recess with a moulded surround.

Adjoining the farmhouse to the south is a barn, likely built in the late 18th century, which has exposed rubble walls. The wider shippon end on the right features a recessed wide entrance with plain reveals, while the left side has a pitching hole. At the far left, next to the house, there is a door with a chamfered surround and a pitching door above it.