Llwyn Isa is recorded in the Tithe Survey as a farm owned by Sir Watkins Williams Wynn, an outlying holding therefore on the Wynnstay estate. The farmhouse was rebuilt in the late C19, but this range of C18/early C19 farm buildings to its north-west was retained. They appear to be substantially of one date, and suggest the hand of an improving landlord.

A range of multi-purpose farm buildings standing on rising ground. The range is built in rubble masonry with slate roof and tile ridge, including a short forward return wing at each end. The main range has a large heck-door at left and four other doors and one window; above are two granary doors with raking dormers. Timber lintels throughout.

The wing at left has a first unit the roof of which is level with the main range roof. This first unit has a window below eaves and another granary door with raking dormer, at the head of a flight of stone steps. Below is a large cartshed opening, with a very large timber lintel, partly blocked by later stonework. The left wing continues with a double width cartshed.

The right wing consists of a cartshed the roof apex of which lines with the eaves of the main range. It terminates with a pigsty entered from the gable end where there are two small walled yards.