The enclosure is nearly circular, measuring just over twenty-seven metres north to south and twenty-six and a half metres east to west, and its bank reaches only about sixty centimetres in height. What makes the geometry quietly interesting is that the boundary does not behave the same way all around: for roughly the northern-to-southwestern arc, the bank rises above a level interior, while for the remaining arc from southwest back to north, it presents an inward-facing scarp instead, because the ground outside is higher there. The site reads the contours of its north-facing slope rather than ignoring them.

A rath is a ringfort, the most common field monument in Ireland, typically a circular enclosure of the early medieval period, roughly the fifth to twelfth centuries, used as a defended farmstead for a single family and their livestock. Most were defined by one or more earthen banks and ditches; the Barradaw example, modest in scale and now set among tillage, belongs to that broad and numerous class. The interior is level, which would have suited the domestic activity such enclosures once contained, though today reeds colonise the eastern half, a sign of wet ground beneath. The southwestern side has been clipped by a drain, a small but irreversible alteration that speaks to centuries of agricultural pressure on monuments that were never especially imposing to begin with.