Where the masonry has given way, the internal funnel is exposed, roughly two metres in diameter, brick-lined at its base and stone-lined further up. It is the kind of accidental cross-section that no intact building could provide.

Lime kilns were once a fixture of the Irish rural economy. Limestone was loaded in at the top, fuel added, and the resulting quicklime drawn off from the bottom to be spread on acidic farmland or used in mortar and whitewash. The Carrigacrump kiln is a substantial example of the type. The west-facing front wall stands around ten metres high and nearly six metres wide, with an arched recess at ground level, roughly square in its proportions, where workers would have raked out the burnt lime. The rear of this recess is lintelled rather than arched, a small but telling detail about how the structure was assembled from two different constructional approaches. A long ramp, twenty-nine metres in length, approaches from the east side, allowing carts or barrows to reach the kiln's upper opening with loads of raw limestone from the quarry directly behind. The north side of the structure is revetted and buttressed against the hillside, and a stone wall, still about two metres high, encloses the top of the kiln, with a single opening, or ope, on the west face.