The wide arched recess at its base, nearly four metres across and two and a half metres deep, would once have been where the burned lime was raked out after firing. A stoking-hole is still evident, and a ramp survives at the rear, which would have allowed workers to load limestone and fuel in from above.

A lime kiln is essentially a large stone furnace, built to burn limestone at high temperatures until it breaks down into quicklime, a material used widely in agriculture to reduce soil acidity and in construction as a binding agent for mortar. This example at Ballyerra was in use in the early 1900s, according to local memory, placing it in the last generation of traditional lime-burning in Ireland before industrial alternatives displaced the practice. The sides of the kiln have since collapsed inward, forming a low mound roughly two metres high on either flank, which gives the structure a somewhat sunken, earthen appearance from a distance, easily mistaken for a natural feature of the landscape.