Sweathouses were a distinctly Irish form of therapeutic structure, used much like a sauna: a fire would be lit inside to heat the stones, the embers raked out, and a person would crawl in through the low entrance to sweat out ailments ranging from rheumatism to fever. The one at Cartronaglogh is modest even by the standards of the type, its interior measuring roughly two metres by one and a half, with a roof that has largely collapsed, leaving walls still standing to somewhere between one and one point two metres.

The structure was built directly into the hillslope, a common technique that used the surrounding earth for insulation. Its entrance, now destroyed, faced south-west and was approached by a trench cut into the hill, between two and a half and four metres long and less than a metre and a half wide, just enough to allow a person to approach low and enter. What makes the Cartronaglogh sweathouse quietly telling is its context: by the time the Ordnance Survey recorded it on their 1914 six-inch map, deserted houses already stood roughly 150 metres to the south and west. The community that built and used this structure had gone, leaving the sweathouse as one of the few legible traces of a settled life on this stretch of mountain. Whether those houses were abandoned during or after the Famine years, or earlier, the notes do not say, but the proximity is hard to ignore.

The site now sits within plantation forestry, which makes casual discovery unlikely. The trench approach and the collapsed roof mean the chamber reads more as a shallow earthwork than a building from any distance, and a visitor unfamiliar with the form might pass it without registering what it is.