The ruin at Kilcash, in south Tipperary, sits on a south-facing slope with Slievenamon rising to the north, and it preserves, in its fragmentary stonework, a surprisingly legible account of how the house was built and finished. The 17th-century house was constructed directly against the west wall of an existing tower house, the kind of tall, defensive medieval structure common across Ireland, and the two were joined by cutting a doorway through the tower's second-floor wall to give access to the attic of the newer building. Where the window surrounds still survive, they are cut limestone, chamfered on the outside with punch tooling and drafted margins. Patches of original plaster remain around some openings, showing a block-and-start pattern, a decorative technique fashionable across the 17th century in which false stone joints were painted or moulded onto the plaster surface to give the impression of dressed ashlar. Beam-holes at parapet level suggest the eaves were finished with a projecting wooden cornice, now long gone.

The history of the site runs back well before the house itself was built. The manor passed from the de Valle family into the hands of the Ormonde Butlers between 1538 and 1545, and was mentioned in the will of James Butler, the 9th Earl of Ormonde, in 1545. It became the seat of a junior branch of the Butler family from 1639, but by the time of the Civil Survey of 1654 to 1656, the castle and dwelling-house already had their roof and lofts burnt, with only a bawn, a walled enclosure offering basic defence, and various thatched outbuildings remaining. Recovery followed: the Hearth Money Records of 1665 to 1667 show Richard Butler being taxed for three fireplaces, and by 1677 the property was being called his mansion house. That recovery proved temporary. When John Butler became de jure 15th Earl of Ormonde in 1758, the castle began its long decline. Around 1800, Walter Butler, the 18th Earl, sold the building materials, described as being for a trifling consideration, to a merchant from Carrick-on-Suir named James Power. The systematic stripping of the site for salvage explains why so little survives, and why what does remain reads almost as an anatomy lesson, the floors gone, the corbels that held them still projecting from the walls, the window heads and sills removed, the stonework itself left as a kind of index of a vanished interior.