The chancel arch, cut from sandstone and chamfered along its edges, still stands in good condition despite everything around it having fallen away or softened under ivy. Slots cut into both inner faces of the arch once held a rood screen, the timber partition that separated the nave, where the congregation stood, from the chancel reserved for the clergy. That detail, small and easy to miss, speaks to a building that was once carefully ordered and in regular use. Fragments of slate roof tiles still lie near the north-east angle of the nave interior, the last physical trace of a roof that has long since gone.

The arch is the key to dating the building. Scholars have placed its construction in the early thirteenth century, identifying the arch as Transitional in style, a term referring to the period when Irish ecclesiastical architecture was moving from the rounded forms of Romanesque towards the pointed profiles of Gothic. The church itself is a two-cell structure of nave and chancel, built from a mixture of limestone and sandstone rubble laid in well-coursed courses, with walls between 0.7 and 0.86 metres thick. The south wall of the nave shows a pronounced inward lean that turns out to be the result of later rebuilding, keyed into a buttress at the south end of the west gable rather than original construction. The Civil Survey of 1654 to 1656 records the glebeland of the Vicar of the Parish of Derragrath as lying west of the church, suggesting the site remained a functioning parish centre well into the seventeenth century. A ringfort sits roughly a hundred metres to the north, a reminder that the rise on which the church stands had been a place of some significance long before any Christian building was put there.

The graveyard surrounding the church is still accessible from the road to the south-east, entered through an iron gate or stile. The church stands towards the western end of the graveyard, its exterior largely obscured by ivy, though the west gable remains partly visible. The east gable of the nave rises to around six metres and retains a steep pitch; the east gable of the chancel is gone entirely, though the return of its wall survives at the south-east angle. A narrow single-light window remains in the west gable, and the embrasures of windows in both the north and south walls of the nave are still traceable, even where the openings themselves have been broken out or breached.