Excavations carried out in 1967 uncovered evidence that the stone structure was built directly over the remains of an earlier timber church, one that may date to as far back as the 8th century.

The discovery matters because it illustrates something easily overlooked in Irish ecclesiastical archaeology: the stone churches we associate with early Christian Ireland were not always original foundations. Timber construction came first. These wooden oratories and churches, modest and perishable, were the earliest built expressions of the new faith in the Irish landscape, and they survive almost nowhere above ground. Finding their traces beneath later stonework, as happened at Ardagh, is one of the few ways we know they existed at all. Ardagh itself has considerable early Christian significance; it is associated with Saint Mel, a bishop said to be connected to the Patrician mission, and the broader demesne sits within a landscape that was clearly an important ecclesiastical centre. The 1967 excavation placed the timber phase tentatively in the 8th century, which would situate it in the period when Irish monasticism was at its most expansive and influential, producing manuscript art, scholarship, and a network of foundations that stretched across Britain and continental Europe.