Churches with attached living quarters are not especially common, and the arrangement here, where ecclesiastical and domestic space share a single structure, gives the building an almost defensive, self-contained quality. The tower is entered through a semi-circular headed doorway with chamfered sandstone jambs, the upper storey is offset from the lower, and it is lit by a lunate window, a crescent-shaped opening that catches light in an unusually deliberate way. The nave itself, entered through a round-headed doorway on the south side, is lit by tall plain round-headed windows with brick facings, giving the interior a spare, unadorned character.

The building is a plain rectangular structure of the undivided nave and chancel type, meaning that, unlike many medieval churches, there is no structural division between the two liturgical spaces. Internally it measures around 21 metres in length and 5.8 metres in width. There was originally a north aisle, accessed through two arched openings in the north wall of the chancel, though these openings are now blocked. Sometime after 1609, a north wing was added to the structure, and the graveyard in which it sits carries its own separate record in the Sites and Monuments Register. The site may rest on ground previously associated with St. Comgall, an early Irish monastic figure, which would place this location within a much older pattern of Christian settlement along the northern Dublin coast, though the current fabric of the building belongs to a later period. The reference in Dillon Cosgrave's 1977 account remains one of the primary descriptions of the structure.

The church sits within a graveyard at the north-eastern corner of the Clontarf Castle Demesne, and that boundary position means it can feel slightly peripheral even to those who know the area well. The blocked arched openings in the chancel's north wall are worth seeking out if you can access the interior or examine the walls closely, as they hint at an earlier spatial arrangement that was gradually altered over time. The bellcote over the west gable is a single and relatively tall feature, making it a useful landmark when approaching from the surrounding grounds.