4 Glen Road, Ballynalargy, Lisburn, Co. Antrim, BT27 5JR

4 Glen Road, Ballynalargy, is a one and a half storey roughcast house of early 19th century origin, possibly earlier. It faces south-east, positioned gable end to a secondary road running west of north from the Lisburn Road between Moira and Lisburn, approximately one third of a mile distant.

The house is of significant proportions with layout and detailing essentially unchanged. The exterior features plain dressings to window openings and the projecting flat-roofed porch. Wall plinths and roof corbel courses are plain, with alternating quoins at the front and rear extremities. The roof is thatched between cement skews. Each gable rises to a corbelled chimney stack, with a further stack left of centre serving the main hearth; none are provided with pots.

The front elevation is symmetrically arranged with the porch flanked to the left (south-west) by one vertically-sliding sashed window and to the right (north-east) by three such windows, all with sashes divided into two horizontally. The entrance door is of eight panels in a 4x2 arrangement. At the left end is a half door of the sheeted variety with a glazed panel in the upper part, serving the wash house. Three small vertically-sliding plain sashed windows light the upper storey. All windows have moulded sash stops, exposed frames, and traditional depth sills. A six-pane casement (3/2) occurs in the right-hand gable. At the left the building extends in red brick construction, with the main house gable above remaining plain.

The rear elevation displays three plain sashed windows at low level and a smaller plain sashed window above, along with two modern insertions. Reading left (north-east) to right: one sashed window, a modern casement, a casement of increased width, and two sashed windows, with the upper light positioned between the latter two. All openings have plain dressings; sashed windows have curved or moulded stops. Frame exposure is less pronounced than at the front, and the larger modern window has a narrow sill.

The building appears on the Ordnance Survey map of 1832/33 in smaller form. It is shown in its present configuration on the revised map of 1857 and recorded in the second valuation of circa 1860, when it was divided into two properties. John McConn occupied the larger north-west dwelling, leasing from the Hertford Estate at a rateable value of £1–15–0, while the smaller south property was sublet to John McAneany [or McAreavy] at 15 shillings. The relatively low rateable values suggest the structure may have been raised to its present two-storey form sometime after 1860.

The condition is good. The layout and interior detailing remain largely intact, though the stair has been repositioned with negligible effect on the building's importance, and modern fireplaces have been added—alterations encountered frequently in such buildings. Sanitary facilities could readily be incorporated by adapting the existing wash house within the main walls. The building demonstrates vernacular character and retains significant architectural and historical interest through its proportions, structural system, quality of interior survival, and local importance as a rarity of its type.