Ballytrim House, 10 Ballytrim Road, Ballytrim, Killyleagh, Co Down, BT30 9TH

Ballytrim House is a large two-storey gentleman's residence of around 1815 with a hipped roof, set within extensive grounds to the south of Ballytrim Road, approximately 1.5 miles west of Killyleagh. The building was renovated and refitted internally during the 1920s. An extensive complex of outbuildings is attached to the rear.

The front façade faces west and is symmetrical. At the centre of the ground floor is an impressive doorway with a broad panelled door flanked by Ionic columns supporting an Adam-like entablature with an oversailing cornice. Above this is a large semicircular fanlight with elaborate fan tracery. This doorway originally belonged to a Georgian residence in Dublin and was installed at Ballytrim in the 1920s; its proportions are somewhat larger than the façade would suggest. Stone steps lead to the doorway. To the left and right of it is a single sash window with Georgian panes (6/6). The first floor has three similar windows. The front façade is largely covered in ivy growth.

The north façade is considerably longer than the front and sits on a slight slope descending east to west. The ground floor has five unevenly spaced sash windows, similar to those on the front but of slightly varying size. Between the second and third windows is a side doorway with a modern glazed door. The first floor has five windows matching the ground floor arrangement. To the extreme left is a section of high walling linking to the east wing of the U-shaped outbuilding complex. This wall contains a large elliptical-headed vehicle entrance leading into a courtyard.

The south elevation is complex, divided into three sections. To the left it is hipped roofed; to the centre, flat roofed; and to the right, hipped roofed but set further back. A recently constructed hipped-roof PVC conservatory occupies the far left of the ground floor, with two windows above on the first floor. The central flat-roofed section was raised in height during the 1920s and has two windows to the ground floor and two to the first floor of varying size. The window frames are generally of Georgian inspiration and in keeping with the rest of the house, though none appear to be sash. The short east face of this section has a narrow six-pane window to both floors. The recessed section to the right has a sash window to the ground floor and two to the first floor, all matching the front design. This section abuts the long west wing of the U-shaped outbuilding complex to the east of the main house, which has been integrated with the main building, possibly during the 1920s.

The west façade of this integrated wing has three levels, though its overall height matches the rest of the building. To the left on the ground floor is a partly glazed door. To the right is a squat double sash window (6/3, 6/3). Directly above is a similar window, and on the uppermost floor is a single sash window (6/6). To the right, the ground level rises and the wing becomes two storeys. At the upper floor at this end are three sash windows (6/6, 9/9, 9/9). The lower half of the façade at this end is covered in ivy growth, and a small timber garden house has been placed against it.

The outbuilding complex is entered from the north through the large elliptical-headed archway, which leads into a small courtyard. The east façade of the west wing has four doorways and a small six-pane window. The door to the far right, partly glazed, leads into the main house. The first floor has three unevenly spaced sash windows with vertical astragals (2/2). The north façade of the southern block (the base of the U) has three stable doors to the ground floor, a small nine-pane window to the left on the first floor, and a timber-sheeted loft door to the right. The west façade of the east wing has three large vehicle openings of various sizes to the ground floor along with a pedestrian door. The first floor has four windows with modern frames (not out of keeping with the rest of the building) and a loft doorway. To the south of the outbuilding complex is a large walled garden. A long single-storey gabled greenhouse abuts the south face of the south wing of the outbuildings, and another lean-to greenhouse extends from this façade against the garden wall.

The façade of the house and much of the outbuildings is covered in roughcast, with large sections now smothered in ivy growth. All roof sections except the flat area to the south are covered in natural slate. The front portion of the roof has an overhang. There are six chimney stacks, mostly in sand-coloured brick with tall octagonal clay pots; some of these may have been rebuilt in the 1920s–30s. Cast iron rainwater goods are present throughout.

A short distance to the north and to the east of the main drive is a collection of mid-19th-century farm buildings known as The Stump. To the north side of this grouping is a two-storey rubble-built block with a gabled roof, recently converted to a showroom for locally produced furniture and offices, now with mainly modern window frames. To the south is a three-storey battlemented clock tower with a doorway to the south face and various pointed-arch slit window openings, some of which appear to be modern insertions. A wall spans between the tower and the showroom/office block.

The entrance to the main drive on the south side of Ballytrim Road features a curving gate screen with octagonal piers bearing decorative mushroom-like finials and late 19th-century-looking decorative railings and gates.