Islandreagh Dyeing and Finishing Company, 30 Islandreagh Drive, Muckamore, Co Antrim, BT41 2HB

Islandreagh Dyeing and Finishing Company is a former beetling mill complex and dye works built around 1810, located south of Islandreagh Drive near Muckamore. The complex is roughly L-shaped, with its principal buildings arranged around a central entry space that opens into a turbine house. The site sits at the base of a sloping landscape, sheltered by mature trees, with the river immediately to the west and surrounded by pasture.

The main beetling shed (Beetling shed 1) is a two-storey multi-bay structure with an attic, built of random rubble stone in lime mortar, aligned east-west. It has a pitched natural slate roof with brick eaves and half-round cast-iron rainwater goods. The principal north elevation contains ten openings at each floor, with timber 2/2 sashes set in brick dressings and concrete sills; some have been replaced with 1/1 sashes and some partially infilled with ventilation louvers. A t&g sheeted door with two-light transom sits at the extreme right. The left end is built into a bank and accessed by ascending concrete steps. The left gable is single-storey, abutted by a modern concrete lean-to shed. A red brick platband marks the attic level, which is lit by two windows. The south elevation mirrors the north, with eight openings at each floor including a panelled timber door, partly sheeted over. The right gable features multiple ground-floor openings with rubble stone voussoirs: a cement-reveal window, a rubble stone infilled door opening with an axe housing mortice, a segmental-headed infilled opening with a six-pane fixed window and brick apron, and a segmental-headed t&g sheeted loading door set above ground level. Above this door is a grooved wheel on an axle spanning the entry, fixed to a corresponding wheel on the dye house opposite. The first floor has a window to each side and a loading door infilled with fixed four-light windows and a timber sheeted panel, with a double-header relieving arch above. A steel I-beam with chains and a timber beam with pulley attachments are also affixed to the gable. A mill stream flows beneath the beetling shed by means of a two-span brick inlet with elliptical-headed arches.

Beetling shed 3 is a single-storey multi-bay structure with M-profile artificially slated double hipped roofs, except the right bay which is gabled with perpendicular ridge; ridge and hip tiles are roll-topped. Wall construction and windows match the main block, though some casements have been replaced. The east elevation is fifteen openings wide to the hipped section. Four brick piers projecting from the wall-head support a lean-to corrugated metal canopy with steel supports at the lower end, covering an elliptical-headed vehicular entrance door with a smaller window to its left; most other windows are infilled with brick. The extreme left contains a single-bay gabled engine room with a double-height opening of a double-leaf t&g sheeted door surmounted by a round-headed six-light fixed window, all in brick reveals. The north elevation is symmetrical, three openings wide with central casements to each section; the remainder is infilled with brick. The west elevation is similar to the east, with many windows infilled or replaced with casements. The south elevation is abutted by the roofless dye houses.

The dye houses are adjoining double-height roofless blocks whose curved south elevation suggests a former Belfast truss roof structure. They are detailed as the main block with vestiges of lime render to the west elevation. Multi-pane timber windows include nine-pane examples with three-light top-opening casements to the east elevation, and twelve-pane and six-pane windows to the west. Dye house 2 bridges a mill race passing underneath at a skew. The south elevation is abutted by corrugated metal structures including a canopied lean-to dye house extension and a pitched roof structure raised on steel supports over a partially open enclosure bounded by a low concrete wall.

Beetling shed 2 (the turbine house) is a double-height single-bay rectangular structure with a corrugated metal roof over Belfast truss framing and plastic rainwater goods. Walling is rubble stone laid to courses. Windows are nine-pane without sills, with heads at eaves level; the east elevation has six openings, with various ground-floor openings including a door with rubble stone voussoirs and a metal roller door. The south elevation has a segmental-headed door opening with a brick head. The west elevation is abutted by corrugated metal sheds. Entry is at the north, with corrugated metal walls and a pair of steel doors. A sluice set parallel to the turbine house at the east has remains of a sluice gate at its north end.

The boiler house is a double-height rectangular block located immediately to the rear (west) of Beetling shed 3, connected by a system of pipes. A square-section chimney approximately 100 feet high rises from the west end, featuring a corbelled cap with metal straps fixed to the shaft at regular intervals. The boiler house has two vehicular entrance openings at the east gable: the left has a segmental relieving arch over a timber lintel and timber sheeted doors; the right has corrugated metal sliding doors. A glazed roundel is set at the apex. The remaining elevations are blank.

The mill offices are a detached single-storey three-bay building located to the north-east of the complex. Rectangular on plan with a central lean-to projecting porch, it has a pitched natural slate roof with angled ridge tiles and cast-iron rainwater goods. Walls are random rubble stone with brick quoins. Windows are timber 2/2 sliding sashes with concrete sills and brick dressings. The principal elevation has a central porch detailed with quoins and a corrugated metal roof, containing a four-panel timber door with sidelights and transom, accessed by two stone steps. Two windows flank the porch on either side. The gables are blank.

The mill complex is accessed from Islandreagh Drive via a tree-lined avenue that leads to Islandreagh House and crosses the railway line by means of a rubble stone bridge.