Rathlin Island, 1B Knockans, Ballycastle, Co Antrim BT54 6RT

1B Knockans is a modest detached single-storey, two-bay prefabricated timber-framed house built around 1904 to designs by Speirs & Co., a Glasgow-based firm of designers and erectors of iron and wood buildings. It stands on the south side of the road running east-west along the southern edge of Rathlin Island, County Antrim, approximately 2 kilometres west of the Ferry Port.

The house is irregular on plan, consisting of a two-bay main block with a projecting L-plan porch to the south, and a rubblestone outbuilding to the southwest. The roof is pitched and clad in corrugated iron, with painted A-frame timber bargeboards to the north gable end. There is a single pebble-dash chimneystack with a tar-covered base at the centre of the roof apex. Rainwater goods are a mixture of original cast iron and replacement uPVC, on plain eaves. All external walls are clad in corrugated iron throughout.

Window openings are square-headed throughout and fitted with painted timber casement windows. The principal (east) elevation is asymmetrical, with two openings each containing paired painted timber casement windows with timber surrounds and single glazing. A mono-pitched felt-roofed L-plan porch projects to the south, fitted with replacement uPVC rainwater goods. The north-facing door opening of this porch contains a timber door frame and a timber-sheeted door, above which is fixed the maker's sign reading "SPEIRS & COY, DESIGNERS AND ERECTORS OF IRON & WOOD BUILDINGS, GLASGOW". The south elevation comprises the main gable end and the south elevation of the lean-to porch. The rear (west) elevation has three window openings: two with paired painted timber casement windows and one single window to the lean-to section, all with timber surrounds and in varying degrees of disrepair, some retaining their original single glazing. The north elevation is a gable end with corrugated iron cladding and A-frame timber barge and tie boards. Steel stabilising pegs and cables are embedded in the ground at the outer ends of the building and span over the roof as protection against wind.

Immediately to the southwest of the house, and within its curtilage, is a rubblestone and brick outbuilding with mono-pitched corrugated fibreglass roofs, contiguous with a bonded rubblestone boundary wall. This outbuilding has a single square-headed window opening with a fixed timber window and a single square-headed door opening with a timber-sheeted door to the east elevation. The rubblestone boundary wall to the south of the house includes a timber pedestrian gateway with a steep gorge beyond. The house is set back from the road behind a garden with a gravel path to the entrance, and is bounded by a drystone wall to the southeast, west, and north. The wall to the southwest is of bonded rubblestone with a rough concrete capping. A replacement wrought-iron pedestrian gate provides access from the main road. Maps indicate that a well is located immediately west of the house.

The building retains much of its original fabric, including the corrugated iron cladding, timber casement windows, the maker's plaque, and some of the original cast-iron rainwater goods.

The house first appears in the valuation books in 1905, indicating construction the previous year, and a building of similar plan is shown on this site on the 1904 Ordnance Survey map. It was erected by the Rathlin Limestone Company, a Scottish concern apparently established in or just before 1901, recorded in the Post-Office Annual Glasgow Directory from 1900–01 until 1911–12 as having offices at 53 Waterloo Street, Glasgow. Limestone had long been excavated on Rathlin Island, as the number of quarries marked on the 1832 Ordnance Survey map attests. By the early 1900s, commercial quarrying was underway, supplying stone to steel smelters in Scotland. A stone pier was constructed at Killeany, just south of this site, served by a short stretch of narrow-gauge railway, with the Rathlin Limestone Company apparently at the centre of this venture.

The first recorded occupant was David Galloway, a Scot who served as quarry master for the company on Rathlin until 1907. He was succeeded by John McPhee, a native of Skye, who in the 1911 census is recorded as occupying the house with his wife Mary, their four children, and a young nephew, Hector McDonald. The building is noted in the census as a second-class house with two rooms in use. According to valuation records, John McPhee was still living there in 1929, and the property remained in the ownership of the Rathlin Limestone Company until at least that date. The firm appears to have left no record beyond around 1911, and it is probable that quarrying operations had declined or ceased by 1929. At some point thereafter the house appears to have become a private residence with no connection to the quarrying industry.

Speirs & Co. was founded by brothers John and James Speirs in the 1880s and by the early 1900s specialised in the design of partly prefabricated timber-framed buildings, some clad in corrugated iron, most notably churches, halls, schools, clubhouses, hospital structures, and bungalows. The firm is most notably associated with the provision of prefabricated timber-framed and corrugated iron-clad structures for the Episcopal Church throughout Scotland. This house may be one of the very few — and quite possibly the only — example of their work in Northern Ireland.

As a type, timber-framed and corrugated iron domestic architecture was established in Britain in the 1840s and grew more popular in the latter half of the 19th century with increasing industrialisation. 1B Knockans is a fine and rare surviving example of this tradition, and is also significant as evidence of the improved transport links and importation of materials between Scotland and Ireland in the late 19th and early 20th centuries. The relatively intact setting, including the earlier rubblestone boundary features, adds further to its interest. Much of the significance of the building derives from its construction, materiality, and historic associations.