Derg Valley Hospital, 37 Lurganboy Road, Castlederg, Strabane, Co Tyrone, BT81 7BJ

Derg Valley Hospital is a substantial detached former fever hospital, built around 1847 and associated with the now-demolished Castlederg Union Workhouse. It is a multi-bay, two-storey stone building constructed to an H-shaped plan, facing south, and sits on an elevated site with landscaped grounds and some later single-storey structures to the west. A tarmac avenue to the west is enclosed by a low rubble stone wall to Lurganboy Road. Although the Victorian interior has been removed during the 20th century and unsympathetic extensions were added during the same period, the original masonry and H-plan remain decipherable, and the building stands as an historically significant reminder of the hardships of the 19th century.

The front block is built of coursed and squared limestone with a tooled stone plinth course. The remainder of the building — including the rear spine wing and former morgue — is constructed in random rubble limestone. Window openings throughout are square-headed with voussoired stone lintels, tooled stone surrounds, stone sills, and uPVC windows fitted with security steel panels. The roofs are pitched and covered in natural slate with black clay ridge tiles, timber bargeboards, and cast-iron rainwater goods carried on iron drive-through brackets. Stone chimneystacks have been removed from the front block; the rear spine wing retains large rendered chimneystacks with shallow panels and capstones.

The front elevation is symmetrical, with a central multi-bay two-storey rendered flat-roofed extension added around 1950. The gable-ended side elevation to the front block retains a projecting chimney, though its chimneystack has been removed, and carries an iron fire escape. A two-storey rendered flat-roofed extension at the northwest corner returns to the rear elevation. The rear spine wing runs perpendicular to the front main block and shares the same roof type, window style, and rubble stone walling. Abutting the rear gable of this spine wing, and set perpendicular to it, is a single-storey former morgue. A concrete chimneystack is attached to the rear gable of the spine wing. The east gabled elevation mirrors the west, also with a fire escape and a two-storey extension.

The building was designed by George Wilkinson, who was appointed architect to the Poor Law Commissioners in 1839 and held the post until 1855. He was responsible for designing all 163 workhouses built in Ireland between 1840 and 1853. Wilkinson's standard workhouse plan comprised three main parts: a separate front building, a main building, and an infirmary building at the rear joined by a spine at right angles to form an H-plan. At Castlederg, the arrangement deviated slightly from the standard: the front building was split into two smaller units to open the view toward the main building, and the main building was of two storeys rather than the three or four used in medium and large designs. The workhouse was completed on 20th February 1841, one of nine in County Tyrone and among the first built in Ireland after those in Dublin, Cork, and Londonderry. It was built by contractor John Maguire of Omagh at a cost of £2,100 with a further £484 for fittings — the lowest construction cost of any workhouse in Ireland — and, along with Gortin, was the smallest, accommodating 200 inmates. Economy was achieved by laying floors in mortar or earth, using sleeping platforms rather than beds, whitewashing rough stone walls rather than plastering them, and omitting ceilings to the dormitories.

Wilkinson described his architectural approach in his own report, stating: "The style in which the buildings are designed admits of execution best suited to the nature of the materials with which the country generally abounds. The carboniferous or mountain limestone has an irregular fracture suited for the mode of execution generally known as rubble masonry, with which the walls are proposed to be constructed; and which, in point of strength and durability, is equally suited for the building with dressed stone or ashlar work, and would have a more characteristic appearance. The necessarily conspicuous situation, which many of the buildings must occupy, suggests the above style as the least obtrusive; while its gabled roofs and elevated chimney shafts give it a pleasing and picturesque appearance. The windows are constructed with mullions and transome heads and diamond lights." Architectural historian Hugh Dixon has noted that Wilkinson was choosing a style associated with Tudor and Jacobean almshouses in England.

The Poor Law (Ireland) Act was passed in 1838, modelled on similar legislation in England and Wales, dividing Ireland into Poor Law Unions centred on market towns, each with a workhouse for the destitute. Unlike England and Wales, no outdoor relief was provided: to receive assistance, the poor had to enter the workhouse. The system was funded by a rate on householders and tenants based on the valuation of their properties, and administered by elected Boards of Poor Law Guardians.

In 1845, as famine and associated disease took hold across the country, the Poor Law Commissioners began ordering the construction of fever hospitals within workhouse grounds, particularly in areas where no such facility existed locally. Castlederg and Clogher were the first in the northwest to provide fever hospitals, and by the time construction began at Castlederg the famine was at its height. The site was presented by Sir Robert Ferguson in August 1847, and the fever hospital was completed by November 1848, built by contractor William Mullan. Wilkinson prepared three standard designs for fever hospitals, though few were built exactly to any of them. Castlederg's fever hospital was constructed to an H-plan — two standard wards built back to back, a configuration thought to have been used where space was restricted — and was built to accommodate 36 people.

The Castlederg Union Workhouse and its associated fever hospital first appear on the second edition Ordnance Survey map of 1855 (the 'Castlederg Union Work House' and 'Fever Hospital' to the rear also appearing to be shown on the first edition of 1833). By the third edition of 1905, the buildings are captioned 'Union Workhouse' and 'Hospital (Infectious Diseases)' respectively. On the fourth edition of 1939, the workhouse has been demolished and replaced by 'Edwards PE School', while the fever hospital is now captioned 'Union Hospital' but retains its former plan. The workhouse is listed in Griffith's Valuation (1856–64) but the fever hospital does not appear there, nor in subsequent revisions. The workhouse was valued at £100, though later revised down to £60. The lessor is recorded as Sir Robert Ferguson Bt, becoming John G. Smyly in 1862.

The workhouse closed in 1929 and lay empty for a few years before being demolished to make way for Edwards School, built in 1938. In the same year the fever hospital building was modernised to form the core of what became the Derg Valley Hospital. The workhouse system was formally ended in Northern Ireland in 1948, by which time most smaller workhouses had already been converted to district hospitals under government encouragement. The Derg Valley Hospital is one of many such former workhouse and fever hospital buildings across the province still in use today as part of hospital complexes.