Siloh Chapel, including Schoolroom to rear, and attached house (18 Gloddaeth Street)

Chapel in Baroque style. Red sandstone and grey limestone; slate roof. Upper floor faced with blocks of limestone with sandstone ashlar dressings; rusticated ground floor, balustraded parapet, and cupolas faced with sandstone ashlar. Each end bay of North-east elevation projects forward and is ornamented with quoins on first floor and crowned by a domed cupola. Each first floor window with shouldered architrave with keystone and broken triangular pediment, and with segmental pediment above eaves level. Flat-arched window with keystone on ground floor. Centre bay also projects; Venetian-window on first floor with rusticated Doric columns and Ionic pilasters with broken-triangular pediment over, above eaves level; wide portico on ground floor with entablature and segmental pediment with "Siloh" in tympanum of pediment and with the following inscriptions in the frieze:"19 Addoldy y Methodistaid Calfinaidd 05". Each intermediate bay with a balustraded parapet and with a narrow window on both first and ground floors, first floor windows with rusticated pilasters and entablature and with balustrading to apron. South-east elevation of six bays with projecting bay at each end and, the North-easternmost bay continuing the articulation of the corner bays of the North-east elevation. South-easternmost bay with Venetian window on first floor with rusticated pilasters and with plain window on ground floor. The four intermediate bays have semi-circular headed windows on the first floor with moulded heads and with keystones extending up to the eaves cornice; plainer openings on ground floor. North-west side elevation similar to South-east elevation. To rear, single storey schoolroom block with hipped slate roof. Also to rear, facing Gloddaeth Street, attached 2-storey, 3-window house; grey rock-faced stone, slate roof. On first floor, 3 paired Gothic windows with sash glazing. On ground floor, from L, square bay window with 2 sash windows, doorway with boarded door, splayed bay window with sash glazing, further doorway, and square bay window as at other end.

Inside the chapel there is a gallery on three sides supported by slender fluted iron columns; ceiling divided into rectangular panels with circular panels inset within them; wide arch over organ behind sedd fawr.