Hirdrefaig was built in three phases, although only the latest section, built in c1710, is dateable. The house underwent extensive alteration in the late eighteenth century. At this period the roof was obscured when the front and side walls were heightened to form a parpet. The sash windows at the front and some of those on the northern side are original. Little remains of the earlier part of house internally except for some stop-chamfered beams and a staircase. However, there is some good early eighteenth century panelling in the later part.

(Source: site file AN/Domestic/SH47SE, from an entry by L Monroe. Also RCAHMW Inventory:Anglesey, 1937 (1960 reprint), p. 79)

J Hill, RCAHMW, 17 November 2003 .