Pwll-y-wrach, Colwinston is a late 18th century house, altered and extended in the 19th century and in the 1990's. It is two storeys and attic, to a plan of two parallel ranges with a rear wing. It has a nine bay front with a central entry. The main south elevation has nine windows, 3 : 3 : 3, with the central section pedimented and with the windows set more widely apart, all 6 over 6 pane sashes with rusticated surrounds and voussoir heads. The central porch is Forest of Dean sandstone ashlar with a bell-cast slate roof with dentil cornice and iron cresting. It is noted as retaining a Chinese Chippendale staircase.

Reference: Cadw listed buildings database.
RCAHMW, 2010.