The mill at Coedtrewernau (nprn 410437) is a two storey building of local rubble stone and stands under a pitched slated roof on low-lying ground some 5m north of the Clywedog Brook, in range with a house (nprn 81118). The waterwheel was on the west gable and unlikely to have been more than 3m in diameter due to the water level of the brook; it was supplied through a leat some 730m long, taking water direct from the brook upstream - no weir is shown on the first edition OS 25in map of 1889 when the mill was still working. There is evidence of a pond immediately north of the mill. The wheelpit has been filled in; excavation would probably indicate the diameter of the original wheel. The mill retains little of its machinery, only the pit wheel, wallower and spur wheel remain, all of timber construction; the surviving part of the hurst frame suggests that there were two pairs of stones. There is reference to a mill on this site in 1623; it is suggested that the present building dates from the mid-nineteenth century (Cadw Listed building description) but the remaining machinery has been dated to around 1730 so the nineteenth century date seems unlikely. A reference has been found to the existence of a 'corn mill and fulling mill' in 1770, but whether these were the same building is unknown. The corn mill ceased working between 1895 and 1903 and the waterwheel was removed around 1940. The building is currently (20 March 2010) undergoing restoration.
B.A.Malaws, RCAHMW, 22 March 2010.