Capel Mair was built in 1825 to house a community founded in 1790; it was later rebuilt in 1845(7), 1861 and 1911, the latter to the design of J.L.I. Lewis. The vestry dates from 1951. It is in a simple round headed style, constructed of rubble stone with red brick dressings below a pitched slate roof with bracketed eaves. The chapel is entered via paired outer doors with arched heads and stone voussoirs in the lateral facade. These flank a large central arched window with recessed red brick head. Above either door is a small paned sash window with red brick cambered head. In the centre of the front elevation is a slate datestone. The right elevation is of stone, while the left elevation is roughcast; each side has a gallery window with stone voussoirs.
Inside the chapel there is a three-sided gallery with raked pews, panelled front and plain cornice. Below are four blocks of pews, with the outer blocks raked at right angles. The set fawr is curved with framed boarded panels, while the pulpit has stairs to either side with turned balusters, and a blaustrade platform either side of a three-sided pulpit. The ceiling is plastered with plaster beams.

Source: Cadw Listed Building Record
RCAHMW Inventory Documents

K Steele, RCAHMW, 20 March 2009