St Andrew's church stands above Pentwyn, on the west side of the minor road from Pengarnddu to Deri and Bargoed, in a rectangular churchyard used as a cemetery.
The building was opened as a school in 1856 and extended with a chancel to form a mission chapel in 1863. The chancel attached to the schoolroom (then in the parish of Gelligaer) was opened for public worship in November 1864. An adjacent burial ground was consecrated in 1866. The chancel, which was occupied by the choir, was separated from the schoolroom (to be closed during weekdays) by low doors and a curtain.
It was remodelled in 1930, when it was reduced in size - the schoolroom demolished - and restored in 1980. The present building is of rubble stone with brick dressings under a steep pantile roof. The entrance front faces east and has double boarded doors offset to the left and two fixed-pane windows centre and right, all under segmental heads. The windows are the original openings of 1856, while the doorway is a twentieth century remodelling of the original pointed doorway. The north gable end belongs to the 1930 remodelling and has three stepped narrow lights. The south gable end is pebble-dashed, whilst the rear (west) wall is of rubble.
Recorded as part of RCAHMW Uplands Initiative Project, W B Horton, H & H, 11/09/2013.
Additional source: http://www.fochriwhistory.co.uk/page181.htm

David Leighton, RCAHMW, 17 December 2014