1. St Dyfrig's Catholic church is built in the Byzantine style of brick with a high nave and choir balcony. The church opened in 1927. Reordering carried out in the early 1950s including a new free-standing altar. In 1999 a life-size crucifix and side panels by Penanne Crabbe were installed. There is a 'Lourdes Grotto' situated on the east boundary. 

2. A mission was established at Treforest from Newbridge in 1853. Four years later a stone-built Gothic chapel-school was opened in Wood Road (Old Park Terrace), dedicated to St Dubritius (Dubricius, Dubric or Dyfrig (Welsh)), who evangelised much of southeast Wales during the sixth century. The chapel remained in use until the present church was completed in 1927. The chapel was later known as the Institute. The 1857 school-chapel in Old Park Terrace still survives but is currently unused and boarded-up. In 1921 a site on Broadway on the east side of Treforest, close to the River Taff, was leased for the building of a new church, parish hall and presbytery (the freehold was later acquired).

With rapid industrialisation of the area during the C19th and early C20th, a large number of Catholic workers and their families moved to the South Wales Valleys. This meant that a larger church would be needed to cope with the increased congregation. The presbytery and memorial hall (dedicated to the men of the parish killed in the First World War) were built slightly earlier than the church in 1923. Archbishop Mostyn laid the foundation stone for the new church on 4th November 1926 and the building was completed within twelve months, with the formal dedication and opening by the archbishop on 14th November 1927, the feast of St Dupritius. The architect was Arthur George Lynham FRIBA of Thomas & Morgan & Partners, Pontypridd and the church was built for a cost of approximately £20,000. The foundation stone can be seen in the external wall of the narthex in the west elevation. The church is designed in a free-basilican style, combining Romanesque and Italo-Byzantine elements. The walls are constructed of brick with stone dressings and coped gables. The roof is pitched and covered in natural slate with painted metal rainwater goods.

The church underwent unspecified alterations in the 1950s, and possibly included the addition of the Lady Chapel in the south elevation. Post-Vatican II reordering saw the removal of the original altar, altar rails, font, and the installation of a forward altar. The new altar and the church were consecrated by Archbishop Murphy of Cardiff on 6th November 1975. In 1999 furnishings by the local artist and parishioner, Penanne Crabbe (d.2008) were added including the Stations of the Cross and the corpus of a crucifix carved from pews in the church. St Dyfrig’s Church was designated as a Grade II listed building by Cadw on 26th February 2001. It was listed for its architectural interest as a distinctive and well-preserved church using the early Christian Byzantine style. The Presbytery and adjoining Community Hall were also designated as Grade II listed buildings on 26th February 2001 where the buildings provide an important group value for the church at St Dyfrig’s.

RCAHMW, 2016. Updated by M. Powel, RCAHMW. October 2023.

References: http://www.pontypriddrcdeanery.org.uk/churches/treforest/Registers-and-Archives.html; St Dyfrig's Roman Catholic Church. Building Resilience:Safeguarding our Ecclesiastical Heritage. RIBA Stage 2 Report, DittrichHudsonVasettiArchitects, June 2023; Cadw Listing Summary ref: 24878