The initial development in the 1840s took the form of a ribbon settlement that spread southwards from Aberdare along Cardiff Road. During the 1850s the settlement began to spread outwards from Cardiff Road as Curre Street, Holford Street, Gwawr Street and Lewis Street, amongst others were constructed. Settlements also tended to grow in the vicinity of the collieries: Incline Row and Bell Place around Aberaman Colliery; Blaengwawr Row and Blaengwawr Cottages to the North at Blaengwawr Colliery. Two contemporary accounts give a vivid description of the conditions prevailing in Aberdare as the area struggled to cope with the population explosion.
The Vicar of Aberdare, Reverend John Griffith, writing to the inspectors compiling the Report on the State of Education in Wales in 1847, states that although the settlement had only been in existence 18 months its population was already 1,200. The population was expected to rise to 4,800 within a year. Eighty masons and fifty carpenters were working at that time to provide housing.
Thomas Rammell in his 1853 Report to the General Board of Health, describes the poor condition of the dwellings built in these years. He singles out Aberaman Road and Treaman in particular as being built in unsuitable locations with poor drainage leaving them liable to flooding and damp. In turn the inhabitants were more susceptible to disease. Aberaman also suffered because it did not have a local water source so its inhabitants had to travel at least a quarter of a mile to the nearest water source at Blaengwawr. Consequently:
"There is much waiting at the spouts; three hours for a turn is no uncommon time. People have been known to go for water immediately after their dinner at twelve o'clock and return at six o'clock without any, their turn not having come round. They get up at two or three o'clock in the morning to go for water. A hundred jugs in a row are at times seen at the spouts. There is much immorality at the spouts, from people waiting there and having nothing to do."