Up to the twentieth century, damp-proof courses in walls were not common. The inevitability of some moisture rising in walling on damp soils was accepted. Infrequently a few courses of dense bricks might be used at the base of walls as a solid bearing for walls and to act as a dpc to an extent. With the extensive building, both commercial and domestic, that occurred after the Industrial Revolution it became more common to use one of the rigid systems of dpc in the form of bricks in lowland areas and slates where the natural material was quarried and was comparatively cheap. With the introduction of bitumen felts, and later the synthetic sheet materials, bricks and slates were largely abandoned as dpcs.