Sometimes called “Rubble Masonry,” non-ashlar consists of laying material that is not uniform — in most cases, different sizes and shapes of stone set in mortar. Many historic foundations are built using this technique. However, the homes on Capitol Hill built in the late 19th century and on were primarily brick.
Historic rubble foundations were convenient because the stone did not need to be refined or “faced” to create smooth flat surfaces. A soft mortar was used for construction. Its purpose was, in some cases, more to provide an even bedding place that would fill all voids between the different sizes and shapes of stone and prevent shifting.
Today, most buildings with old non-ashlar foundations can be refurbished by tuckpointing the affected areas, as no stones have shifted a great deal.
Many historic buildings were also built with above-grade walls made from non-ashlar masonry.
A local Capitol Hill friend and neighbor sent picture of their barn in Pennsylvania. This is barn is a beautiful example of rubble masonry that has stood the test of time.