Ariss was born in Cople Parish, Westmoreland County, about 1729, the youngest of five children of John Ariss and Frances Spencer Ariss. His mother was the granddaughter of Nicholas Spencer, a member of the governor’s Council in the 1680s and a sizable landowner in the parish. Within the space of two months in the winter of 1730, one sibling whose sex is unknown died and the already-widowed father drowned. John Footman became the guardian of the two boys and two girls who had been orphaned and of their considerable estate, valued at more than £350. At Footman’s death in 1739, Wharton Ransdall assumed the guardianship of the three younger children. In November 1743 Ariss chose his older brother Spencer Ariss as his guardian. He was probably apprenticed to a local carpenter from whom he could learn the intricacies of the building process and gain practical experience in the use of tools and techniques practiced by builders.