Abstract: The building system employs precast corners (16) and elongated walls (12) with integral footings (14 and 18) to construct a foundation and basement. Precast first elongated wall sections (50) and corner sections (52) and floor slabs form a first level. Upper level wall sections (74), corner sections (76) and floor slabs (72) form an upper level. Gable sections (90), a ridge beam (92) and roof slabs (94) form a roof. The precast members all include a steel mesh reinforcement (102, 104 and 106). Sections are rigidly connected together at their ends (58 and 68) by connector assemblies (108 and 160) that are connected directly to the reinforcement (102). The sections are secured together by sheebolts (120) that extend vertically from a lower section into an upper section.