Differential Movement of Slab‐on‐Grade Structures

The study is intended to summarize data on the differential movement of slab‐on‐grade structures. All the structures in this study are one‐ and two‐story single‐family detached houses and condominiums. The results indicate that cracking in the gypsum wallboard panels is likely to occur if the angular distortion of the foundation exceeds 1/300. For single‐family residences on lightly reinforced slab‐on‐grade, the cracking of gypsum wallboard panels is likely to occur when the maximum slab differential exceeds 1‐1/4 in. (3.2 cm). For single‐family residences, structural damage of the wood columns and beams is likely to occur if the angular distortion of the foundation exceeds 1/100. This value exceeds 1/150, which is the angular distortion that caused structural damage to the beams and columns of structures studied by Skempton and MacDonald in 1956.