Isolation joints are common at columns where the joint forms either a circle or diamond around the column isolating it from the slabs around it, thus accommodating any movement.  Isolation joints are also used on concrete slabs at walls that need separation from the wall slabs, the isolation joint is placed around the edge of the slab where it meets the wall.  Other areas that may require isolation joints include areas where materials change, such as from concrete to steel, or where temperature conditions change, such as a heated office which adjoins an unheated warehouse.  Additionally, isolation joints are sometimes utilised in bridges and road where differential settlement (one slab settles or moves differently than the one next to it).