Isolation joints permit horizontal and vertical movements between abutting faces of the slab and fixed parts of a structure.
Contraction joints provide for horizontal movement in the plane of a
slab or wall and induce controlled cracking caused by drying shrinkage.
Horizontal construction joints in walls with V-shaped (left) and beveled
(right) rustication strips.
Typical contraction joints
Construction joints are stopping places in the process of construction.
Construction-joint types a, b, and c are also used as contraction joints.