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.

Maximum Spacing of Contraction Joints (Feet)