Thin brick is unlike regular facing brick when it comes to expansion joints. Because of the thickness of the material, the substrate plays a bigger role in the movement of the wall. As most substrates and adhesion materials are concrete products, the primary movement of the substrate is shrinkage. Crack control is placed at the spacings and detail as required for stucco.
A control joint in stucco is intended to relieve stress and limit or control the cracking in the membrane of the stucco only. Usually installed at a maximum of 144 square feet. It is not necessary and in fact can be detrimental to cut the lath behind the control joints. A control joint will not stop stucco from cracking if the stresses imposed upon the stucco membrane are greater than can be dissipated by the stucco and/or the control joint.
ASTM C1063 requires that panel areas are no larger than 144 square feet. In addition, the maximum spacing of control joints should be less than 18 ft. The aspect ratio of the panel should also be held to a maximum length to width ratio of 2 1/2 to 1.
An expansion joint in stucco is a two-piece slip joint that is installed at a similar expansion joint in the structure of building. When installing an expansion joint, the framing, sheathing and lath should be cut to create a true plane of expansion. Consult a stucco representative for proper placing of control joints.