Issued – November 2019
Control and/or expansion joints are the Stucco industry’s solution for minimizing and controlling cracking in stucco wall systems. There is controversy and confusion in our industry about their use and installation – particularly as to whether the lath should be continuous or discontinuous (cut) at the control joint. However this issue is fully addressed in the International Building Code (IBC) and in ASTM C 1063.
Structa Wire Corp. per ASTM C 1063 – recommends that Control Joints be used to delineate stucco areas not greater than 144 sq. ft., or at maximum distance of 18 feet between Control Joints. Further – Structa Wire advises that the installation of control joints should fully comply with recommendations set forth in ASTM C 1063.
ASTM C 1063 – 19 states in section 188.8.131.52: “Lath shall not be continuous through control joints, but shall be stopped and tied at each side”
In summary – Structa Wire Corp. recommends the cutting and fastening of the lath at locations where vertical control joints are to be installed and wire tying the control joints flanges to both sections of the lath. In this way control joints can accommodate movement while providing a stress relief location within the stucco wall to ensure minimal stucco cracking.