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#40 Zinc Two-Piece Expansion Joint

Two-piece expansion control joint

#40 Expansion Joint is a two-piece, slip joint that finishes butt ends of adjacent panels in tall or wide walls and ceilings to allow for multi-directional movement with increased corrosion resistance.

Panels are attached to parallel studs through the expansion joint flanges, enabling the finished surface to contract or expand naturally without cracking. #40 is ideal for joining dissimilar wall types such as CMU to wood framing and at construction joints.  If installed horizontally, assure the female portion is on top.

The adjustable expansion opening, or reveal, is 1/4" to 5/8".  Additional weather shields should be installed behind the joint to enhance the weather resistance of this system.  Backer-rod and elastic sealant is often installed to assure water resistance.

The #40 Expansion Joint is also available in zinc for increased corrosion resistance.


Code Approvals & Performance Standards

  • ASTM B69 Standard Specification for Rolled Zinc
  • ASTM C1063 Standard Specification for Installation of Lathing and Furring to Receive Interior and Exterior Portland Cement-Based Plaster
  • ASTM C1861 Standard Specification for Lathing and Furring Accessories, and Fasteners, for Interior and Exterior Portland Cement-Based Plaster
  • SDS Zinc Strip Cold Formed Finished Products


Suggestions for installation precautions when installing two-piece expansion joints and double casing beads used as double expansion joints: ASTM C1063 requires that double casing beads used as a movement joint “with a flexible barrier membrane behind the casing beads.” It is ClarkDietrich’s opinion that all two-piece joints whether made from double casing beads or as a manufactured two-piece joint should be installed with the flexible peel and stick membrane behind the joint and it is further recommended that they be filled with backer rod and a highly elastic top quality sealant.

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Product Code Description
EZ40 #40 Zinc Two-Piece Expansion Joint

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