Control lines for CDZs

A control line for a Controlled Decking Zone (CDZ) must be erected no less than 6 feet and no more than 90 feet from the unprotected leading edge. According to the non-mandatory guidelines in Appendix D to Subpart R, the control line should run approximately parallel to the leading edge and be connected on each side to a stable anchorage point like a guardrail system, wall, or stanchion.

Access to a Controlled Decking Zone (CDZ) must be strictly limited to only those employees engaged in leading-edge work. As described in Appendix D to Subpart R, the purpose of a CDZ is to control access to areas where metal deck is being initially secured and other operations connected with leading-edge work are taking place. An OSHA Letter of Interpretation from April 28, 2009, clarifies that trades not involved in installing metal decking, such as those installing curtain walls, are not permitted to work in a CDZ. Only employees who are properly trained in leading-edge work are authorized to enter the zone.

A control line for a Controlled Decking Zone (CDZ) is intended primarily to serve as a visual warning, not as a physical barrier to stop a fall. An OSHA Letter of Interpretation from August 10, 2010, clarifies that a control line's purpose is to restrict access by visually warning employees of an unprotected area and clearly designating the CDZ. While the line must have a minimum breaking strength of 200 pounds as outlined in Appendix D to Subpart R, it is not a substitute for a guardrail or personal fall arrest system.