Final answer:
The controlling contractor must notify steel erectors of a safe structure, pre-existing conditions, and corrective actions before work commencement.
Step-by-step explanation:
Before authorizing work to begin, the controlling contractor must provide steel erectors with written notification regarding several critical items to ensure safety and compliance with regulations.
These items include the confirmation that the structure is safe to begin steel erection, any pre-existing conditions that could affect the steel erection processes, and acknowledgment of any corrective actions that have been taken to remedy potential hazards. All necessary precautions and checks must be documented and communicated to the steel erectors to prevent any safety incidents on the construction site.