A roof perimeter warning line system is a passive restraint fall protection system. Warning lines create a visual cue and serve as a barrier to restrict workers from approaching hazards. Frequently there is confusion about roof warning line systems, including rooftop warning line spacing in fall protection.
OSHA requires that work at less than six feet from a roof edge requires conventional protection such as a guardrail, safety net or personal fall arrest systems. In the Walking-Working Surfaces standard, OSHA defines a designated area as “A distinct portion of a walking-working surface delineated by a warning line in which employees may perform work without additional fall protection.” According to OSHA’s 29 CFR 1910.28(b)(13)(ii), for work on low-slope roofs, when the work done is between 6 feet and 15 feet from the roof edge and when work is both infrequent and temporary, a designated area can be used. A designated area can also be used when workers are working greater than 15 feet from the edge of a low- slope roof. When positioning a warning line, maintain the required distance, depending on whether the work is temporary or infrequent.
For roof warning line systems to be within OSHA compliance, the following must be satisfied:
- The warning line is used 15 feet or more from the roof edge.
- The warning line meets or exceeds OSHA’s setup requirements.
- No work or work-related activity takes place between the warning line and the edge (or hole).
- A rule is implemented which prohibits employees from going past the warning line.
OSHA’s warning line set up requirements (OSHA’s 29 CFR 1926.502(f)) include:
- All warning lines must be flagged with a highly visible material and spacing must not exceed 6 feet intervals.
- Warning lines are to be supported so the lowest point of the sag is no less than 34 inches and no more than 39 inches from the walking/working surface.
- After being rigged with warning lines, stanchions shall be capable of resisting at least 16 pounds of force.
- The warning line must have a minimum tensile strength of 500 pounds.
Additional Source: https://www.osha.gov/laws-regs/standardinterpretations/2005-01-03