Low-slope or steep (1926.500)
29 CFR 1926.500(b) defines a low-slope roof as having a slope less than or equal to 4 in 12 (vertical to horizontal). A steep roof is greater than 4 in 12.
Exactly 4:12 is low-slope. Calling it steep is the named common error. There is no flat-roof exemption from Subpart M, and the 50-ft width figure (below) never changes the slope classification.
The trigger height: 6 feet
Under 29 CFR 1926.501, fall protection is required at 6 feet (1.8 m) above lower levels for low-slope roofing work, steep roofs and residential construction.
Traps:
- 4 feet confuses the 4:12 slope boundary with a height.
- 10 feet is the warning-line distance from edges perpendicular to mechanical equipment travel.
- 15 feet is not the Subpart M roofing trigger.
Low-slope methods (1926.501(b)(10))
For roofing work on a low-slope roof with unprotected sides 6 ft or more above a lower level, the listed methods are:
- guardrail systems, safety nets, or personal fall arrest systems;
- a warning line combined with a guardrail, net, personal fall arrest or safety monitoring system;
- a safety monitoring system alone, but only on roofs 50 feet (15.25 m) or less in width.
On a 60-foot-wide roof, a safety monitor alone is not allowed; that is the named common error. The warning line plus safety monitor combination is still fine at 60 ft.
Steep-roof methods (1926.501(b)(11))
For steep roofs, 1926.501(b)(11) lists only:
- guardrail systems with toeboards,
- safety nets, or
- personal fall arrest systems.
Warning lines and safety monitors are low-slope methods and are not listed for steep roofs; allowing warning lines on a steep roof is a named common error. A guardrail without toeboards does not meet the steep-roof rule. A warning line paired with personal fall arrest is a low-slope combination, not the steep-roof list.