You are installing a guardrail system on a roof. What is the minimum height requirement for the top rail?
Correct Answer
B) 42 inches
OSHA requires guardrail systems to have a top rail height of 42 inches (plus or minus 3 inches) above the walking/working surface. This standard applies to all guardrail installations.
Why This Is the Correct Answer
OSHA Standard 29 CFR 1926.501(b)(1) specifically requires guardrail systems to have a top rail height of 42 inches (plus or minus 3 inches) above the walking/working surface. This measurement is taken from the surface where workers are standing to the top of the guardrail. The 42-inch height provides adequate protection while allowing workers to lean against or hold the rail comfortably. This standard applies universally to all guardrail installations in construction, including rooftops, scaffolds, and elevated platforms.
Why the Other Options Are Wrong
Option A: 39 inches
39 inches is below the OSHA minimum requirement and would not provide adequate fall protection for workers
Option C: 45 inches
45 inches exceeds the maximum allowable height of 45 inches (42 + 3 inches tolerance) under OSHA standards
Option D: 48 inches
48 inches significantly exceeds OSHA requirements and would be impractical for worker use and safety
Memory Technique
Think '42 = Answer to Everything' (reference to Hitchhiker's Guide to the Galaxy) - 42 inches is the answer to guardrail height questions
Reference Hint
OSHA Construction Standards 29 CFR 1926.501 - Fall Protection in Construction, specifically subsection (b)(1) for guardrail systems
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