at what height are guardrails required

OSHA standards require the top edge of guardrail systems to be 42 inches, plus or minus 3 inches, above the walking or working surface. The guardrail system must also be capable of withstanding a 200-pound force applied to the top rail. When this force is applied, the top rail cannot deflect to a height less than 39 inches above the walking or working surface. [1]

Midrails must be installed between the top edge of the guardrail system and the walking/working surface and must be able to withstand a 150-pound force in a downward or outward direction. [1]

In South Carolina, deviations from the standard are considered de minimis violations if the existing guardrailing consists of a top rail, intermediate rail, and posts, with a minimum vertical height of 36 to 44 inches from the top rail to the floor, platform, runway, or ramp level. [3]

Guardrails are required on work surfaces where workers are at risk of falls greater than 6 feet. [2]