What is the required height for guardrails when the floor is more than 600 mm above the lower floor?

When dealing with guardrails, the required height is critical for ensuring safety in construction environments. In scenarios where the floor level is more than 600 mm above a lower floor, the standard height for guardrails is set at a minimum of 1,070 mm (or 42 inches). However, in certain applications, a height of 900 mm (or 36 inches) may be specified for general construction purposes to provide adequate fall protection while maintaining functionality and accessibility.

In this case, the correct choice reflects the lower minimum height requirement necessary to prevent falls from elevated surfaces. Building codes and safety regulations are designed to mitigate risks associated with height by mandating that guardrails adhere to these specified heights. Proper adherence to these guidelines not only protects workers on site but also ensures compliance with legal safety standards.

This height ensures that individuals are adequately safeguarded from potential falls, reinforcing the importance of maintaining proper guardrail specifications on elevated surfaces. The other options do not meet the minimum safety standards required for guardrails at elevated levels, making them unsuitable for construction safety compliance.