Under what condition may materials be stored within 6 feet of a roof edge?

Materials may be stored within 6 feet of a roof edge if guard rails are erected at the roof edge. This requirement is based on the necessity to prevent falls, which pose significant risks on construction sites. Guard rails serve as a physical barrier that can help keep materials and workers safely away from the edge, minimizing the danger of accidental falls. They not only provide additional protection for those working nearby but also help prevent tools and materials from being dislodged and falling off the roof, which can also be hazardous to those below.

While other choices may have their own relevance in terms of safety protocols, they do not replace the need for established physical barriers like guard rails to manage the risks associated with working at heights. Safety officers' approvals, the use of harnesses, or the weight of materials do not inherently mitigate the fall risk as effectively as the presence of guard rails. Thus, the erection of guard rails at the roof edge is a critical safety measure that enables the safe storage of materials close to the edge.