The correct choice identifies that providing structural support for walls is not a purpose of a roof deck. A roof deck's primary role is to support the roof assembly, which includes the roofing materials themselves and any additional layers, such as insulation or waterproofing membranes.
A roof deck is engineered to bear the weight of the roof system, thus ensuring that it can withstand various loads, including those from snow, wind, and any mechanical equipment installed on the roof. Furthermore, it acts as a base for roofing materials, aiding in the proper installation and performance of the overall roofing system.
While moisture control and waterproofing are essential functions of a roof, these processes take place through the materials applied on top of the roof deck rather than the deck itself providing direct structural support to walls. The connection of the roof to the walls is achieved through other structural components, such as beams or columns, rather than relying on the roof deck for that purpose. This distinction clarifies why the option regarding structural support for walls does not align with the fundamental roles of a roof deck.