Open web steel joists are typically used in construction to support which of the following?

Open web steel joists are structural units specifically designed to support loads in both floors and roofs in various types of buildings. They provide excellent strength-to-weight ratios, allowing for long spans which is beneficial in minimizing the need for additional columns or supports, enhancing design flexibility.

When used in floors, open web steel joists carry the weight of the flooring system, including loads from occupants and equipment. In roofing applications, they support roof systems, which may include insulation, waterproofing, and other membrane materials. Their design facilitates the management of load distribution effectively across larger areas, making them ideal for both scenarios.

Thus, the correct answer reflects the versatility of open web steel joists in construction, confirming their ability to support both floors and roofs efficiently.