General Contractor Practice Exam

What is the minimum number of No. 5 rebar required for door and window openings in a concrete wall?

1. 1

2. 2

3. 3

4. 4

The correct answer is: 2

In concrete construction, particularly when dealing with door and window openings, the structural integrity is critical. No. 5 rebar, which is 5/8 inch in diameter, is commonly used for reinforcing concrete. The minimum number of bars required is primarily determined by the need to ensure that the concrete can withstand tensile forces, particularly in areas where openings are present. In typical building codes and standards, such as those outlined in the ACI (American Concrete Institute) guidelines, it is specified that at least two No. 5 rebar are needed for proper reinforcement across the top and bottom regions of door and window openings. This allows for adequate load distribution and helps to reduce cracking and potential structural failure. While other options present a number of bars, selecting two provides a balance between strength and practical application. More bars could be used in specific engineering designs or unusual spans, but the minimum requirement is set at two to ensure foundational support and durability in the concrete wall surrounding the openings.