Final answer:
a. 6-inches. The steel lintels on masonry walls should be at least 6 inches wider than the opening on either side to provide stability and distribute weight.
Step-by-step explanation:
The steel lintels on masonry walls should be at least 6 inches wider than the opening on either side. This extra width provides stability and helps distribute the weight of the wall above the opening.
Steel lintels are structural supports that span across the top of an opening in a masonry wall, such as a door or window. They help transfer the weight above the opening to the adjacent masonry walls.
By having the lintels wider than the opening, it ensures that the load is evenly distributed and helps prevent any sagging or cracking of the masonry. Therefore, the correct answer is option a. 6-inches.