Question: When engineers perform structural calculations on reinforced masonry walls, they assume precise placement of reinforcing steel. In actual construction, the reinforcing steel is often not so precisely placed. How far off can reinforcement be placed?

Answer:The Masonry Standards Joint Committee Specification for Masonry Structures (ACI 530.1/ASCE 6/TMS 602) in Section 3.4E.1 and the Uniform Building Code in Section 2104.5 set limits on how far reinforcement can be from the intended location and still be considered effective for walls and beams. The tolerance for spacing of vertical bars is ± 2 inches along the length of the wall. This tolerance depends on the distance between the face of the concrete masonry unit and the center of the bar, known as d. When d is less than 8 inches, the tolerance is ± 1/2 inch. When d is between 8 and 24 inches, the tolerance is ± 1 1/4 inches.