What is the mortar joint thickness tolerance from the specified dimensions for a bed joint?

In masonry construction, the mortar joint thickness is critical for structural integrity and aesthetic appeal. The industry standard for bed joint thickness typically has a tolerance that allows for slight variations in mortar application to account for construction realities. A tolerance of 1/8" is commonly accepted, as it ensures that joints remain uniform while providing enough leeway for practical adjustments during installation. This thickness helps maintain the overall stability of the masonry assembly, allowing it to perform effectively under load while also contributing to the visual uniformity of the finished wall.

Other options present larger tolerances, which might not align with standard practices. A 1/4", 1/2", or even 3/8" tolerance would likely result in more pronounced variations in joint appearance and could lead to structural issues if joints are excessively thick. Thus, the 1/8" tolerance is the most appropriate answer in the context of optimal masonry standards.