Dimensional Tolerances in Construction and for Surface Accessibility

2.1 Best practices for stating tolerances in the specifications

2.1.1 Clearly state the required installed tolerances for critical construction elements. In most cases, it is best to refer to industry standard tolerances or other industry documents when they exist. For example, ACI 117, Specifications for Tolerances for Concrete Construction and Materials and Commentary can be included without having to list the hundreds of individual tolerances given in the standard. If tolerances stricter than those given in an industry standard are required for a specific project, these should be stated, with the recognition that tighter tolerances may increase construction cost or time or both.

2.1.2 State the required tolerances for elements for which there are no industry standards. These may also include elements for which there is an industry tolerance for one aspect of the element but not others. For example, a product may have a manufacturing tolerance and an installed positional tolerance but not have an orientation tolerance for plumb.

2.1.3 State requirements for critical accumulated tolerances. These are instances where individual products and installation procedures may conform to industry standard tolerances but the final installed element may not meet regulatory, functional, or aesthetic requirements.