Dimensional Tolerances in Construction and for Surface Accessibility

2.3 Best practices for stating how compliance will be verified

2.3.1 Define the measurement protocols to be used to check for compliance with the tolerances and standards. This may include where measurements are made, how many should be made, and the number or percentage of measurements that must fall within the limits to be considered acceptable. For example, specifications may include limits on the number of local variations (dips and humps) on an accessible ramp to a maximum of 10 percent slope for no more than 20 percent of the measurements taken. If industry standards exist for measurement protocols, these should be referenced.

2.3.2 Define the measurement tools that should be used. The acceptable tools should be selected based on the accuracy required and a reasonable balance between the accuracy of the tool and the time, cost, and experience required for measurement. For example, floor profilers can provide a very accurate measurement of surface flatness but are expensive and require training to use. For exterior surfaces, a surveyor's transit or digital inclinometer may provide acceptable measurement for the same task.