Dimensional Tolerances in Construction and for Surface Accessibility

Areas for further work

In the process of assisting the various organizations that represent surface materials and professional groups the following issues were identified as parameters that might be considered in the development of any industry standards. Of course, it was not expected that all of these would be included in any one industry's standards, but they do indicate the range and complexity of issues related to construction tolerances and accessibility, both with surfaces and any other aspect of accessible construction. This list may be useful for any future work.

Design issues:

• Existing industry tolerances

• Units of measure

• Measurement instruments

• Accuracy of instruments/measurement uncertainty

• Use of significant figures

• Metric conversions or dual unit standards

• Measurement of dimensions that involve two or more trades/materials

Construction issues:

• How/where to take measurements/precision of measurement

• Accuracy of construction/tolerances for individual materials

• Cost/time implications

• Influence of accepted local practices for construction

• Inspection/measurement protocols

• Effects of weather, such as curing and freeze - and - thaw on outdoor surfaces

• Maintenance/durability of surfaces

• Workforce training

Usability issues:

• Planarity

• Maneuverability

• Rollability/rolling

• resistance

• Jointed surfaces/vibration

• Cross slope

• Gaps

• Flatness lippage

• Slip resistance

In the end, most of these issues were not considered by the trade and material organizations that participated in this study or reference was simply made back to the ADA/ABA Guidelines. This may be due the time and effort required to consider them all or to the reluctance of an organization to commit to the development of standards that could have legal consequences.