Mastery of Measurement

The conventional approach to specifying dimensional tolerances in architecture and construction is inadequate in the theater of premanufacturing large, complex architectural components. A new mindset, approach, and set of tools to design for construction is necessary to efficiently coordinate, fabricate, measure, and install unusual architectural geometries and implement modern methods of measurement such as laser trackers. Furthermore, considerations for actual installed conditions is crucial for some components where orientation, temperature, and lighting conditions can be much different in the manufacturing environment where parts are validated compared to the actual conditions components are exposed to once installed on a building. This is especially relevant for work requiring a tight fit, or high standards for alignment and fairness. Solutions to these challenges can be adapted from existing manufacturing practices such as Advanced Product Quality Planning, the system of Geometric Dimensioning and Tolerancing, and process/product validation with statistical analysis.

Fabrication of large, complex composite facade panels exposes many of these challenges. This study follows the process of fabricating such panels for a recent construction project with extremely high demands for dimensional tolerances, color matching, and installed fit. The disconnect between a traditional dimensional architectural specification (+/- dimensioning) and modern means of measuring and analysis (laser trackers) will be highlighted. Statistical analysis was performed to study process capability, and pave the way for targeted retooling and rethinking such as specialized positioners for holding work in "building position", reinterpreting the dimensional tolerances, and analytical color models for verifying color beyond just meeting the spec. This topic is relevant across the AEC pipeline starting with the architect who writes the specification, the fabricator who builds accordingly, and the installer who confronts the final tolerance stack-up and ultimate aesthetic evaluation of the outcome.