01
Create a visual map
Photograph the complete pattern square-on where professional access permits, then capture smaller sections with location labels. Record the sequence of colors and shapes and identify repeated units. Have dimensions and course relationships measured by the contractor. Do not rely on one distant photograph that loses the details needed to distinguish the pattern from ordinary variation.
02
Link the map to replacement material
Label representative samples and any pieces selected for retention. Ask the installer how the pattern will be set out and checked during the repair. If some original information is missing, document the proposed interpretation for approval before work begins. Keep the record after completion; it can make a later small repair possible without repeating the entire investigation.