01
Use physical separation and clear labels
Agree on distinct storage zones for each roof selection. Label them with the actual product reference and intended roof area, using a simple map the crew can follow. Avoid relying only on colored tape if the meaning is not documented. Keep original supplier labels where practical.
02
Control the handoff to installation
Have the foreman identify which stock is being drawn for each area before it reaches the roof. If material becomes mixed, pause allocation and consult the supplier and installer rather than guessing from appearance. Document the accepted resolution. This is especially important when a project includes retained slate, new matching slate, and a deliberately different selection for an addition.