01
Recreate the important view
Ask the designer to identify the elevations and public viewpoints that most influence the roof's appearance. Compare a representative selection of slates near the building and at a useful angle. Consider how the roof relates to masonry, trim, and neighboring roof sections. Close-up texture still matters, but it should not be the only basis for the choice.
02
Document the visual priorities
Record whether the goal is a quiet uniform field, a varied blend, or a deliberately textured surface. Use photographs to capture the approved arrangement, with physical samples retained as the reference. If the proposed size or thickness changes, revisit the overall effect. A substitution can preserve a color family while altering the shadow lines and scale that made the original selection suitable.