01
Map distinct areas
Identify differences in material, layout, and details and connect them to dated records where possible. Mark uncertain dates as unknown instead of assigning an age from appearance alone. Ask the assessor to distinguish the physical condition of each area from its historical significance.
02
Develop a reasoned treatment plan
The appropriate approach may retain some alterations and change others, depending on the building and project goals. Have the relevant preservation professionals review those decisions. Keep the evidence and reasoning with the final drawings. A chronological map allows future owners to understand the roof's development without assuming that every difference is either original fabric or defective work.