Start with one question
Define what the records need to resolve: the original tile profile, a later change to the roof, or the extent of a previous repair. NPS Preservation Brief 35 places historical research alongside physical investigation. Begin with existing research, then look for missing evidence. A broad search for every document can consume time without answering the question that affects the project.
Identify what each document represents
Record the author, date, building name, drawing or specification number, revision and archive location. Distinguish a preliminary proposal from an issued specification, a purchase record and a report of completed work. An instruction to supply a named tile is evidence of an intention; by itself it does not establish what was delivered or remains on the roof. Note missing pages and uncertain dates instead of silently filling the gaps.
Follow changes through time
Make a short chronology linking construction, additions and known repair campaigns. Compare dated photographs, written records and observations made by a qualified roofer or preservation specialist. A later replacement may resemble an earlier profile while using a different material or attachment. Treat a mismatch as a question to investigate. Do not assign a date or maker solely because one catalogue illustration looks similar.
Use a roof evidence register
For each question, keep five fields together: the documentary statement; its exact source and page; the corresponding roof area or sample; supporting or conflicting observations; and the remaining uncertainty. For example, an undated note naming a tile maker can be recorded as a lead awaiting confirmation from an invoice or safely obtained underside mark. This is a suggested project worksheet, not a finding about any particular roof. Keep original scans with their archive references so another reviewer can check your interpretation.
Separate historical evidence from today’s repair specification
GSA’s clay tile repair procedure HP070120, last modified July 1, 2026, is reference guidance for historic-property work. It calls for project review, documented conditions and appropriate product information. Neither that general procedure nor an old building specification supplies a universal repair detail. Have the responsible professional reconcile conservation objectives, the actual assembly, current product documentation and applicable project requirements before work proceeds.
Close the research loop
Summarize what the evidence establishes, what it only suggests and what still needs investigation. Attach the approved decision to the roof area it concerns, with the reviewer and date. Keep later discoveries and repair photographs in the same record rather than rewriting the earlier evidence. NPS documentation guidance emphasizes research objectives and evaluation of sources; a clear account of uncertainty makes the record useful to the next owner or project team.
Further reading & technical sources
- National Park Service · Preservation Brief 35 (1994), architectural investigation ↗
- National Park Service · Historical Documentation Guidelines ↗
- GSA · Repair and reattachment of clay roof tile ↗
Consult the current product documentation and local requirements for your project. These introductions are not installation specifications.
More tile roofing guides
- Reading historic clay tile maker’s marks
- Documenting a historic clay roof before work
- Resolving conflicting clay roof documents
Tile Roofing USA editorial guide · Published October 29, 2026.