The baseline comes from Realie.ai: beds, baths, lot size, construction type, tax and assessment records, transfer history. Federal hazard data is layered on from FEMA, joined on the county FIPS code rather than the address, because FEMA's index doesn't resolve any finer than county. The proprietary layer is the owner's own ledger: dated maintenance and improvement records, cost, contractor, receipt photos. The part no API can supply, and the reason anyone would trust the report.