No permits, no seller disclosure, no idea? Six visible signs get you a solid age range and how many years you probably have left in the New Mexico sun. Free — from an independent inspector, not a contractor trying to sell you one.
Only relevant for shingle roofs — pick 'not applicable' otherwise.
High-desert UV and hail age asphalt shingles roughly 30% faster than the manufacturer's stated life. Granule loss, edge curl, and faded color are the three most reliable ground-level tells. Tile and metal age differently — they usually fail at flashings and fasteners long before the field material does.