I plan lead times and inventory around drying, and I was taught the old ‘one year per inch’ air-drying rule. Does anyone know its origin and assumptions, because our 5/4 white oak in central Ohio routinely needs 14–16 months to hit about 12% MC, which pushes install schedules.
Old FPL/USDA Wood Handbook-era rule of thumb, @OP — the “one year per inch” assumed temperate summers, good airflow under cover, and drying to local EMC, not 12% on slowpokes like white oak; it’s more folklore than physics. Your 14–16 months for 5/4 in central Ohio tracks; I’ve cut that by a couple months with end sealer, 12–16 in sticker spacing, and a cheap box fan under a roof. If schedules are tight, air‑dry to about 20% then finish in a small DH kiln; the Wood Handbook backs this up: Forest Products Laboratory | US Forest Service Research and Development.