Based on standard industrial schedules and research data (such as from the USDA Forest Service or Forest Products Laboratory ), the following are approximate times for drying green timber to ~8% MC:
| Kiln Type | Typical Time Reduction vs. Air Drying | Typical Total Cycle | |-----------|----------------------------------------|----------------------| | Conventional (40–80°C) | 4–10× faster | 4–60 days | | High-temperature (>100°C) | 10–20× faster | 1–10 days (softwoods) | | Vacuum kiln | 5–15× faster than conventional | 5–20 days for hardwoods | | Dehumidification | 2–3× faster | 7–60 days | kiln seasoning time for timber
Industry rule: “The fastest drying schedule is the slowest one that meets quality standards.” Based on standard industrial schedules and research data
| Wood Species | Conventional Kiln (days) | Vacuum Kiln (days) | High-Temp (softwoods only) | |--------------|--------------------------|--------------------|-----------------------------| | Pine (southern yellow) | 3–5 | 2–3 | 1.5–2 | | Spruce | 4–6 | 2–4 | 2–3 | | Red Oak | 28–40 | 6–12 | Not recommended | | White Oak | 35–60 | 8–15 | Not recommended | | Maple (hard) | 20–30 | 5–9 | Not recommended | | Walnut | 20–25 | 4–7 | Not recommended | | Cherry | 15–20 | 3–6 | Not recommended | | Ash | 10–15 | 3–5 | 4–6 | kiln seasoning time for timber
The time required depends heavily on the , thickness , and initial moisture content . Average Kiln Drying Times by Timber Type