Kiln-dried lumber
Kiln-dried (KD) lumber is wood dried in a heated kiln to a target moisture content, commonly 19% (KD19), 15% or 12%. Kiln drying reduces weight, shrinkage and mold risk, but a KD stamp alone does not show ISPM 15 compliance; that needs an HT mark.
Also called KD, KD19, kiln dried, S-DRY
Reviewed
Common targets
| Label | Target moisture content |
|---|---|
| KD19 (S-DRY) | 19% or less |
| KD15 | 15% or less |
| KD12 | 12% or less |
PDS also offers a post-assembly "Conditioning" entry such as "Kiln Dried - 19% EMC", meaning the finished pallet was dried after it was built.
Why specify kiln-dried
- Weight: mixed hardwood drops from about 4.37 to 2.91 lb per board foot (green vs kiln dried, nails included)
- Stability: most shrinkage happens before assembly, so dimensions and nails stay tight
- Mold: dry wood is far less prone to mold in containers
- Buyer rules: Costco requires moisture content below 19% for containerized shipments, and EPAL requires dry wood (confirm with the current guide)
Kiln-dried vs heat-treated
Heat treatment (HT) is a phytosanitary treatment: the core of the wood reaches 56 °C for 30 minutes. Kiln drying targets moisture. Wood marked KD-HT has had both, but a "KD" stamp by itself is not ISPM 15 compliance. See kiln-dried vs heat-treated.
Questions
- Is kiln-dried the same as heat-treated?
- No. Kiln drying lowers moisture; heat treatment kills pests to ISPM 15. Only an HT (or KD-HT) mark shows ISPM 15 compliance.
Related
- Heat treatmentHeat treatment (HT) heats pallet wood until its core reaches 56 °C for 30 minutes, the ISPM 15 treatment that lets wood pallets cross borders. Marked HT.
- Green lumberGreen lumber is wood that has not been dried, with moisture content above about 28%. Green mixed hardwood pallets weigh about 4.37 lb per board foot.
- Moisture contentMoisture content (MC) is the water in wood as a percent of its oven-dry weight. Dry pallet service means 19% MC or less; green wood is above about 28%.
- Kiln-dried vs heat-treated palletsKiln drying lowers moisture (often to 19%); heat treatment is the ISPM 15 export treatment (56 °C core for 30 min). KD alone is not ISPM 15 compliant.
- Load overhangLoad overhang is when product on a pallet extends past the pallet's edges. It leaves carton edges unsupported, cutting stacking strength and inviting damage.
- LoadSyncLoadSync is a free tool NWPCA released in 2013 that let pallet buyers define their load and handling requirements and send them to a PDS-licensed manufacturer.