Glossary
Kiln-dried lumber
Also called: KD, KD19, kiln dried, S-DRY
Reviewed
Definition
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.
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.