What does kiln-dried mean for pallets?
Also called: KD, KD19, kiln dried lumber
Kiln-dried (KD) lumber has been dried in a heated kiln to a target moisture content, most often 19% or less (KD19). Kiln drying reduces weight, shrinkage and mold risk, but a KD stamp alone does not show ISPM 15 compliance.
In depth: Heat treated vs kiln dried pallets: what the stamps mean
Kiln drying removes water from lumber with controlled heat and airflow. Lumber is dried to a target moisture content, and grade stamps show it, for example "KD19" or "S-DRY" (surfaced dry, 19% or less).
Common targets
| Designation | Moisture content |
|---|---|
| KD19 / S-DRY | 19% or less |
| KD15 / MC15 | 15% or less |
| KD12 | 12% or less |
| Green (not dried) | Above about 28% |
KD vs HT
| Kiln-dried (KD) | Heat treated (HT) | |
|---|---|---|
| Goal | Lower moisture | Kill pests under ISPM 15 |
| Requirement | Target moisture % | 56 °C (133 °F) core for 30 min |
| Proof | Lumber grade stamp | IPPC mark with HT code |
| Export compliance | No, not by itself | Yes |
A pallet marked KD-HT is both. See heat treated vs kiln dried and KD-HT.
Why it matters
KD pallets weigh less, shrink less after assembly, and resist mold. PDS can also apply a "Conditioning" treatment after assembly, for example "Kiln Dried – 19% EMC", which dries the whole pallet rather than the lumber. Wood can regain moisture in storage, so drying at manufacture does not guarantee moisture at delivery.
On a spec sheet
State the maximum moisture content, whether it applies to the lumber or the assembled pallet, and how it will be checked (moisture meter at receiving).
Frequently asked questions
Is kiln-dried the same as heat treated?
No. Kiln drying targets a moisture content. Heat treatment under ISPM 15 targets a core temperature of 56 °C for 30 minutes and is proven by the IPPC mark with the HT code. A pallet can be both, marked KD-HT.
What moisture content is kiln-dried pallet lumber?
Most kiln-dried lumber is dried to 19% or less (KD19). Some buyers ask for 15% or 12% for sensitive products.
Do kiln-dried pallets get moldy?
Much less often than green pallets, but dry wood can take up moisture again in wet storage or humid containers and then grow mold.
Related
- ComparisonsHeat treated vs kiln dried pallets: what the stamps meanHeat treatment (HT) heats the wood core to at least 56 °C for 30 minutes to meet ISPM 15 for export. Kiln drying (KD) lowers moisture content, typically to 19% or less, to reduce mold, shrinkage and weight. Choose HT for international shipping, KD for moisture control, and KD-HT when you need both.
- GlossaryMoisture content (pallet lumber)Moisture content (MC) is the weight of water in wood expressed as a percentage of the wood's oven-dry weight. Pallet specs usually call for 19% or less when dry wood is needed; green lumber is above about 28%.
- GlossaryKD-HTKD-HT indicates wood that is both kiln dried (KD), dried to a target moisture content, and heat treated (HT) to ISPM 15. Only HT is an ISPM 15 treatment code; KD describes moisture and does not by itself make a pallet export compliant.
- GlossaryWhat is heat treatment (HT) for pallets?Heat treatment (HT) is the ISPM 15 method of heating wood packaging until the whole profile of the wood, including its core, reaches at least 56 °C for 30 continuous minutes. Treated pallets carry the IPPC mark with the code HT.
- GuidesPallet lumber moisture: green vs kiln-dried, shrinkage, weight and moldGreen pallet lumber can hold 50–80% moisture; kiln-dried (KD) lumber is dried to about 19% or less. Drier wood is lighter, stiffer and far less prone to mold, but green wood nails more easily and costs less. Heat treatment (HT) for ISPM 15 kills pests; it does not dry the pallet. Specify moisture separately.
- GuidesHeat-treated pallets (HT): what they are, when you need them, and costA heat-treated (HT) pallet's wood core was held at 56 °C (133 °F) for 30 minutes under ISPM 15, then stamped with the IPPC mark and HT. Most countries require it on wood pallets crossing their border. It adds roughly $1–3 per pallet (2026 US estimate) and kills pests; it does not dry the wood.
More in Materials
- GlossaryBark (on pallet lumber)Bark is the outer layer of a tree trunk. ISPM 15 requires wood packaging to be made from debarked wood, allowing only small remnants: pieces under 3 cm wide of any length, or wider pieces with a surface area under 50 cm².
- GlossaryCant (pallet lumber)A cant is a log that has been sawn flat on two or four sides. In the pallet industry it usually means the low-grade center of a hardwood log, left after grade lumber is cut from the outside, which is resawn into pallet parts.
- GlossaryComposite block (pallet)A composite block is a pallet block made from wood chips, particles or fibers bonded with resin under heat and pressure. It does not split like solid wood and, as processed wood, is exempt from ISPM 15 on its own.
- GlossaryCorrugated fiberboard (pallets and slip sheets)Corrugated fiberboard is a board made of a fluted paper medium glued between flat paper liners. It is used for boxes, and in pallet work for corrugated paper pallets, slip sheets, tier sheets and pallet runners.
- GlossaryCut stock (pallet components)Cut stock is lumber already sawn to the finished thickness, width and length of pallet parts, such as 5/8 × 3-1/2 × 40 in deckboards, ready for nailing. It is also called pallet stock or shook.
- GlossaryDouglas-fir (pallet lumber)Douglas-fir is a dense, strong softwood from western North America, also grown in Europe. It is species class 11 (Douglas-fir–larch) in the Uniform Standard and PDS, and class 33 in the European species list.
Last reviewed 2026-09-24. 244 words.