Green lumber (pallets)
Also called: green wood, unseasoned lumber, wet lumber
Green lumber is freshly sawn wood that has not been dried, with moisture content above the fiber saturation point of about 28%. Many hardwood pallets are built from green lumber because drying adds cost.
In depth: Pallet lumber moisture: green vs kiln-dried, shrinkage, weight and mold
Green wood still holds free water in its cells as well as bound water in the cell walls. Pallet parts sawn from green cants are often nailed together within days, so the pallet dries in use.
Effects of building green
| Effect | Detail |
|---|---|
| Weight | A PDS example 48 × 40 in mixed hardwood weighed 59 lb (27 kg) green and 37 lb (17 kg) at 12% moisture |
| Shrinkage | About 1% of dimension for each 5% moisture lost below about 28% |
| Strength | Wood gets stronger and stiffer as it dries |
| Nail holding | Smooth nails driven green that dry in service keep only about a quarter of their withdrawal strength in the Uniform Standard (2012) equations; threaded nails are not penalized |
| Mold | Green wood in closed trailers, containers or warm storage can grow mold |
Why it matters
Green pallets are cheaper, but they are heavier to ship, can loosen as they dry, and can transfer moisture and mold to products and packaging. Many buyers (food, pharmaceuticals, export) specify a maximum moisture content, often 19%. Costco's pallet policy, for example, requires under 19% for containerized shipments. See pallet lumber moisture and pallet mold.
On a spec sheet
PDS records moisture content at manufacture, for example "Green". If you need dry wood, write a number, not just "dry".
Related
- 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%.
- GlossaryWhat does kiln-dried mean for pallets?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.
- 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.
- GuidesPallet mold: causes, prevention and what to do with moldy palletsPallet mold grows when wood stays above about 20% moisture in warm, still air: green pallets in containers, wrapped loads or covered yards. The fix is dry wood: specify kiln-dried pallets (19% or less), store them dry and ventilated, and check moisture before loading. HT alone does not prevent mold.
- 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.
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. 235 words.