Pallet lumber: species, grades and moisture
Pallet lumber is specified by three things: species class (from Annex B of the Uniform Standard), grade, and moisture content at manufacture. In North America the common choices are mixed Eastern hardwoods, oak, southern yellow pine, SPF and Douglas fir, and weight runs from about 3.2 lb per board foot for green SPF to about 5.3 lb for green oak.
Reviewed
On this page
How pallet lumber is specified
Pallet parts are usually cut to size from cants or rough lumber, a product the industry calls shook, rather than bought as finished dimension lumber. A pallet spec therefore describes the lumber with three properties rather than a trade size:
- Species class: a number from Annex B of the Uniform Standard for Wood Pallets, also used by PDS. A spec can list a mix of up to five class, grade and percent rows.
- Grade: the minimum quality, such as Standard &BTR. See lumber grades.
- Moisture content at manufacture, such as green or kiln dried to 19%. See moisture content.
Dimensions on the drawing are always actual, not nominal. See nominal vs actual lumber.
Common species classes
| Class | Group | Sort group | Examples |
|---|---|---|---|
| 1 | High-density Eastern hardwoods | Medium/high density | beech, ash, birch, hickory, hard maple |
| 3 | Medium-density Eastern hardwoods | Medium/high density | soft maple, sweetgum, sycamore, tupelo |
| 7 | Low-density Eastern hardwoods | Low density | aspen, basswood, cottonwood, poplar |
| 21 | Eastern oaks | Medium/high density | red oak, white oak |
| 29 | Yellow poplar | Low density | |
| 11 | Douglas fir-larch | Medium/high density | |
| 12 | Hem-fir | Low density | |
| 13 | SPF and similar softwoods | Low density | spruces, firs, eastern white pine, eastern hemlock |
| 14 | Low-density softwoods | Low density | cedars |
| 22 | Southern yellow pine | Medium/high density | loblolly, longleaf, shortleaf, slash |
European and other international species have their own classes (31 to 37, and 41 to 46). The sort group matters for nail choice and for some buyer rules; Home Depot, for example, is documented as excluding classes 7 and 14.
Species compared in palletdesign.ai
palletdesign.ai offers five species. The figures below are the engine's default assumptions, applied to the same GMA-style 48 x 40 stringer pallet (13.5 board feet, 3 notched 1-3/8 x 3-1/2 in stringers).
| Species | Allowable bending stress (psi) | lb per board foot, green / KD19 | GMA weight, green / KD19 | Lumber price per MBF |
|---|---|---|---|---|
| Mixed hardwood | 1,100 | 4.37 / 2.91 | 59 / 39 lb | $700 |
| Oak | 1,200 | 5.25 / 3.90 | 71 / 53 lb | $850 |
| Southern yellow pine | 1,300 | 4.45 / 3.40 | 60 / 46 lb | $750 |
| SPF | 850 | 3.24 / 2.30 | 44 / 31 lb | $800 |
| Douglas fir | 1,150 | 3.90 / 3.00 | 53 / 40 lb | $900 |
How to read this table:
- Bending stress values are the conservative allowable values palletdesign.ai uses for indicative checks. On the same design, the indicative bending check scales with this value: oak checks about 9% stronger than mixed hardwood, SYP about 18% stronger, Douglas fir about 5% stronger and SPF about 23% weaker. The check catches clearly weak designs; ratings come from a PDS analysis or physical testing.
- Weights include nails. The mixed hardwood and SPF factors are calibrated against published PDS sheets; the others come from species density tables.
- Prices are the engine's default assumption for green, standard-grade stock, not market quotes. Kiln drying adds 15% in the estimate.
- The indicative beam check is a simple, deliberately conservative screen (uniform load, 2 in of bearing on each beam) that catches clearly weak designs. It is not a substitute for a PDS analysis or an ASTM D1185 test.
Choosing a species
- Weight-sensitive or export loads: lighter softwoods (SPF) or kiln-dried stock cut freight weight.
- Heavy or racked loads: denser species (oak, SYP, high-density hardwoods) give more bending strength and nail holding.
- Cost: regional supply matters as much as species. Mixed hardwood is typical in the East, SYP in the South, and SPF and Douglas fir in the North and West.
- Buyer rules: check retailer guides for banned classes and moisture limits.
Hardwood vs softwood at a glance
| Hardwoods (mixed, oak) | Softwoods (SYP, SPF, Douglas fir) | |
|---|---|---|
| Typical form | Cut-to-size shook from cants | Often dimension lumber (2x4, 1x6) |
| Typical stringer | 1-1/4 or 1-3/8 x 3-1/2 in | 1-1/2 x 3-1/2 in |
| Usual nail | Helical | Annular for most softwoods |
| Often supplied | Green | Kiln dried |
Nails follow the species
Helically threaded nails are recommended for medium- and high-density hardwoods. Annularly threaded (ring shank) nails are recommended for low-density hardwoods and most softwoods. See pallet nails.
Questions
- What wood is used for pallets?
- In North America mostly mixed Eastern hardwoods, oak, southern yellow pine, SPF and Douglas fir. Specs describe them by Uniform Standard species class, grade and moisture content.
- What is the strongest common pallet lumber?
- Of the five species palletdesign.ai offers, southern yellow pine has the highest allowable bending stress in the engine (1,300 psi), followed by oak (1,200 psi). Actual capacity depends on grade, dimensions and nails.
- How much does pallet lumber weigh?
- Including nails, about 3.2 lb per board foot for green SPF up to about 5.3 lb for green oak. Kiln drying to 19% cuts that by roughly a quarter to a third.
Related
- Pallet lumber gradesPallet lumber grades set limits on knots, wane, splits, decay and slope of grain. Reusable pallets need roughly PDS Standard grade; single-use roughly Economy.
- Pallet lumber moisture contentPallet lumber moisture content drives weight, shrinkage, mold and nail holding. Kiln drying to 19% (KD19) cuts a GMA pallet from about 59 lb to about 39 lb.
- Mixed hardwood pallet lumberMixed hardwood pallet lumber blends high, medium and low-density Eastern hardwoods. It weighs about 4.37 lb per board foot green, 2.91 kiln dried.
- How much does a wood pallet weigh?A standard 48x40 GMA-style wood pallet weighs about 59 lb in green mixed hardwood and about 39 lb kiln dried. How to calculate pallet weight from board feet.
- How to calculate board feet in a palletBoard feet = thickness x width x length (inches) / 144, summed over every part. A 48x40 GMA-style pallet has 13.5 board feet. Step-by-step worked example.
- Oak pallet lumberOak pallet lumber (red and white oak, species class 21) is dense and strong: about 5.25 lb per board foot green and 3.9 kiln dried, including nails.
Sources
- NWPCA Uniform Standard for Wood Pallets (2012), Annex B species classes and Table 7 sort groups
- PDS, Guide to understanding the PDS specification and analysis
- Engineering ToolBox, green and kiln-dried lumber weights
- palletdesign.ai engine, calc.ts and capacity.ts default assumptions