Split (lumber defect)
Also called: end split, check, crack
A split is a lengthwise separation of wood fibers that runs through a board, usually from an end or a nail. Pallet lumber grades limit split length, and splits at joints are a main cause of pallet repair.
In depth: Pallet repair: methods, standards and when a pallet is not worth fixing
Splits start at board ends, where drying is fastest, or where a nail wedges the fibers apart. A check is a similar separation that does not go all the way through. Splits get longer as green wood dries and as the pallet is handled.
Limits in the Uniform Standard (2012)
| Part | Reusable | Single-use |
|---|---|---|
| Deckboards | Up to 1/3 of the length | Full length |
| Stringers, horizontal split | Less than 4 in (102 mm) or 2 × the width | Less than 4 in or 2 × the width |
| Stringers, vertical split | Up to 1/2 of the length |
At assembly, the standard allows at most one open split with a visible nail shank per connection, and on at most one third of the components.
Why it matters
A split at a joint lets the nail pull out, and a split lead board or stringer end is one of the most common reasons a pallet is repaired or rejected. Ways to reduce splitting include lower-density species, smaller wire diameter, blunt-point or staggered nails, keeping nails away from board ends and edges, and laminated or composite blocks on block pallets.
On a spec sheet
Splits are controlled through the lumber grade and the assembly requirements. For used pallets, split boards are graded in the inspection criteria. See pallet inspection.
Related
- GlossaryLumber grade (pallet lumber)A lumber grade is a quality class that limits defects such as knots, wane, splits and decay in pallet parts. PDS uses Select, Premium, Standard, Utility and Economy, often as '&BTR' mixes such as Standard & Better.
- GlossaryKnot (lumber defect)A knot is the portion of a branch embedded in a board. Knots weaken wood by disrupting the grain, so pallet lumber grades limit their size and number, with stricter limits for unsound (loose or decayed) knots.
- GlossaryJoint (pallet connection)A joint is the fastened connection where a deckboard or stringerboard crosses a stringer or block. Its strength depends on the number and type of fasteners, the wood density and the moisture content.
- GuidesPallet repair: methods, standards and when a pallet is not worth fixingPallets are repaired by replacing broken deckboards, reinforcing cracked stringers with a companion stringer, plug or metal plate, and replacing damaged blocks, following ISO 18613 and the Uniform Standard. Repaired pallets are weaker than new, need re-treatment for export, and some retailers refuse them.
- GuidesPallet inspection: an incoming inspection checklist for new and used palletsInspect incoming pallets against a written spec. Check a sample from every delivery for size, board count and thickness, broken boards or stringers, protruding nails, moisture, mold, stains and the ISPM 15 stamp. Reject failures, record why, and share the results with the supplier.
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. 233 words.