Pallet blocks are the short square or rectangular supports that separate the top and bottom decks of a block pallet and create fork openings on all four sides. They are made from either solid wood or chipwood, also called compressed or pressed wood blocks, and the choice affects cost, consistency, nailing behavior and ISPM 15 treatment.
What blocks do
In a block pallet, nine blocks (three per row) carry the load from the top deck to the bottom deck. Boards are nailed through into the blocks, so the block must hold nails securely, resist crushing and stay dimensionally stable. Because forks and pallet trucks hit blocks during handling, corner blocks also absorb knocks and are a common place for damage; see pallet anatomy for terminology and stringer vs block pallets for how block designs differ.
On the EPAL Euro pallet, the blocks are fixed in size and position, and their quality is part of the EPAL technical regulations. All four corner blocks carry the EPAL trademark branding, and the central block carries a mark with licence number and production date, details covered in EPAL markings.
Typical dimensions
Block sizes follow the pallet design. For the 1200 × 800 mm (47.2 × 31.5 in) Euro pallet, the usual blocks are:
| Block | Typical footprint | Height |
|---|---|---|
| Corner block | 145 × 145 mm (5.7 × 5.7 in) | 78 mm (3.1 in) |
| Middle block | 145 × 100 mm (5.7 × 3.9 in) | 78 mm (3.1 in) |
Height is what sets the fork opening between the decks. A block manufacturer's range lists a 78 mm high block as the EPAL repair block, and a wide range of other footprints and heights from about 60 to 120 mm for other pallet designs. Always check the current EPAL technical regulation for exact tolerances if producing or repairing EPAL pallets, because the licence requires approved components.
Non-EPAL block pallets vary widely: industrial 1200 × 1000 mm pallets, display pallets, and many custom sizes use their own block dimensions. See industrial pallet sizes.
Solid wood blocks
Solid wood blocks are cut from lumber, offcuts or recycled timber, usually softwood such as spruce or pine, or sometimes hardwood.
Advantages - Low capital cost: can be cut from offcuts with ordinary saws - Good nail retention and familiar behavior - Easy to repair and recycle - Available anywhere lumber is processed
Disadvantages - Variable quality: knots, splits, grain direction and moisture differ between blocks - Risk of splitting when nailed close to the end grain, especially when dry - Can crack or rot if damp - Solid wood falls within ISPM 15, so blocks in export pallets must be treated and the pallet marked; see ISPM 15 explained - Mixed species and recycled material raise inspection effort
Quality rules for acceptable defects in blocks are set in the pallet specification and in EPAL quality classes when repairing.
Chipwood (compressed wood) blocks
Chipwood blocks are made by chipping wood, mixing it with a binder, and pressing it under heat into a dense, uniform profile that is cut into blocks. The raw material can be sawmill residues, thinnings or recycled wood, which makes chipwood a use for low-value wood fiber that would otherwise be burned or discarded; see pallet wood waste and biomass.
Production in outline:
- Chipping and screening: wood is reduced to chips or strands and sorted by size.
- Drying: chips are dried to a controlled moisture before gluing.
- Blending with adhesive.
- Pressing: the mat is compressed into a billet or profile under heat and pressure. Equipment is covered in chipwood block presses.
- Curing and cooling: to stabilize the material.
- Cutting and calibration to the required block size, often with a drilled hole or surface treatment for nail guidance.
Typical advantages reported by producers include uniform density, no knots, reliable nail withdrawal resistance, and resistance to cracking. They also accept inkjet printing and QR code marking.
Limitations: higher cost than offcut blocks per unit, dependence on glue (which brings emission and recycling questions), sensitivity to prolonged wetting if the grade is not moisture-resistant, and need for approved supply in systems such as EPAL.
ISPM 15 and chipwood
ISPM 15 regulates wood packaging made from raw wood. Wood that has been processed with glue, heat and pressure into a material such as particleboard is outside its scope. Block manufacturers therefore describe chipwood blocks as "no-solid wood" under ISPM 15, meaning that the blocks need no heat treatment or fumigation themselves. Note that the pallet is only exempt if all its parts are processed wood; a pallet with chipwood blocks but solid-wood boards still needs treatment and marking for export. See ISPM 15 exemptions.
Comparison
| Feature | Solid wood block | Chipwood block |
|---|---|---|
| Raw material | Lumber or offcuts | Wood chips or recycled fiber with adhesive |
| Consistency | Variable | High |
| Splitting tendency | Higher near nails | Low |
| Moisture sensitivity | Rot, mould if wet | Swelling at edges if wet |
| ISPM 15 | Treatment required | Exempt as processed material |
| Cost position | Low where offcuts are available | Usually higher unit cost, lower variability |
| Repairability | Easy | Requires correct replacement blocks |
| End of life | Reuse, chip or burn | Chip or energy recovery |
Moisture and storage
Blocks should be dry and stored under cover. Solid wood blocks that are too wet can shrink and loosen nails, and they invite mould; see wood moisture content. Chipwood blocks should be kept dry to avoid edge swelling. EPAL requires that wood be dried to prevent mould growth, but the specific moisture limits are laid down in its technical regulations.
EPAL and wood-chip blocks
EPAL permits wood-chip blocks in its Euro pallets, provided they meet the technical regulations. In April 2024, EPAL held its first European conference of manufacturers of EPAL wood-chip blocks in Warsaw. The event brought together producers, 18 of which were wood-chip block makers, with three EPAL-accredited testing institutes, to present drafts of new technical regulations on legal requirements and testing methods. EPAL stresses that the blocks are made from recycled wood or sawmill residues and can be returned into new blocks at end of life. A plant planning to use chipwood blocks in EPAL pallets should confirm with EPAL which block producers and products meet the current technical regulation.
Choosing blocks
- For EPAL production and repair: use only approved blocks of the correct dimensions.
- For general pallets: consider solid offcut blocks where lumber is cheap, and chipwood where uniformity or an ISPM 15-exempt structure is wanted.
- For automated lines: uniform blocks feed and nail more reliably.
- For hygiene-sensitive uses: dense, knot-free blocks resist splintering; see food safety pallets.
Frequently asked questions
What size are the blocks on a Euro pallet?
Standard Euro pallet blocks are 78 mm high, with corner blocks about 145 × 145 mm and middle blocks about 145 × 100 mm. Licensees should verify the exact tolerance in EPAL's technical regulation.
Are chipwood blocks allowed on EPAL pallets?
Yes, if the blocks meet EPAL's technical requirements and come from approved producers.
Do chipwood blocks need ISPM 15 treatment?
No, because they are processed wood material. However, any solid wood parts of the same pallet still need treatment and marking.
Which block type is stronger?
Strength depends on grade and density. Chipwood is more uniform, while good solid wood can be equally strong but with higher variation.
Sources
- EPAL Euro Pallet Quality Characteristics — European Pallet Association
- First conference of European manufacturers of EPAL wood-chip blocks — European Pallet Association
- Euroblock pallet block product range and data — Pfeifer Group
- EUR-pallet — Wikipedia
- Regulation of wood packaging material in international trade (ISPM 15) — International Plant Protection Convention