A wooden pallet consists of a top deck, an optional bottom deck, and supports (stringers or blocks) that hold the decks apart and create openings for forks, all joined with fasteners. Standard terms for each element are defined in ISO 445, the pallet vocabulary standard, and understanding them makes specifications, inspections and repair instructions much easier to read.
The basic structure
Every pallet is a sandwich. A load-bearing top deck sits above a space for forks, and the space is created by supports. In most designs a bottom deck sits below, tying the supports together and spreading the load onto the floor or onto rack beams. Pallets with no bottom deck are called single-deck or skid-type pallets; see skids vs pallets for the difference.
The basic components, using ISO 445 style terminology, are:
| Term | Definition | Role |
|---|---|---|
| Top deck | The assembly of boards forming the load surface | Carries goods and distributes weight to supports |
| Bottom deck | The assembly of boards on the underside | Adds stiffness, stability and a wider base |
| Deckboard | A single board of a deck | Basic load-spreading element |
| Lead deckboard | The outer deckboard at the entry edge of the pallet | Takes fork and pallet-jack impact |
| Stringer | A continuous full-length support running between the decks | Main beam of stringer pallets |
| Block | A short, square-ish support | Spacer in block pallets |
| Stringerboard | A board running between blocks, parallel to the fork direction | Joins blocks and carries load in block pallets |
| Fork entry | The opening between supports where forks enter | Defines two-way or four-way access |
Deckboards
Deckboards form the working surface. Their thickness, width, spacing and species decide how much load a pallet carries and how well it protects products. Wider boards with small gaps support cartons more evenly; widely spaced narrow boards save wood but allow cartons to sag.
Several terms matter in practice:
- Lead boards are the end boards on the sides where forks or pallet trucks enter. They absorb the most abuse, so they are often wider or are the first boards to be replaced during repair.
- Inner boards are all deckboards between the lead boards.
- Spacing is the gap between boards. Bottom decks are often closed more tightly where pallet jacks must roll, and some pallet types have a continuous solid top deck.
- Overhang (or wing) refers to a deckboard or deck extending beyond the support. Overhang increases usable area but exposes boards to forklift damage.
Specific dimensions depend on the pallet standard. On the EPAL Euro pallet, the structure is 11 boards and 9 blocks fixed with 78 nails; details are in the Euro pallet and EPAL. On North American stringer pallets, decks typically use nominal 1 in boards, but specifications vary widely by grade and use.
Stringers
A stringer is a continuous beam, usually of solid lumber, that runs the length of a stringer pallet. Most North American 48 × 40 in pallets use three stringers: two outer and one center. The ends of the stringers carry the weight at the pallet edges, which is why stringer pallets must be inspected for splits.
Stringers can be modified for handling:
- Notches are cut-outs on the sides of the stringer, at the bottom, which let the forks of a forklift enter from the sides. A pallet with notched stringers is a partial four-way or "limited" four-way pallet; forks can enter from the sides but a pallet jack's wheels cannot always pass. See two-way vs four-way pallets.
- Chamfers are angled cuts at the bottom corners of stringers or deckboards that let wheels and forks slide onto the pallet and reduce snagging.
- Cut-outs and bevels may also be used to save weight.
Stringers also appear as the support in stringer vs block pallets, where their strength and cost advantages are compared with blocks.
Blocks and stringerboards
Block pallets replace continuous stringers with usually nine blocks arranged in three rows: corners, mid-sides and center. A stringerboard connects each row of three blocks; the Euro pallet has three of them, which together with five top and three bottom deckboards make up its 11 boards. Because blocks sit at spacing that clears the fork width, forks can enter from all four sides.
Blocks take compressive load and nails. They are made from solid wood, chipwood (pressed wood chips) or other composites. Block quality, including knots and splitting, strongly affects durability; see pallet blocks for materials and production.
Fasteners
Nails are the standard fastener. Pallets use hardened steel nails with helical (spiral) or annular (ring) shanks, which resist withdrawal far better than smooth nails as the wood dries and flexes. Staples, screws and bolts appear in specific designs, but nails are chosen for speed and cost. Length, diameter and head type are selected to match board thickness; the nail must pass through the deckboard and embed deeply into the support without splitting it.
Fastener quality is a main factor in whether a pallet survives repeated handling. Guidance on choice and spacing is given in pallet nails and fasteners.
Entry openings and dimensions
The fork entry is the free opening between decks. Overall pallet height is usually 100-160 mm (3.9-6.3 in), and the Euro pallet is 144 mm (5.7 in) high. Pallet length is conventionally the dimension parallel to the top deckboards, with width the second figure, which standards sometimes reverse, so the convention must be stated in the order.
The openings give pallets their entry classification:
- Two-way entry: forks enter two opposite sides only (stringer pallets without notches).
- Partial four-way: all four sides, but two only for forklifts (notched stringers).
- Four-way: all four sides for forks and pallet trucks (block pallets).
Why the terms matter
Standardized names remove ambiguity. A purchase specification that says "five top boards, three stringers, chamfered lead boards, ring-shank nails" can be built and inspected the same way anywhere. Quality systems and repair rules also use these terms, as in pallet repair, where a "broken lead board" or "split stringer" triggers defined actions.
Frequently asked questions
What is the difference between a stringer and a block?
A stringer is a long continuous beam running the length of the pallet, while a block is a short spacer. Pallets with stringers are usually two-way or partial four-way, and pallets with blocks are four-way.
What is a lead board?
A lead board is the outer deckboard at an entry edge of the pallet. It is the board most exposed to forklift impact, so it is often reinforced or replaced first.
What do notches and chamfers do?
Notches allow forks to enter a stringer pallet from the sides. Chamfers are angled cuts that help forks and pallet-jack wheels slide onto the pallet.
Why do pallet nails have spiral or ring shanks?
Their threaded or ringed shanks grip wood fibers, giving much higher withdrawal resistance than smooth nails, which is vital as wood moves with humidity.
Sources
- ISO 445:2013 Pallets for materials handling — Vocabulary — International Organization for Standardization
- How Much Load Can My Pallet Carry? — Virginia Tech Center for Packaging and Unit Load Design
- EPAL Euro Pallet (EPAL 1) technical data — European Pallet Association
- Pallet (EN 14943 definition) — PIARC Road Dictionary