Pallet glossary
Pallet vocabulary, from deckboard to wane, with the typical dimensions and the standard that defines each term.
92 pages
A
B
Bill of materials
A pallet bill of materials (BOM) is the list of every component in one pallet, with its size, material and quantity: deckboards, stringers or blocks, stringerboards and fasteners. A GMA-style 48x40 BOM lists 15 wood parts (7 top boards, 5 bottom boards, 3 stringers) and 84 nails, about 13.5 board feet in all.
Block
A block is a rectangular, square or cylindrical spacer between the top and bottom decks of a block pallet, specified as width x height x length. Most block pallets use 9 blocks in a 3 x 3 grid; the EPAL 1 Euro pallet uses 145 x 100 x 78 mm and 145 x 145 x 78 mm blocks.
Block class
Block class is one of the two pallet classes in the Uniform Standard and PDS: pallets whose top deck is carried on blocks, usually nine in a 3 x 3 grid, tied together by stringerboards. Block-class pallets, such as the EPAL Euro pallet and North American 48x40 pooled pallets, allow four-way entry.
Block stacking
Block stacking is a warehouse storage method in which unit loads are stacked directly on top of one another on the floor, arranged in rows or blocks without racking. The pallets low in each stack carry the weight of every load above them, so stack height is a key design input.
Board foot
A board foot is a volume of wood equal to 144 cubic inches (1 in x 12 in x 12 in). Pallet board feet are calculated as thickness x width x length in inches divided by 144, using actual dimensions; a GMA-style 48x40 pallet contains about 13.5 board feet.
Bottom deck
The bottom deck is the set of deckboards (or a panel or perimeter frame) on the underside of a pallet, which bears on the floor, conveyor or the unit load below. A GMA-style 48x40 has 5 bottom boards: two 5-1/2 in lead boards and three 3-1/2 in interior boards. Single-face pallets and skids have no bottom deck.
Butted boards
Butted boards are deckboards placed tight against a lead board with no gap between them. The Uniform Standard treats two butted 4 in boards as equivalent to one 6 in board, so butting is a way to build a wide lead board from narrower stock.
C
Cant
A cant is a log that has been squared on two or more sides at the sawmill. In the hardwood industry the cant is often the lower-grade center of the log left after the higher-grade boards are taken, and it is a main raw material for pallet parts.
Chamfer
A chamfer is a bevel cut along the edge of a bottom deckboard so pallet-jack wheels can roll up and over the board instead of striking it. The Uniform Standard calls for a 35 to 45 degree bevel at least 12 in long that stays out of the nail connections.
Clinched nail
A clinched nail is driven completely through the pieces being joined and bent over on the far side, so it holds by the bend rather than by friction. The Uniform Standard requires clinched pallet nails to fully penetrate the stack and be at least 1/4 in longer than its thickness.
Combo pallet
A combo pallet is built from a mix of new and recycled components, for example new stringers with recycled deckboards. In the pallet classification it is Remanufactured/Combo, and like other remanufactured pallets it must be re-treated and re-marked to ISPM 15 for export.
Companion stringer
A companion stringer is a repair component fastened alongside a damaged stringer to restore its strength, instead of replacing the stringer outright. The Uniform Standard lists companion stringers with plugs, C-blocks and metal connector plates as recognized pallet repair methods.
CP pallet
CP pallets are nine standard block pallet designs, CP1 to CP9, used by the chemical and plastics industry in Europe. Each type has a fixed size and construction: CP1 to CP5 are runner types, while CP6 to CP9 have perimeter or frame bottoms, for example CP1 at 1000 x 1200 mm and CP3 at 1140 x 1140 mm.
Creep
Creep is the gradual increase in deflection of a pallet that carries a load over time, even though the load does not change. Wood and especially plastic pallets creep, which is why PDS reports deflection after 30 days and why test standards include hold periods.
Cruciform base
A cruciform base is a block-pallet bottom deck made of a perimeter frame plus center connector boards that cross in the middle, forming a cross (cruciform) pattern. It supports the center block in both directions and keeps full four-way entry.
Cut list
A cut list is the production list of how many pieces of each size must be cut for an order: parts per pallet multiplied by the number of pallets. For 1,000 GMA-style 48x40 pallets it reads 8,000 pieces at 5/8 x 3-1/2 x 40, 4,000 at 5/8 x 5-1/2 x 40 and 3,000 stringers at 1-3/8 x 3-1/2 x 48.
D
Deck coverage
Deck coverage is the share of a pallet deck's area that is covered by boards, the rest being gaps. It equals total board width divided by deck length: a GMA-style 48x40 top deck (two 5-1/2 in and five 3-1/2 in boards) covers 28.5 of 48 in, about 59%, and its bottom deck about 45%.
Deck gap
A deck gap is the open space between two neighboring deckboards. With the end boards flush and interior boards equally spaced, the gap is (deck length minus total board width) divided by (number of boards minus 1): a GMA-style 48x40 top deck works out to (48 - 28.5) / 6 = 3.25 in.
Deck mat
A deck mat is a pre-assembled unit of deckboards and stringerboards on a block pallet, usually fastened with clinched mat nails, which is then nailed down onto the blocks. Typical mat nails are 1-5/8 in smooth nails clinched over on the underside.
Deckboard
A deckboard is a top or bottom deck element laid perpendicular to the stringers or stringerboards, specified as thickness x width x length. On a GMA-style 48x40 stringer pallet the interior deckboards are typically 5/8 x 3-1/2 x 40 in and the lead boards 5/8 x 5-1/2 x 40 in.
Deflection
Deflection is how far a pallet bends or sags under load, measured at the point of greatest movement. Common limits are about 1.9 to 2% of the span in rack storage (roughly 0.75 in on a 44 in span), 1.5 to 2% on the floor, and 0.5 in or less for automated warehouses and AS/RS.
Dielectric heating
Dielectric heating (DH) is an ISPM 15 treatment that uses microwave or radio-frequency energy to heat wood packaging to at least 60 °C for one continuous minute throughout the wood profile. Treated wood carries the code DH on its ISPM 15 mark.
Double-face
A double-face pallet has both a top deck and a bottom deck. It is either non-reversible, with a lighter bottom deck (a GMA-style 48x40 has 7 top and 5 bottom boards), or reversible, with identical decks that can each carry the load.
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F
Fastener withdrawal characteristic
The fastener withdrawal characteristic (FWC, written Cw in the Uniform Standard) is a multiplier that rates how much a nail's threads improve its resistance to pulling out. A plain-shank nail scores 1.0; the Uniform Standard sets minimums of 1.9 for reusable pallets and 1.5 for single-use pallets.
Floor stacking
Floor stacking is the support condition in which a pallet rests on a flat floor, often with other unit loads stacked on top of it. It gives the highest pallet ratings because the floor supports the whole bottom: in a PDS example, 5,223 lb stacked one high, falling to 1,934 lb per pallet when stacked four high.
Flush
A flush pallet is one whose deckboard ends line up with the outside faces of the outer stringers or blocks, so nothing overhangs. It is the default construction for GMA-style 48x40 stringer pallets and most block pallets; the opposite is a winged pallet.
Fork tine
A fork tine is one of the steel arms on a forklift that slide into a pallet's fork openings to lift it. Tine width, spacing and length decide which openings a pallet needs; a common example tine is 4 in wide and 42 in long (100 mm and 1,070 mm in metric).
Free span
Free span is the unsupported distance a pallet must bridge between its supports, such as the clear gap between two rack beams. A 48 in long pallet racked across its length typically has about a 44 in free span; the longer the span, the lower the pallet's capacity and the greater its deflection.
Full four-way entry
Full four-way entry means both forklifts and pallet jacks can enter a pallet from all four sides. It comes from block construction: block pallets with a perimeter base, a unidirectional base with no crosswise bottom boards, or a panel bottom with cutouts are full four-way.
G
GMA pallet
A GMA pallet is the 48 x 40 in (1219 x 1016 mm) wood stringer pallet based on the 1992 Grocery Manufacturers Association specification. It has three notched stringers (partial four-way entry), 7 top and 5 bottom deckboards with 5-1/2 in lead boards, stands about 4.75 in tall and uses about 13.5 board feet and 84 nails.
Green 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 green: a GMA-style 48x40 in green mixed hardwood weighs about 59 lb, versus about 37 lb once it dries to 12%.
H
Heat treatment
Heat treatment (HT) is the ISPM 15 phytosanitary treatment in which wood packaging is heated until its core reaches at least 56 °C (133 °F) for 30 continuous minutes. Treated pallets carry an ISPM 15 mark with the code HT and can be used for international shipments.
Helical nail
A helical nail (helically threaded or screw-shank nail) has spiral threads along its shank that make it rotate as it is driven, giving much higher withdrawal resistance than a smooth nail. It is the usual pallet nail for medium- and high-density hardwoods; a GMA-style 48x40 typically uses 2-1/4 in x 0.112 in helical nails.
I
IPPC
The IPPC (International Plant Protection Convention) is the international plant-health treaty whose standards include ISPM 15, the rule for treating and marking wood packaging such as pallets in international trade. Its wheat symbol appears on every ISPM 15 mark.
ISPM 15 mark
The ISPM 15 mark is the stamp that shows wood packaging has been treated to the international phytosanitary standard. It contains the IPPC wheat symbol, a two-letter country code, the producer or treatment-provider number, and the treatment code (HT, DH, MB or SF).
K
Kiln-dried lumber
Kiln-dried (KD) lumber is wood dried in a heated kiln to a target moisture content, commonly 19% (KD19), 15% or 12%. Kiln drying reduces weight, shrinkage and mold risk, but a KD stamp alone does not show ISPM 15 compliance; that needs an HT mark.
Knot
A knot is the remains of a branch embedded in a board, visible as a round or oval area of cross grain. The Uniform Standard limits sound knots to one half of the cross-section on reusable pallets and seven eighths on single-use pallets, with tighter limits for unsound knots and holes.
L
Lead board
A lead board (also called an end board) is the outermost deckboard at each end of a pallet's top or bottom deck. Because fork tines and handling impacts hit the pallet ends first, lead boards are usually wider than the interior boards: 5-1/2 in versus 3-1/2 in on a GMA-style 48x40.
Load overhang
Load overhang is when the product or cartons on a pallet extend beyond the pallet's edges. It leaves the overhanging carton walls without support, which reduces their stacking strength and exposes them to damage from forks, racks and neighboring loads. The opposite, underhang, leaves bare deck around the load.
LoadSync
LoadSync is a free desktop tool released by the NWPCA (now Woodpack Global) in 2013 that let pallet users record their requirements (load, storage, stacking and handling) rather than a design, and send them as a file to a PDS-licensed pallet manufacturer, who returned a read-only viewer file with the spec, drawings and analysis.
M
Maximum working load
Maximum working load is the largest payload a pallet is allowed to carry in a specific load and support configuration, as defined in ISO 8611-3. Unlike the nominal load, it reflects how the load sits on the pallet and how the pallet is supported, so one pallet has different maximum working loads for racking, forklift handling and floor stacking.
Methyl bromide
Methyl bromide (MB) is a fumigant gas approved under ISPM 15 for treating wood packaging, shown by the code MB on the mark. It is being phased out and some countries no longer accept it, so heat treatment (HT) is now the normal choice for export pallets.
MIBANT
MIBANT stands for Morgan Impact Bend Angle Nail Tester, the impact-bend test for pallet nails defined in ASTM F680. It reports a bend angle in degrees: the lower the angle, the stiffer the nail. Quality pallet nails typically test in the 20s and 30s.
Moisture content
Moisture content (MC) is the weight of water in wood expressed as a percentage of the wood's oven-dry weight. Pallet specs treat 19% or less as dry; freshly sawn green wood is above the fiber saturation point of about 28% and shrinks roughly 1% in size for every 5% of moisture it loses below that.
N
Nominal load
Nominal load is the load rating produced by the standard ISO 8611 test with rigid beams and applicators. It lets pallets be compared on equal terms, but it is not the payload the pallet can safely carry in a real load and support condition; that is the maximum working load.
Notch
A notch is a cutout in the lower edge of a stringer that lets fork tines enter a stringer pallet from the side, making it partial four-way. The Uniform Standard recommends an opening about 2 in high (including the bottom deck) and 9 in long, with radiused corners between 1/2 and 1-1/2 in.
O
Overall height
Overall height is the total height of a pallet from the bottom of its lowest part to the top of its top deck. For a stringer pallet it is top deck + stringer height + bottom deck: a GMA-style 48x40 is 0.625 + 3.5 + 0.625 = 4.75 in. The EPAL 1 Euro pallet is 144 mm.
Overhang
In pallet construction, overhang is the distance a deck extends beyond the outer stringers or stringerboards, forming a wing. It is recorded as a single dimension, with zero meaning a flush pallet. It is different from load overhang, where the product extends past the pallet edge.
P
Pallet Design System (PDS)
The Pallet Design System (PDS) is the wood pallet design and analysis software from Woodpack Global (formerly NWPCA). First released in 1984 and now at version 6.12, it produces spec sheets, drawings and safe-load, deflection and service-life analyses. It runs on Windows under an annual lease of $2,000 a year for members and $5,250 for non-members.
Pallet footprint
A pallet footprint is its length x width in plan view, with the length (the direction of the stringers or stringerboards) stated first. The 48x40 in (1219 x 1016 mm) footprint is the most common in North America, and 1200x800 mm (EUR) in Europe; ISO 6780 lists six standard footprints.
Pallet jack
A pallet jack (pallet truck) is a hand or powered truck whose forks slide under a pallet and lift it slightly using wheels in the fork tips. Because the wheels must drop to the floor inside the pallet, the bottom deck needs wheel openings, and chamfered bottom lead boards help the wheels roll over.
Panel deck
A panel deck is a pallet deck made from a sheet of plywood or OSB instead of individual deckboards, giving a smooth, solid surface. The Uniform Standard requires the panel's face grain to run perpendicular to the stringers and panel pieces to be at least 24 in wide.
Partial four-way entry
Partial four-way entry means forklift tines can enter a pallet from all four sides, but pallet jacks only from two opposite ends. Notched stringer pallets such as the GMA-style 48x40 are partial four-way, as are block pallets with overlapping bottom boards.
Perimeter base
A perimeter base is a block-pallet bottom deck made of boards running around all four edges, like a picture frame, leaving the middle of each bay open. It supports the pallet evenly in both directions and allows full four-way entry for forklifts and pallet jacks.
Plain-shank nail
A plain-shank nail is a smooth nail with no threads or rings. Its fastener withdrawal characteristic is 1.0, below the Uniform Standard minimums of 1.5 (single-use) and 1.9 (reusable), so pallets mainly use smooth nails where they are clinched, as in block-pallet deck mats.
Pooled pallet
A pooled pallet is owned by a pooling company (such as CHEP, PECO or iGPS) and rented to shippers, who pay per use or trip instead of buying pallets. North American pooled pallets are 48x40: CHEP and PECO use wood block pallets and iGPS uses plastic. Costco requires pooled block pallets and accepts purpose-built pallets only by exception.
R
Rack storage
Rack storage is the support condition where a pallet sits on two (or three) rack beams with nothing underneath, so the pallet itself must span the gap. It usually gives a pallet's lowest load rating: in a PDS example, the same 48x40 rated 1,558 lb racked across its length versus 5,223 lb on the floor.
Remanufactured pallet
A remanufactured pallet is built from recovered (recycled) pallet components, often disassembled and rebuilt to a new size or design. It is one of the manufacture classes in the pallet classification string, and for export it must be re-treated and re-marked to ISPM 15, with any old marks removed.
Reusable pallet
A reusable pallet (multiple-use or multi-trip) is designed to make many trips and be repaired along the way. The Uniform Standard sets higher lumber quality and fastener minimums for reusable pallets, including a nail withdrawal characteristic of at least 1.9 and a head-to-shank ratio of at least 2.25.
Reversible
A reversible pallet is a double-face pallet whose top and bottom decks are identical, so either face can carry the load. It appears in the classification string as Double-Face Reversible and uses more wood than a non-reversible design with a lighter bottom deck.
RFQ
An RFQ (request for quote) is the document a buyer sends to pallet suppliers asking them to price a pallet. A good pallet RFQ states the size, the load and how it is supported and handled, the quantity and annual volume, delivery details, and compliance needs such as ISPM 15 or a PDS report.
Runner
A runner is the long base member of a skid or single-face pallet, effectively a stringer that rests directly on the floor. On plastic pallets, runners are the continuous rails under the deck (often 3, 5 or 6) that make the pallet rackable and conveyor-friendly.
S
Safe working load
Safe working load (SWL) is the maximum load a pallet is rated to carry in a specific support condition, such as racked, on a forklift or floor-stacked, with a safety margin built in. It is not the breaking load, and one pallet can have very different SWLs: a PDS example 48x40 rated 1,558 lb racked across its length and 5,223 lb stacked one high on the floor.
Shiner
A shiner is a nail that misses the stringer or block it was meant to enter, so its shank or point shows on the side of the member or sticks out of the pallet. The Uniform Standard allows no shiners on exposed faces, because they give no holding strength and can damage product and hands.
Shook
Shook is lumber that has been cut to the finished sizes of pallet or box parts, such as deckboards, stringers and blocks, ready for assembly. Pallet mills cut shook from cants or rough lumber rather than buying standard dimension lumber.
Single-face
A single-face pallet has only a top deck: its stringers, runners or blocks rest directly on the floor with no bottom deck. A skid is the most common example. It uses less wood than a double-face pallet but gives less support for stacking and conveyors.
Single-use pallet
A single-use pallet (also called expendable, one-way or limited-use) is designed to make one trip before being discarded or recycled. The Uniform Standard allows lower lumber quality and lighter fastener minimums for single-use pallets, such as a minimum nail withdrawal characteristic of 1.5 against 1.9 for reusable pallets.
Skid
A skid is a pallet with no bottom deck: a top deck fastened across two or more runners (stringers) that sit directly on the floor. Skids are used for machinery, crate bases and loads that are moved by forklift or dragged and then stay put.
Slip sheet
A slip sheet is a thin sheet of corrugated, solid fiberboard or plastic placed under a unit load in place of a pallet, with one or more tabs that a push-pull forklift attachment grips. Slip sheets save weight and space, fitting about 12 to 15% more product in a container, but need special attachments.
Slope of grain
Slope of grain is the angle between the wood fibers and the long axis of a board, stated as a ratio such as 1 in 4 (the grain drifts 1 in across for every 4 in along). The Uniform Standard allows a maximum slope of grain of 1 in 4 in pallet parts, for both reusable and single-use pallets.
Solid deck
A solid deck is a pallet deck with no gaps between the deckboards, made either from boards butted edge to edge or from a single plywood or OSB panel. It is used for small cartons, bags, drums and loose items that would sag into or drop through a spaced deck.
Specific gravity
Specific gravity (G) is the density of wood relative to the density of water, a dimensionless number. It is the main wood property in pallet connection design: in the Uniform Standard's withdrawal equation, nail holding power scales with G raised to the 2.5 power.
Split
A split is a lengthwise separation of the wood fibers that runs through the piece. The Uniform Standard limits splits in deckboards to one third of the board length on reusable pallets (full length allowed on single-use), and limits horizontal splits in stringers to under 4 in or twice the stringer width.
Staple
A staple is a two-legged wire fastener driven with a pneumatic tool, used on some pallets instead of nails. Pallet staples come in round or rectangular wire (commonly 14 to 16 gauge), are often adhesive-coated, and under the Uniform Standard need a crown of at least 3/8 in that is not parallel to the grain.
Strap slot
A strap slot (banding notch) is a recess cut in the top of a stringer or under the top deck so that strapping or banding can pass beneath the deckboards and hold the load to the pallet. PDS has analyzed strap slots as part of the stringer since version 5.3.
Stretch wrap
Stretch wrap (stretch film) is a plastic film stretched around a loaded pallet so that its tension holds the cartons together and ties the load to the pallet. Pallet design tools such as PDS and LoadSync list it as a load stabilizer, alongside straps and corner protectors.
Stringer
A stringer is a continuous beam that runs the full length of a stringer pallet between the top and bottom decks, specified as width x height x length. A GMA-style 48x40 uses three 1-3/8 x 3-1/2 x 48 in hardwood stringers, notched for partial four-way entry.
Stringer class
Stringer class is one of the two pallet classes in the Uniform Standard and PDS: pallets whose decks are supported by continuous stringers running the full length. The GMA-style 48x40 is the best-known stringer-class pallet. The other class is block class.
Stringerboard
A stringerboard is a full-length board on a block pallet that sits between the deckboards and the blocks and ties the blocks together, specified as thickness x width x length. The EPAL 1 Euro pallet uses three 22 x 145 x 800 mm stringerboards.
T
Third-angle projection
Third-angle projection is the orthographic drawing convention used in the United States, in which each view is placed on the side of the object it shows: the top view above the front view and the right-side view to its right. Pallet drawings use it to lay out the top, bottom, side and end views.
Tier sheet
A tier sheet, also called a layer pad or tier pad, is a flat sheet of corrugated board or plastic placed between layers of product on a pallet. It spreads load across the layer below, stabilizes the stack and protects product from the deckboards; corrugated triple-wall pads are common on 40x48 loads.
Title block
A title block is the boxed area, usually in the lower-right corner of a technical drawing, that identifies the drawing: title, drawing number, revision, date, scale, units, projection and who prepared it. On a pallet drawing it ties the drawing to the customer, pallet ID and spec revision.
Top deck
The top deck is the load-carrying surface of a pallet: the top deckboards (or a plywood or OSB panel) fastened across the stringers or stringerboards. A GMA-style 48x40 top deck has 7 boards, 5/8 in thick, covering 28.5 in of the 48 in length with 3.25 in gaps.
Two-way entry
A two-way entry pallet accepts fork tines from two opposite ends only. An unnotched stringer pallet is the classic example: forks slide in between the stringers from either end, and the solid stringers block entry from the sides.
U
Unidirectional base
A unidirectional base is a block-pallet bottom deck whose boards all run parallel in one direction, with no crosswise bottom boards. It is a full four-way design: forklifts and pallet jacks can enter from every side, though the pallet is stiffer and better supported along the board direction.
Unit load
A unit load is a pallet together with the product, packaging and stabilizers (such as stretch wrap or straps) that are secured to it so they can be handled as a single item. Designing the pallet and the load together, called unit load design, can save material on both.
W
Wane
Wane is bark, or a lack of wood, along the edge or corner of a board where the log's rounded outer surface ran through the piece. The Uniform Standard limits wane separately for exposed deckboards, hidden deckboards and stringers or blocks, with looser limits for single-use pallets, and allows it on at most one third of components.
Wheel opening
A wheel opening (hand-jack opening) is a space in a pallet's bottom deck where the load wheels of a pallet jack can drop through to the floor. On a GMA-style 48x40 stringer pallet the openings are 9.5 in long, between each bottom lead board and the interior boards, lining up with the stringer notches.
Wing
A wing is the part of a pallet deck that overhangs beyond the outer stringers or stringerboards. On a single-wing pallet only the top deck overhangs; on a double-wing pallet both decks do. Wings are used for bar-sling lifting and for bagged goods such as cement and fertilizer.
Woodpack Global
Woodpack Global is the new name of the National Wooden Pallet & Container Association (NWPCA), the US trade association for the wood pallet and container industry. It publishes the Uniform Standard for Wood Pallets and owns the Pallet Design System (PDS) and Crate Design System (CDS) software.
More reference
- Pallet sizes
Standard pallet sizes with drawings: 48x40, 42x42, 48x48, EUR 1200x800 and more. Weight, board feet, nail count and parts list for each build.
- Pallet types
Every pallet type explained: stringer, block, skid, winged, double-face, euro, CP, heat-treated, plastic and more, with how each is built and when to use it.
- Industries
The pallet sizes, constructions and buyer requirements each industry uses, from grocery and beverage to chemical drums, automotive and export.
- Guides
How to design, specify and quote wood pallets: deck board spacing, nail schedules, load capacity, racking, weight, board feet, cost and RFQs.
- Standards
The standards behind wood pallet design: the Uniform Standard for Wood Pallets, ISPM-15, ISO 6780, ISO 8611, ASTM D1185, ANSI MH1, EPAL and GMA.
- Materials
Pallet lumber species, grades, moisture content and nails: density, weight per board foot, bending strength and which nail to use in which wood.