Pallet glossary

Summary

Plain definitions of the terms used on pallet drawings, spec sheets, RFQs and in the warehouse: components, lumber, fasteners, load ratings, handling, shipping and compliance.

A

Actual dimensionComponents and construction: An actual dimension is the measured size of a pallet or component at manufacture. Pallet spec sheets state component sizes as actual dimensions, for example a 5/8 × 3-1/2 × 40 in deckboard.
Annularly threaded nailFasteners: An annularly threaded nail, or ring shank nail, has a series of rings rolled into its shank that lock into the wood fibers. It is generally recommended for low-density hardwoods and most softwoods.
Automated storageHandling and storage: Automated storage, often called AS/RS (automated storage and retrieval system), stores and retrieves pallets with stacker cranes, shuttles and conveyors instead of forklift drivers. It needs pallets with tight dimensional tolerances, low deflection (often 0.5 in, 13 mm, or less) and sound bottom decks.

B

BarkMaterials: 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.
BlockComponents and construction: A block is a rectangular, square or cylindrical spacer between the decks of a block pallet. Most block pallets have 9 blocks in a 3 × 3 grid, and the block height sets the fork entry height.
Block stackingHandling and storage: Block stacking is storing unit loads directly on top of one another on the warehouse floor, in rows and columns, with no racking. The bottom pallet and the packaging carry the whole stack, so static load and box compression strength limit the height.
Board footMaterials: A board foot is a unit of lumber volume equal to 144 cubic inches, a board 1 in thick, 12 in wide and 12 in long (about 0.00236 m³). Pallet board feet = thickness × width × length in inches ÷ 144, summed over every part.
Bottom deckComponents and construction: The bottom deck is the lower layer of deckboards (or a perimeter, runner or panel base) on a double-face pallet. It spreads the load onto the floor, rack or conveyor and stabilizes the stringers or blocks.
Bottom deck coverageComponents and construction: Bottom deck coverage is the percentage of a pallet's underside covered by bottom deckboards. A GMA-style 48 × 40 bottom deck covers about 45%, less than the top deck, to leave room for notches and pallet-jack wheels.

C

CantMaterials: 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.
Center blockComponents and construction: The center block is the middle block in the 3 × 3 grid of a nine-block pallet. It supports the middle of the deck and, on EPAL pallets, carries the producer, date and treatment marks.
ChamferComponents and construction: A chamfer is a bevel cut along the edge of a bottom deckboard, usually a lead board, so pallet-jack wheels can ride up and over it instead of hitting a square edge.
Clinched nailFasteners: A clinched nail is driven all the way through the parts it joins and has its protruding tip bent over flat. Block-pallet deck mats (deckboards plus stringerboards) are commonly assembled with clinched nails.
Closed loopCommercial and lifecycle: A closed loop is a supply chain in which pallets travel between a fixed set of sites and are returned to the owner for reuse, for example between a parts supplier and an assembly plant. Because the pallets come back, higher-cost custom, plastic or metal pallets can pay for themselves.
Column stackingLoading and shipping: Column stacking is a stacking pattern where every case sits directly on top of the case below, with corners and walls aligned through the full height of the load. It keeps the most compression strength but is less stable than interlocking.
Combo palletCommercial and lifecycle: A combo pallet is a wood pallet built from a mix of new and recycled components, commonly new stringers with reclaimed deckboards or the reverse. It sits between new and fully recycled pallets in cost and consistency.
Composite blockMaterials: 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.
Concentrated loadPerformance and engineering: A concentrated load is a load that bears on one or a few small areas of the pallet deck instead of spreading over it, such as drums, machinery feet or a coil. It usually gives a much lower safe load than the same weight spread evenly.
ConveyorHandling and storage: A pallet conveyor moves loaded pallets on driven rollers or chains instead of a forklift. The pallet's bottom deck is the running surface, so the orientation of bottom boards, flatness, deflection and condition decide whether it runs reliably.
Core palletCommercial and lifecycle: A core is a used pallet, usually a standard 48 × 40 in stringer pallet, that a pallet recycler buys or collects as raw material to sort, repair and resell. Cores that cannot be repaired are dismantled for parts or ground.
Corner blockComponents and construction: A corner block is one of the four blocks at the corners of a block pallet. Corner blocks take the most fork and pallet-jack impact, so the Uniform Standard requires more fasteners there than at interior blocks.
Corrugated fiberboardMaterials: 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.
CP palletStandards and compliance: CP pallets (chemical pallets) are a family of nine standardized wood block pallets, CP1 to CP9, developed for the European chemical and plastics industries. Each type has a defined size and construction for loads such as bagged polymer, drums and bulk containers.
CreepPerformance and engineering: Creep is the gradual increase in a pallet's deflection while a load stays on it over time. Wood creeps, and plastic creeps much more, especially when warm, so racked pallets sag more after days or weeks than when first loaded.
Cross-boardComponents and construction: A cross-board is a board that runs at right angles to the main deckboards of a pallet. The term is informal: it usually means a block pallet's stringerboard, or the center boards of a cruciform bottom deck.
Cube utilizationLoading and shipping: Cube utilization is the share of the available volume, in a pallet footprint up to its height limit, a trailer or a container, that is actually filled with product. It is usually expressed as a percentage.
Cut stockMaterials: 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.

D

Debarked lumberStandards and compliance: Debarked lumber is wood from which the bark has been removed. ISPM 15 requires all treated wood packaging to be made of debarked wood, allowing only small pieces of bark: under 3 cm wide of any length, or wider pieces with a surface area under 50 cm² each.
Deck coverageComponents and construction: Deck coverage is the percentage of a pallet deck's area that is covered by deckboards. A GMA-style 48 × 40 top deck covers about 59%; a solid deck covers 100%.
Deck spacingComponents and construction: Deck spacing is the gap between adjacent deckboards on a pallet deck. With the end boards flush, gap = (deck length − total board width) ÷ (boards − 1); a GMA-style 48 × 40 top deck has 3-1/4 in (83 mm) gaps.
DeckboardComponents and construction: A deckboard is a board in the top or bottom deck of a pallet that runs perpendicular to the stringers or stringerboards. It is specified by actual thickness × width × length, for example 5/8 × 3-1/2 × 40 in.
DeflectionPerformance and engineering: Deflection is the amount a pallet bends or sags under load, measured at the point of greatest movement. Racking limits are commonly about 2% of the span, and automated systems often require 0.5 in (13 mm) or less.
Dielectric heatingStandards and compliance: Dielectric heating (DH) is an ISPM 15 treatment that heats wood packaging with microwaves or radio waves until the entire profile of the wood, including its surface, reaches at least 60 °C for 1 continuous minute. Treated wood is marked with the code DH.
Dimension orderComponents and construction: Dimension order is the convention for stating pallet sizes. In North America the first number is the length, meaning the stringer or stringerboard length, then width, then height: a 48 × 40 pallet has 48 in stringers.
Double-faceComponents and construction: A double-face pallet has both a top deck and a bottom deck. It is either reversible (both decks identical and load-bearing) or non-reversible (the bottom deck has fewer or different boards).
Douglas-firMaterials: 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.
Drive-in rackHandling and storage: A drive-in rack is high-density racking where the forklift drives into a lane and places pallets many deep on continuous rails along each side. The pallet is supported only along two edges, so its capacity across the unsupported direction governs.
DurabilityPerformance and engineering: Durability is a pallet's ability to survive repeated handling, measured as the number of trips or handling cycles before it needs repair or is scrapped. It is driven by fastener quality, lead board width, member thickness and species density.
Dynamic loadPerformance and engineering: Dynamic load is the weight a pallet can safely carry while it is being moved, supported on forklift tines, a pallet jack or a conveyor. It sits between the static rating and the racking rating.

E

Edge protectorHandling and storage: An edge protector, or corner board, is an L-shaped strip of laminated paperboard, plastic or other material placed on the vertical or top edges of a unit load. It spreads strapping and stretch wrap pressure, protects case corners, and can add vertical stacking strength.
Entry heightComponents and construction: Entry height is the clear vertical height of a pallet's fork opening, from the floor or bottom deck to the underside of the top deck. On a 2-way stringer pallet it equals the stringer height, typically 3-1/2 in (89 mm).
EPALStandards and compliance: EPAL (European Pallet Association e.V.) is the organization that licenses manufacturers and repairers of EPAL Euro pallets and other EPAL load carriers and controls their quality. The EPAL 1 Euro pallet is a 1200 × 800 × 144 mm block pallet used in open pallet exchange across Europe.

F

Floor loadingLoading and shipping: Floor loading is shipping cases or bags stacked directly on the floor of a trailer or container, without pallets. It fits more product in the vehicle but must be loaded and unloaded by hand or with special equipment. The term is also used for the load a floor can bear per unit area.
FlushComponents and construction: Flush describes a pallet whose deckboards end even with the outside faces of the stringers or blocks, so no part of either deck overhangs. Most pallets are flush.
FootprintComponents and construction: A pallet's footprint is its plan size, length × width, such as 48 × 40 in (1219 × 1016 mm) or 1200 × 800 mm. It sets how many pallets fit in a trailer, container or rack bay.
Fork entryComponents and construction: Fork entry is the set of sides from which forklift tines or pallet-jack forks can enter a pallet. Pallets are classed as 2-way, partial 4-way or full 4-way entry.
Fork tinesHandling and storage: Fork tines are the two steel arms on a forklift or pallet jack that slide into a pallet's openings to lift it. Their width, thickness, length and spacing set the minimum size of the pallet's openings and affect its dynamic load rating.
ForkliftHandling and storage: A forklift is a powered industrial truck that lifts, carries and stacks loads on two steel fork tines inserted into a pallet's openings. Its rated capacity applies at a stated load center, commonly 24 in (610 mm) in the US and 500 mm in Europe.
Four-way entryComponents and construction: Four-way entry means a pallet can be entered from all four sides. Full four-way pallets, usually block pallets with a perimeter or cruciform base, take both forklifts and pallet jacks from every side.
Freight classLoading and shipping: Freight class is a rating from 50 to 500 in the National Motor Freight Classification (NMFC) that US LTL carriers use to price shipments. Since the NMFC's 2025 overhaul, many commodities are classed by density on a 13-level scale, where denser freight gets a lower, cheaper class.
Freight densityLoading and shipping: Freight density is the weight of a shipment divided by the volume it occupies, measured at its outside dimensions with the pallet included. In the US it is given in pounds per cubic foot (pcf) and is the main factor in most LTL freight classes.
FSMAStandards and compliance: FSMA is the US Food Safety Modernization Act of 2011. Under its Sanitary Transportation of Human and Animal Food rule (21 CFR Part 1, Subpart O), pallets are transportation equipment and must be designed and maintained so they are suitable and adequately cleanable, and do not make food unsafe.
FTLLoading and shipping: FTL (full truckload) is a shipment that uses a dedicated trailer from origin to destination, with no terminal handling. A 53 ft dry van takes 26 standard 48 × 40 in pallets loaded straight or 30 turned, single stacked, subject to the legal weight limit.

G

GalvanizingMaterials: Galvanizing is coating steel with zinc to protect it from corrosion. Steel pallets are often hot-dip galvanized after fabrication, and galvanized nails, staples and hinges are used where wood pallets or collars see moisture.
GMAStandards and compliance: GMA stands for the Grocery Manufacturers Association (now the Consumer Brands Association), whose name became attached to the standard 48 × 40 in (1219 × 1016 mm) US grocery pallet: a partial four-way wood stringer pallet with three notched stringers, seven top and five bottom deckboards.
Grade A palletCommercial and lifecycle: A grade A (#1) pallet is a used pallet, usually a 48 × 40 in GMA-style stringer pallet, in the best common condition grade: sound, with few or no visible repairs and no repaired stringers. There is no single standard definition, so each supplier's grade rules apply.
Grade B palletCommercial and lifecycle: A grade B (#2) pallet is a used pallet, usually a 48 × 40 in GMA-style stringer pallet, that has been repaired more than a grade A: it may have companion stringers, metal plates or replaced deckboards. It is functional but less uniform, and definitions vary by supplier.
Green lumberMaterials: 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 from green lumber because drying adds cost.
GS1Standards and compliance: GS1 is a global, not-for-profit standards organization that issues company prefixes and maintains the identification and barcode standards used in supply chains, including GTINs for products, the SSCC for logistics units such as pallets, and the GS1-128 barcode.

H

HardwoodMaterials: Hardwood is lumber from broadleaf (deciduous) trees such as oak, maple, ash and yellow poplar. Most eastern US pallets are built from mixed hardwood cut stock, which is dense, strong and holds nails well.
HDPEMaterials: HDPE (high-density polyethylene) is the most common resin for plastic pallets. It stays tough at low temperatures, which suits freezers and cold chains, but it is less stiff than polypropylene, which matters for rack deflection.
Heat treatmentStandards and compliance: Heat treatment (HT) is the ISPM 15 method of heating wood packaging until the whole profile of the wood, including its core, reaches at least 56 °C for 30 continuous minutes. Treated pallets carry the IPPC mark with the code HT.
Helically threaded nailFasteners: A helically threaded nail has spiral flutes rolled into its shank so it rotates as it is driven, which locks it into the wood. It is the most common pallet nail, recommended for medium- and high-density hardwoods.
Honeycomb paperboardMaterials: Honeycomb paperboard is a panel made of kraft paper formed into hexagonal cells and faced with paper liners on both sides. It is light and stiff in compression, and it is used for paper pallet decks and feet.

I

Injection moldingMaterials: Injection molding forces molten plastic into a closed steel mold under high pressure. It produces most catalog plastic pallets with tight dimensions and fast cycles, but a new pallet mold only pays off at very high volumes.
Interior deckboardComponents and construction: An interior deckboard is any deckboard between the two lead boards of a pallet deck. On North American pallets it is usually 3-1/2 to 4 in (89 to 102 mm) wide, narrower than the lead boards.
Interlocking stackingLoading and shipping: Interlocking stacking is a stacking pattern where alternate layers are rotated or shifted so each case bridges the joints between cases in the layer below, like bricks in a wall. It ties the load together but reduces compression strength compared with column stacking.
IPPC markStandards and compliance: The IPPC mark is the stamp that shows wood packaging was treated under ISPM 15. It contains the IPPC symbol, a two-letter ISO country code, a producer or treatment provider code assigned by the national plant protection organization, and a treatment code (HT, DH, MB or SF), inside a border.
ISO palletStandards and compliance: An ISO pallet is a pallet built to one of the six footprints recognized in ISO 6780: 1200 × 800, 1200 × 1000, 1219 × 1016 (48 × 40 in), 1165 × 1165, 1067 × 1067 and 1100 × 1100 mm. ISO 6780 sets principal dimensions and tolerances, not construction.
ISPM 15Standards and compliance: ISPM 15 is the International Plant Protection Convention (IPPC) standard for wood packaging material in international trade. It requires pallets, crates and dunnage made of solid wood to be debarked, treated by an approved method such as heat treatment (56 °C core for 30 minutes), and marked with the IPPC mark.

J

JointComponents and construction: 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.

K

KD-HTStandards and compliance: KD-HT indicates wood that is both kiln dried (KD), dried to a target moisture content, and heat treated (HT) to ISPM 15. Only HT is an ISPM 15 treatment code; KD describes moisture and does not by itself make a pallet export compliant.
Kiln-driedMaterials: Kiln-dried (KD) lumber has been dried in a heated kiln to a target moisture content, most often 19% or less (KD19). Kiln drying reduces weight, shrinkage and mold risk, but a KD stamp alone does not show ISPM 15 compliance.
KnotMaterials: 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.

L

Lead boardComponents and construction: A lead board is the outermost deckboard at each end of a pallet's top or bottom deck, where forks enter. It is usually wider than the interior deckboards, typically 5-1/2 to 6 in (140 to 152 mm).
Leader board gapComponents and construction: The leader board gap is the space between a lead board (the outermost deckboard) and the next deckboard inward. On a bottom deck it is often wider than the other gaps to clear stringer notches and let pallet-jack wheels reach the floor.
Load barLoading and shipping: A load bar is an adjustable steel or aluminum bar fixed across the inside of a trailer or container, either wedged between the walls or locked into wall track, to keep pallets from sliding during transit. Horizontal decking beams also let a second tier of pallets be carried.
Load bridgingPerformance and engineering: Load bridging is the effect of a stiff unit load spanning across the pallet's weak points, so the packaged product carries part of the load and the pallet deflects and stresses less than it would under a flexible load of the same weight.
Load capacityPerformance and engineering: Load capacity is the maximum weight a pallet can safely carry under a stated support condition. It is always quoted per condition: static (on the floor), dynamic (on forks or a pallet jack) and racking (spanning rack beams), and the racking figure is usually the lowest.
Load overhangLoading and shipping: Load overhang is any part of a unit load that extends beyond the edges of the pallet's top deck. Unsupported case edges lose compression strength, get damaged in handling, and increase the measured size of the shipment.
LTLLoading and shipping: LTL (less-than-truckload) is freight too small to fill a trailer, shipped alongside other shippers' loads and moved through carrier terminals. It is priced by weight, distance, freight class and accessorial services, so pallet size and density affect the cost.
Lumber gradeMaterials: 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.

M

Methyl bromideStandards and compliance: Methyl bromide (MB) is a fumigant gas approved under ISPM 15 for treating wood packaging, marked with the code MB. It depletes the ozone layer, ISPM 15 encourages alternatives, and the EU has prohibited its use since March 2010 except in emergencies.
MIBANTFasteners: MIBANT (Morgan Impact Bend Angle Nail Tester) is an impact-bend test for nail stiffness, run under ASTM F680. A weight strikes a clamped nail and the resulting bend angle is recorded; a lower angle means a stiffer, better nail.
Mixed hardwoodMaterials: Mixed hardwood is pallet lumber made from several hardwood species that are not sorted by species, sold and specified as one mix. Spec sheets state it as percentages of density classes, such as 50% high, 25% medium and 25% low density.
Moisture contentMaterials: Moisture content (MC) is the weight of water in wood expressed as a percentage of the wood's oven-dry weight. Pallet specs usually call for 19% or less when dry wood is needed; green lumber is above about 28%.
Molded fiberMaterials: Molded fiber, in pallets, means wood fiber mixed with resin and pressed under heat into a one-piece shape. Presswood pallets made this way are light, nestable and exempt from ISPM 15, but they are not meant for open-beam racking.
MOQCommercial and lifecycle: MOQ (minimum order quantity) is the smallest quantity a supplier will produce or sell in one order. For pallets it depends on the material and process: wood pallets need little setup, while custom molded plastic pallets need a mold and very large runs.

N

NailFasteners: A nail is the standard fastener for wood pallets, driven through deckboards into stringers or blocks. Pallet nails are specified by shank type (helical, annular or plain), length, wire diameter, head diameter and bending strength.
Nail head diameterFasteners: Nail head diameter is the width of a nail's head. It sets how well the nail resists pulling through the deckboard; the Uniform Standard requires the head to be at least 2.25 times the wire diameter for reusable pallets.
Nailing patternFasteners: A nailing pattern is the number and position of fasteners at each joint of a pallet. The Uniform Standard sets minimums by deckboard width: 2 fasteners per joint for boards up to 5-1/4 in wide and 3 for 5-1/4 to 7 in.
Nine-legComponents and construction: A nine-leg pallet stands on nine separate feet in a 3 × 3 grid with no bottom deck. Most nine-leg pallets are nestable plastic or presswood pallets that stack inside each other when empty.
Nominal dimensionComponents and construction: A nominal dimension is the named or trade size of a pallet or piece of lumber, such as a 48 × 40 pallet or a 2×4, rather than its measured size. Lumber nominal sizes are larger than actual: a 2×4 is 1-1/2 × 3-1/2 in.
Non-reversibleComponents and construction: A non-reversible pallet is a double-face pallet whose bottom deck differs from the top deck, usually with fewer or wider-spaced boards, so only the top face is meant to carry the load.
NotchComponents and construction: A notch is a cutout in the lower edge of a pallet stringer that lets forklift tines enter from the sides, making the pallet partial four-way. A typical 48 × 40 notch is 9 in long and 1-1/4 in deep, starting 6 in from each end.

O

OakMaterials: Oak is a dense eastern US hardwood, grouped as species class 21 (red and white oak) in the Uniform Standard and PDS. It makes strong, stiff pallet parts but is heavy, especially when green.
One-way palletCommercial and lifecycle: A one-way pallet is a pallet designed to make one trip and not come back, such as export pallets or shipments to customers who keep or discard the pallet. It is usually built lighter and from lower-grade material than a reusable pallet.
OpeningComponents and construction: An opening is the clear space between the decks and between stringers or blocks that fork tines or pallet-jack forks enter. It is described by its width and its height.
OSB and plywoodMaterials: Plywood (glued wood veneers) and OSB (oriented strand board, glued wood strands) are wood structural panels. On pallets they are used as solid panel decks, deck strips and laminated blocks, and as processed wood they are exempt from ISPM 15.
Overall heightComponents and construction: Overall height is the total height of an empty pallet, from the floor to the top of the top deck. A GMA-style 48 × 40 is 4-3/4 in (121 mm) and an EPAL 1 is 144 mm (5.7 in).

P

PalletComponents and construction: A pallet is a flat, portable platform, usually of wood, plastic, metal or paper, on which goods are assembled into a single unit load so they can be lifted, moved, stacked and stored by a forklift or pallet jack.
Pallet Design SystemStandards and compliance: The Pallet Design System (PDS) is proprietary wood pallet design and structural analysis software from Woodpack Global (formerly the National Wooden Pallet & Container Association, NWPCA). Licensed pallet manufacturers use it to produce specification sheets, drawings, safe load ratings and service-life estimates.
Pallet dispenserHandling and storage: A pallet dispenser is a machine that holds a stack of empty pallets and releases them one at a time, usually onto a conveyor feeding a palletizer. It needs pallets with consistent dimensions, flat decks and sound bottom boards.
Pallet exchangeCommercial and lifecycle: Pallet exchange is an arrangement where a receiver hands back an equal number of empty pallets of the same type and quality for the loaded pallets it receives, so the shipper does not lose pallets with each delivery.
Pallet flow rackHandling and storage: A pallet flow rack is gravity racking where pallets ride on slightly inclined roller lanes from the loading aisle to the picking aisle, giving first in, first out rotation. The pallet's bottom deck rides directly on the rollers.
Pallet inverterHandling and storage: A pallet inverter is a machine that clamps a unit load and rotates it, often through 180 degrees, so the pallet underneath can be removed and replaced without restacking the product by hand.
Pallet jackHandling and storage: A pallet jack is a manual or powered truck with two low forks that slide into a pallet and raise it a few inches off the floor so it can be moved. Its load wheels drop through openings in the bottom deck, so it can only enter sides where those openings exist.
Pallet poolingCommercial and lifecycle: Pallet pooling is a rental system in which a pool operator owns the pallets, issues them to shippers, collects them from receivers, and inspects and repairs them for reuse. Shippers pay fees per pallet instead of buying pallets.
Pallet positionLoading and shipping: A pallet position is the space for one pallet: a floor spot in a trailer or container, or a slot in a warehouse rack. Carriers and third-party logistics providers (3PLs) often count capacity and charge storage by pallet position.
Pallet rackingHandling and storage: Pallet racking is a steel storage structure of upright frames and horizontal beams that holds loaded pallets in levels above the floor. The pallet usually spans the gap between two beams, so its racking load rating, not its floor rating, governs.
Pallet tripPerformance and engineering: A pallet trip is one complete cycle of use: the pallet is loaded, moved through the supply chain, unloaded, and made available for its next load. Durability and cost per use are both measured in trips.
Panel deckComponents and construction: A panel deck is a pallet deck made from a wood structural panel, usually plywood or OSB, instead of individual deckboards. It gives a solid, flat surface for small or unstable loads.
Partial four-wayComponents and construction: Partial four-way means forklifts can enter a pallet from all four sides but pallet jacks only from two. It is usually made by cutting notches in the stringers, as on the GMA 48 × 40 pallet.
Perimeter baseComponents and construction: A perimeter base is a block-pallet bottom deck made of boards running around all four edges, like a picture frame, which gives full four-way entry for forklifts and pallet jacks.
Phytosanitary certificateStandards and compliance: A phytosanitary certificate is an official document issued by the exporting country's national plant protection organization stating that a consignment of plants or plant products meets the importing country's plant health requirements. ISPM 15-marked wood packaging does not need one; the mark takes its place.
PinwheelingLoading and shipping: Pinwheeling has two meanings. In palletizing it is a pattern where cases are arranged in rotated groups around the center of each layer, often leaving a small void. In trailer loading it means turning some pallets 90 degrees so more fit on the floor.
Plain shank nailFasteners: A plain shank nail has a smooth shank with no threads. It has the lowest withdrawal resistance of pallet nails, so on pallets it is mainly used where it is clinched, such as block-pallet deck mats.
Plastic lumberMaterials: Plastic lumber is solid or hollow plastic profiles, usually extruded HDPE or rigid PVC and often recycled, cut and fastened like wood boards. Pallets built from it can be made to any size without a mold.
PolypropyleneMaterials: Polypropylene (PP) is a plastic resin used for plastic pallets. It is stiffer than HDPE at room temperature, which helps rack performance, but homopolymer PP becomes brittle in the cold, so freezer pallets use PP copolymer.
PoplarMaterials: Poplar is a lower-density hardwood common in pallet stock. The name covers two groups: yellow poplar (tulip tree, PDS class 29) and the true poplars such as aspen and cottonwood (low-density class 7).
Push-back rackHandling and storage: A push-back rack stores pallets several deep on nested wheeled carts that roll on slightly inclined rails. Loading a new pallet pushes the others back, and removing the front pallet lets the rest roll forward, so stock is last in, first out.
Push-pull attachmentHandling and storage: A push-pull attachment is a forklift attachment that grips the tab (lip) of a slip sheet, pulls the load onto wide platens, and pushes it off at the destination. It lets unit loads be handled on slip sheets instead of pallets.

R

Rack beamHandling and storage: A rack beam is the horizontal steel member that spans between upright frames in pallet racking and carries the pallets. The distance between the front and rear beams sets the pallet's unsupported span.
Racked across lengthPerformance and engineering: Racked across length is a support condition where the rack beams support the pallet's two ends and the pallet's length spans the open gap. On a stringer pallet the stringers carry the load across the span.
Racked across widthPerformance and engineering: Racked across width is a support condition where the rack beams support the pallet's two long sides and the pallet's width spans the open gap. On a stringer pallet the deckboards, not the stringers, carry the load across the span.
Racking loadPerformance and engineering: Racking load is the weight a pallet can safely carry while it spans the gap between rack beams with no support underneath. It is usually the lowest of a pallet's ratings and depends on the span, the direction racked and the number of beams.
Radiata pineMaterials: Radiata pine (Pinus radiata) is a fast-growing plantation softwood grown mainly in Chile, New Zealand and Australia. It is a common pallet species in those countries and is exported as pallet cut stock.
Recycled palletCommercial and lifecycle: A recycled pallet is a used pallet that has been collected, sorted, repaired if needed and put back into service, or a pallet rebuilt from reclaimed components. In the US it is usually a 48 × 40 in GMA-style stringer pallet sold by grade, such as grade A or grade B.
Remanufactured palletCommercial and lifecycle: A remanufactured pallet is a pallet assembled from components reclaimed from dismantled used pallets, sometimes to a different size or design from the originals. Under ISPM 15, a pallet with more than about one third of its components replaced counts as remanufactured and must be re-treated and re-marked.
Returnable palletCommercial and lifecycle: A returnable pallet is a pallet designed to make many trips and be sent back to its owner after each one, as in a closed loop between a supplier and a plant. It is built for durability, often from higher-grade wood, plastic or metal, and judged on cost per trip.
ReversibleComponents and construction: A reversible pallet is a double-face pallet whose top and bottom decks are identical, so either face can carry the load.
RFQCommercial and lifecycle: An RFQ (request for quote) is a buyer's request asking suppliers to price a defined product at stated quantities and terms. For pallets, a complete RFQ includes the pallet specification or requirements, volumes, delivery, compliance needs and quality rules.
Rotational moldingMaterials: Rotational molding (rotomolding) makes hollow, one-piece plastic parts by rotating a heated mold filled with powdered resin. Rotomolded pallets are thick-walled and durable, with cheap tooling but slow cycles and a high piece price.
RunnerComponents and construction: A runner is a continuous member along the bottom of a pallet or skid that rests on the floor. On skids it is the heavy stringer; on block and plastic pallets it is a bottom board or rail joining the blocks or feet in one direction.

S

Safe loadPerformance and engineering: Safe load (safe working load, SWL) is the largest load a pallet should carry in a given support condition, set well below the load that breaks it. Test standards divide the ultimate load by a safety factor, and PDS uses reliability-based safety levels.
Safety factorPerformance and engineering: A safety factor is the ratio between the load that causes a pallet to fail and the safe load it is rated for. ISO 8611 divides the ultimate load by 2 and ASTM D1185 by 2.84, before deflection checks; PDS uses reliability-based safety levels instead of a single factor.
ScrewFasteners: A screw is a threaded fastener turned into the wood rather than driven. On pallets, deck screws, lag screws and washer-head self-drilling screws are used for heavy skids, plastic lumber pallets and designs that must be taken apart or repaired.
Selective rackHandling and storage: Selective rack is the most common pallet racking: one pallet deep from each aisle, so any pallet can be picked without moving another. The pallet rests on a front and rear beam and spans the gap between them.
Single-faceComponents and construction: A single-face pallet has only one deck, the top deck, fastened to stringers or blocks, with no bottom deckboards. A skid is a single-face pallet.
SoftwoodMaterials: Softwood is lumber from coniferous trees such as pine, spruce and fir. Softwood pallets are lighter and more uniform than hardwood pallets, and they are the norm in Europe and much of the western and southern US.
Southern yellow pineMaterials: Southern yellow pine (SYP) is a group of pine species from the southeastern US (mainly loblolly, longleaf, shortleaf and slash pine). It is one of the densest and strongest softwoods used for pallets.
Spec sheetCommercial and lifecycle: A pallet spec sheet is a document that defines a pallet design completely: overall size and classification, every component's count and dimensions, lumber species and grade, fasteners, treatments and, when an analysis was run, load ratings by support condition.
SPFMaterials: SPF (spruce-pine-fir) is a group of light-colored, low-density softwood species sold together as one lumber group, mainly from Canada and the northern US. It is light, easy to nail and common in softwood pallets.
SplitMaterials: 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.
SSCCStandards and compliance: The SSCC (Serial Shipping Container Code) is an 18-digit GS1 identification number that uniquely identifies one logistics unit, such as a loaded pallet. It is encoded in a GS1-128 barcode on the pallet label with Application Identifier (00) and linked to the shipment's advance ship notice.
Stacking patternLoading and shipping: A stacking pattern is the arrangement of cases on a pallet: how they are placed within each layer and how each layer relates to the one below. The main choices are column stacking, which maximizes box strength, and interlocking patterns, which improve stability.
StapleFasteners: A staple is a two-legged wire fastener joined by a crown, driven by a pneumatic tool. Some pallets are stapled instead of nailed, often with adhesive-coated staples of round or rectangular wire.
Static loadPerformance and engineering: Static load is the weight a pallet can safely carry while sitting stationary on a flat, solid floor, including the load from unit loads stacked on top of it. It is the highest of a pallet's ratings because the floor supports the whole bottom deck.
StiffnessPerformance and engineering: Stiffness is a pallet's resistance to bending under load, the inverse of how much it deflects. It depends mostly on the depth of the stringers or deckboards, the material's modulus of elasticity, moisture content and temperature.
StrappingHandling and storage: Strapping, also called banding, is a steel or plastic band tensioned and sealed around a load, often through or around the pallet, to hold heavy or rigid items together and to the pallet. The main materials are steel, polyester (PET) and polypropylene (PP).
Stretch wrapHandling and storage: Stretch wrap is a thin, elastic plastic film, usually linear low-density polyethylene, wound tightly around a unit load under tension. It holds the cases together and to the pallet so the load stays stable in handling and transit.
StringerComponents and construction: A stringer is the continuous beam that runs the full length of a stringer pallet between the top and bottom decks. Most 48 × 40 pallets use 3 stringers about 1-1/4 to 1-1/2 in wide and 3-1/2 in (89 mm) tall.
StringerboardComponents and construction: A stringerboard is a continuous board on a block pallet that runs the full pallet length between the deckboards and the blocks, tying the blocks together. EPAL 1 uses three stringerboards of 22 × 145 × 800 mm.
Structural foam moldingMaterials: Structural foam molding is a low-pressure injection process in which a gas or blowing agent foams the plastic core while a solid skin forms against the mold. It makes thick, rigid, heavy-duty plastic pallets.
Support conditionPerformance and engineering: A support condition is the way a loaded pallet is held up: on the floor, in a floor stack, on forklift tines, on a pallet jack, across rack beams, on a shelf or on a conveyor. Every pallet load rating applies to one named support condition.

T

ThermoformingMaterials: Thermoforming heats a plastic sheet and pulls it over a mold with vacuum or pressure. Single-sheet thermoformed pallets are light and nestable; twin-sheet pallets fuse two formed sheets into a stiffer, hollow structure.
Thread angleFasteners: Thread angle is the angle of the spiral flutes on a helically threaded nail. Pallet nails typically have thread angles of about 57 to 69°, and together with the flute count and thread diameter it sets how many turns the thread makes.
Ti-hiLoading and shipping: Ti-hi describes how cases are stacked on a pallet: the ti is the number of cases in each layer and the hi is the number of layers. Ti times hi gives the cases per pallet; for example, a 10 × 5 ti-hi is 50 cases.
Tier sheetHandling and storage: A tier sheet (layer pad) is a flat sheet of corrugated board, solid fiber or plastic placed between layers of a unit load, or on the pallet deck, to spread weight, bridge deck gaps and stabilize the layers. It is not lifted by equipment.
Top deckComponents and construction: The top deck is the load-carrying upper surface of a pallet, made of deckboards or a panel fastened across the stringers, stringerboards or blocks.
Two-way entryComponents and construction: Two-way entry means forks and pallet jacks can enter a pallet from two opposite ends only. Unnotched stringer pallets and most skids are two-way.

U

UL 2335Standards and compliance: UL 2335 is the UL standard for fire tests of storage pallets. Plastic pallets listed to UL 2335, or approved to FM 4996, can be treated as equivalent to wood pallets when fire codes set sprinkler protection, while unlisted plastic pallets can raise the required protection.
UnderhangLoading and shipping: Underhang is when the unit load's footprint is smaller than the pallet's top deck, leaving part of the deck uncovered around the edges. It wastes cube and can leave the load less stable, but it keeps case walls fully supported.
Uniform StandardStandards and compliance: The Uniform Standard for Wood Pallets is the North American wood pallet industry standard published by Woodpack Global (formerly NWPCA). It defines pallet terminology and classifications and sets requirements for lumber quality, dimensional tolerances, fasteners, assembly, repair, remanufacture and performance.
Uniformly distributed loadPerformance and engineering: A uniformly distributed load (UDL) is a load whose weight is spread evenly over the full top deck of the pallet. Most published pallet ratings assume a UDL unless they say otherwise.
Unit loadPerformance and engineering: A unit load is a group of items, usually cases on a pallet or slip sheet, secured together so it can be stored and moved as a single unit by a forklift or pallet jack. It includes the pallet, the packaging, the stacking pattern and the stabilizers.

W

WaneMaterials: Wane is bark, or the absence of wood, on the edge or corner of a sawn piece, where the cut reached the outside of the log. Pallet lumber grades limit how wide and deep it can be.
White woodCommercial and lifecycle: White wood (whitewood) is the pallet trade's name for generic, unpainted wood pallets, usually 48 × 40 in GMA-style stringer pallets, that users buy, own and trade, as opposed to painted pooled pallets. In lumber, whitewood also names a group of light-colored softwoods such as spruce and fir.
WingComponents and construction: A wing is the part of a pallet deck that overhangs the outer stringers or stringerboards. A single-wing pallet has only the top deck overhanging; a double-wing pallet has both decks overhanging.
Wire diameterFasteners: Wire diameter is the diameter of the steel wire a nail or staple is made from, measured on the shank before threads are rolled. Pallet nails are commonly 0.099 to 0.120 in (2.5 to 3.0 mm), or 12.5 to 11 gauge.