Bottom deck coverage (pallet)
Also called: bottom coverage, base coverage
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.
In depth: Pallet stacking patterns: column, interlock, pinwheel and brick
Bottom deck coverage uses the same formula as deck coverage: total bottom board width ÷ deck length. It matters for different reasons than top coverage, because the bottom deck bears on the floor, a rack, a conveyor or the load below.
Typical values
| Pallet | Bottom boards | Coverage |
|---|---|---|
| GMA-style 48 × 40 | 2 × 5.5 + 3 × 3.5 = 21.5 in over 48 in | 45% |
| EPAL 1 | 2 × 100 + 1 × 145 = 345 mm over 800 mm | 43% |
| Reversible pallet | Same as top | Same as top, often 60% or more |
| Single-face pallet | None | 0% (stringers only) |
Values are calculated from standard board sizes.
Why it matters
When loaded pallets are stacked, the bottom deck of the upper pallet presses on the load below. Low coverage and wide gaps concentrate that pressure on narrow strips, which crushes cartons in the lower unit load. Roller conveyors need bottom boards that span enough rollers in the direction of travel. More bottom coverage, though, blocks notches and leaves less room for pallet-jack wheels. PDS notes that in a stack, the second pallet up has the most stressed bottom deck.
On a spec sheet
Coverage follows from the bottom deck table and spacing rule. If you double-stack or use conveyors, state that in the handling requirements so the manufacturer can size the bottom deck.
Related
- GlossaryDeck coverage (pallet)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%.
- GlossaryBottom deck (pallet)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.
- GlossaryNon-reversible palletA 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.
- GuidesPallet stacking patterns: column, interlock, pinwheel and brickColumn stacking puts each box directly on the box below and keeps the most compression strength. Interlocking patterns (brick, pinwheel) rotate alternate layers so boxes overlap, which adds stability but can cut stacking strength sharply. Many loads use columns with tie sheets, or interlock only the top layers.
- GuidesPallets for automation: conveyors, AS/RS and robotic palletizersAutomated systems need consistent, flat, stiff pallets. Bottom boards must cross the conveyor supports (perpendicular to rollers, across chain strands), gaps must not snag, flatness is often held to 1/4 in or better, and AS/RS racks commonly limit sag to 0.5 in. Perimeter-base block and plastic pallets run either way.
More in Components and construction
- GlossaryActual dimension (pallet and lumber)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.
- GlossaryBlock (pallet)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.
- GlossaryCenter block (block pallet)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.
- GlossaryChamfer (pallet)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.
- GlossaryCorner block (block pallet)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.
- GlossaryCross-board (pallet)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.
Last reviewed 2026-09-24. 246 words.