Stone Transport Breakage Allowance: Turn Square Meters into Pieces First
There is no percentage you can multiply for stone transport breakage allowance. Convert net area into pieces, reserve by the piece, round up to whole pallets, then convert back. For 100 m² of 600×600, start from 278 pieces, round up to 7 pallets of 280, and one extra pallet makes 320 pieces, or 115.2 m².
Is there a standard percentage for stone transport breakage allowance?
Stone transport breakage has no percentage you can apply as it stands. Damage does not spread evenly over an area; it writes off whole pieces, and one broken 600×600 slab is 0.36 m² gone. Whether a chip counts as a loss is not a matter of millimetres but of which edge it sits on. A chip on a face edge stays visible after fixing, so the piece is scrap. A chip on a joint edge is covered by the joint or by the neighbouring slab, so the piece stays usable as long as the joint width is not affected. A chip on the back comes down to two things: whether it is deeper than the mortar bed, and whether it falls on a back-bolt position. The five acceptance tolerances are edge length, thickness, diagonal difference, flatness and squareness — chipping is not one of them, which is why it has to be written into the order: which edge, whether chipping is allowed, and how a chipped piece is replaced. The sequence is fixed too: area into pieces, reserve by the piece, back to square meters. The rate is the result of those three steps, never an input you multiply by.
Why does a smaller size need a bigger reserve for the same area?
Because breakage comes from impact, and impact depends on piece weight times drop height, not on total area. The same 100 m² is 278 pieces at 600×600 and 1,112 at 300×300: four times the pieces, four times as many corners that can be knocked, while the total edge length only doubles. Breakage follows the piece count, not the area. Lighter pieces are handled differently, since one man can pick one up and throw it, and the extra drop height cancels the weight advantage. At 81 kg/m², at the same drop, the 29.2 kg piece hits about four times as hard as the 7.3 kg one (29.16÷7.29＝4.0), but the light piece gets thrown far more often.
| Size | Area per piece | Pieces per 100 m² | Piece weight (30 mm) | Handling |
|---|---|---|---|---|
| 600×600 | 0.36 m² | 278 | 29.2 kg | two-man lift |
| 300×600 | 0.18 m² | 556 | 14.6 kg | one-man carry |
| 300×300 | 0.09 m² | 1,112 | 7.3 kg | one hand, easily tossed |
Can processing waste and transport breakage be merged into one number?
No. The two accounts happen in different places, belong to different people and are visible to different degrees. Processing waste happens inside the factory: it is calculated from the layout drawing, and you can see what was cut and what was left over, and recheck it. Transport breakage happens outside: loading, lifting, the sea voyage, discharge — you never see that process, so it can only be estimated piece by piece. Merged into one figure, both ends go blind. Keep them as two lines on the quotation: processing waste on the processing line, replacement reserve on the reorder line.
Where does damage actually happen?
Three places, none of them in the middle. First, the outermost pallet at the door end: it has a wall or a neighbouring pallet on each side, and cargo in front, only the face toward the container doors is open, and the doors plus the timber braces or straps are all that hold it. If the braces were not made solid, or the straps have gone slack, the whole pallet leans out through the doors when they are opened for unloading. Braking actually pins it against the pallet in front of it, so what the door end needs guarding against is outward movement, not forward movement. Second, the ends of long strips and thin pieces: nothing supports the overhang, so the end breaks first. Third, pallet against pallet: neighbours push into each other under braking and the edge of one bears on the face of the next. The slabs travel standing up, so each piece carries its own weight straight down its bottom edge to the pallet and the floor, so no piece is carried by the one beneath it, which is why the pieces in the middle are the safest. How the packing is actually built is set out in our article "Wooden crate or timber pallet: which arrives with less damage?"; one conclusion is enough here: reserve by position, not spread as a ratio over the whole order. Ask your supplier for one number only: how many pieces stand on the door-end pallet, and hold the reserve at that figure: one pallet, plus whatever rounding up to whole pallets already added. With solid braces you can hold back less; on a first order it is not worth saving.
How many extra pieces should I reserve? Give me a method I can run.
Three steps. ① Net quantity into pieces: net area ÷ area per piece, round up. ② Nail down the reorder unit: how many pieces per pallet, because replacements ship by the pallet, not by the piece. ③ Divide the piece count by pieces per pallet, round up to whole pallets, then add the door-end pallet — a part pallet still counts as a whole one, because replacements only move in full pallets. Worked example: 100 m² of 600×600×30. 100÷0.36＝277.8, so 278 pieces. Suppose this batch runs 40 pieces per pallet (an example only; ask your supplier for the real figure): 278÷40＝6.95, so 7 pallets, 280 pieces. One more pallet for the door end: 8 pallets＝320 pieces＝115.2 m². The reserve is 320 minus 278, 42 pieces, about 15% of 278 (42÷278) — a ratio from this calculation, not a breakage rate. At 60 pieces per pallet: 278÷60＝4.63, so 5 pallets, 300 pieces, plus one for the door end makes 6 pallets＝360 pieces≈129.6 m². The ratio moves as soon as the pallet load changes, so write "includes 1 pallet of replacement reserve" rather than "includes 15%".
What has to be written into the order?
Three sentences. One, the packing unit: pieces per pallet and how the pieces are stacked, because the count on the door-end pallet is the base of your reserve. Two, the replacement terms: same batch, same colour, minimum shipping quantity, who pays freight — a replacement that does not match the colour cannot be laid in. Three, piece counting on arrival: count against the packing list at the pickup point and put any shortage into the delivery receipt before you sign, because a verbal note does not count. On our side: 30 mm slabs, 100 m² minimum order, 5 days to dispatch, and Pink Hemp (G564／G4564) follows the same schedule. One last number: 346 m² is what a 20ft container holds when it is filled with 30 mm standard slabs stacked flat, and standing pieces or shaped pieces fall short of it.