Key takeaways
- Four failure modes: tarpaulins, bare concrete, exterior walls, and stacks too high for too long.
- Outdoor storage under a tarpaulin is worse than open air, because it traps humidity against the board.
- The same accumulation can drop from 2A in November to 4A or reject by March without doing any work in between.
- Selling in November — the best supply month of the year — frequently beats storing over winter.
Every March we buy accumulations that were worth thirty per cent more in November. The boxes did no work in between. They sat somewhere, and where they sat did all the damage.
The four ways winter storage goes wrong
1 · Outside, under a tarpaulin
The worst option available, and the most common. A tarpaulin keeps rain off and traps humidity underneath, producing a small permanently damp microclimate around the board. Open-air storage is genuinely better, which is counterintuitive enough that people do not believe it until they have graded both.
2 · On the concrete
Slabs wick moisture continuously, particularly through winter temperature swings. The bottom course takes it up and, because the bottom edge is the structural part that matters most, that is exactly the wrong place to lose strength.
A pallet or slip sheet under every stack solves it entirely and costs nothing.
3 · Against an exterior wall
Condensation forms on the inside face of uninsulated exterior walls through winter. Boxes stacked flush against them get a damp stripe down one side that is invisible until you turn the stack round in spring.
Eighteen inches of clearance is enough.
4 · Too high, too long
Creep is cumulative. A stack of flattened bands nine high in November is fine; the same stack twelve high in February has permanent set in the bottom three bands, and those boxes will not square up properly again.
| Storage | November grade | March grade | Value change per box |
|---|---|---|---|
| Indoors, palletised, banded, 9 high | 2A | 2A | No change |
| Indoors, on concrete, unbanded | 2A | 3A | −$1.80 |
| Indoors, against exterior wall | 2A | 3A | −$1.80 |
| Outside, under tarpaulin | 2A | 4A or reject | −$3.20 or worse |
| Outside, open air, on pallets | 2A | 3A – 4A | −$2.10 |
What good storage looks like
- Flattened. It is the single biggest factor in how much space the accumulation takes and how well it keeps its shape.
- Banded in consistent lots, so nothing splays and counts stay verifiable.
- On pallets or slip sheets. Never on the slab.
- Under a roof, with eighteen inches off exterior walls.
- Nine bands maximum, and rotate if the accumulation will stand more than a quarter.
Or just sell them in November
This is the alternative worth considering. November is the best month of the year for used box supply — inbound is high, demand is moderate, and collection capacity is easy to schedule. An accumulation sold in November fetches close to the top of its range.
The same material sold in March, after a winter on a slab, prices a rung lower. If you have no use for the containers yourself, storing them over winter is a way of paying for floor space in order to reduce the value of your own inventory.
Questions