Guide
Cold docks, warm plants and condensation
Boxes on an unheated dock in January are cold, brittle and about to sweat. The trouble starts when they come inside.
Gaylords on cold docks have two problems. Cold makes the board stiffer and more brittle, and condensation forms when a cold box moves into warm, humid air. Twin Cities temperatures average 15.6 F in January, so a box on an unheated dock or in a trailer spends months well below freezing, and each trip into a heated plant is a condensation event. AICC says that moving corrugated between temperature zones causes internal condensation or moisture migration that weakens the board.
| Place | What happens to the board | Stack Check plans |
|---|---|---|
| Heated warehouse | Dry, steady air | 100% of strength |
| Unheated dock | Damp, cold air and swings in temperature | 65% of strength |
| Trailer | Condensation inside a closed box and a rough ride | 60% of strength |
| Cooler | Humid air, near the 90% level that halves board strength | 55% of strength |
| Freezer | Brittle board and condensation when it thaws | 60% of strength |
| Covered outdoors | Humidity that can pass 85% to 90% | 50% of strength |
The route that does the damage
- A box sits on an unheated dock at well below freezing. The board is dry and brittle.
- A forklift brings it into a heated plant. The warm air meets cold board and water forms on and in it.
- The box dries slowly, or does not, and goes back out to the dock.
- Repeat through the winter. Each cycle adds moisture and takes strength.
A single trip does not ruin a box. A season of them can. A Grade A box that spent January on a dock is not a Grade A box in March.
What to do
- Store gaylords in heated areas above 55 F (AICC).
- Give cold boxes time to warm before opening or stacking them.
- Keep a rule for the dock: nothing loaded stands there past a set number of days.
- Use a liner for fines and a lid for drips.
- Rotate the stack so the oldest box is on top, not on the bottom.
| Box | Heated warehouse, 30 days | Unheated dock, 30 days | Unheated dock, 90 days |
|---|---|---|---|
| 3‑wall Grade A, 500 lb | Two high | Do not stack | Do not stack |
| 3‑wall Grade B, 500 lb | Two high | Do not stack | Do not stack |
| 4‑wall Grade B, 700 lb | Two high | Do not stack | Do not stack |
The Twin Cities also average 45.3 inches of snow a year, which is what ends up on a dock floor and in a trailer. See box compression strength, how high to stack and Stack Check.
Questions, answered
Do gaylord boxes get weaker in the cold?
Cold makes board stiffer and more brittle, and adhesives can lose effectiveness. The bigger risk is condensation when a cold box comes inside.
How long should cold boxes warm up?
Until they reach room temperature. We do not give a number of hours, because it depends on the stack and the room.
Sources and last reviewed
Facts on this page were last reviewed 2026-11-11.
- Climate of Minneapolis-Saint Paul (Wikipedia): Winter and summer temperature and snowfall averages for the metro, used for the cold-dock reasoning.
- AICC: strengthening corrugated against cold weather: Industry guidance on cold weather, condensation between temperature zones, and strength lost over 90 days under load.
- PaperIndex Academy: humidity and corrugated strength: How corrugated board loses compression strength as relative humidity climbs from 50% to 90%.