Dunnage is the material that stops your freight from moving inside the box it travels in — airbags, wood bracing, foam, kraft paper, corrugated inserts. It is the least glamorous line on any packing list and the one that decides whether a container arrives as cargo or as a claim.
What dunnage means
The word is old and nautical: sailors laid loose wood in a ship's hold to keep cargo up off the wet floor and wedged against the roll of the sea. The job has not changed, only the materials. Today dunnage is anything placed around, under or between goods to immobilise them, absorb shock, and keep them off surfaces they should not touch.
People sometimes confuse it with packaging. Packaging is what encloses the product — the carton, the polybag. Dunnage is what fills the space around that packaging so nothing shifts. A well-packed carton inside a half-empty container with no dunnage will still arrive damaged, because the carton was never the problem; the eighteen inches of free space beside it was.
The main types, and where each one earns its keep
- Inflatable dunnage bags. Paper or polywoven bladders inflated between pallet rows or against a container wall. The workhorse of ocean and truck freight — cheap, fast to place, and they fill voids no rigid material can. Sized by the gap they need to close.
- Wood blocking and bracing. Lumber nailed or wedged to stop movement outright. What heavy machinery, coils and anything on a skid gets. ⚠️ If it crosses a border, wood dunnage must be ISPM-15 heat-treated and stamped — untreated wood gets shipments refused at the port.
- Foam. Cut or moulded to the product's shape. Expensive per unit, unbeatable for fragile and high-value goods, and reusable in closed-loop shipping.
- Corrugated inserts and dividers. Cardboard partitions, layer pads, corner boards. Light, recyclable, and the standard answer inside cartons and on palletised layers.
- Kraft paper and void fill. Crumpled paper, honeycomb wrap, air pillows. Parcel-level dunnage for e-commerce cartons.
- Plastic and moulded trays. Reusable dunnage for parts and automotive — costly upfront, cheapest per trip in a repeating lane.
- Steel strapping and edge protection. Not void fill, but the same job: holding a load still and spreading the pressure a strap would otherwise cut with.
How much dunnage is enough
The test is physical, not aesthetic: a properly dunnaged load does not move when the equipment does. Push a pallet row by hand — if it rocks, the trailer will make it worse over three hundred miles of expansion joints. Ocean containers get the harshest ride of all: weeks of roll, pitch and temperature swing, with condensation that turns an unprotected floor into a wet one.
Common failures we see on the dock when a container comes open:
- Void space at the door, where the last row had nothing behind it.
- Heavy on top of light, with no load-bearing structure between them.
- Airbags placed against a carton face instead of a corner, so the bag crushes the box it was meant to save.
- Nothing under the bottom layer in a container that sweated.
The economics nobody runs
Dunnage costs a few dollars per pallet. A damaged pallet costs the goods, the freight both ways, the disposal, the replacement order and the customer's patience. Shippers who cut dunnage to save materials cost almost always discover the exchange rate on the wrong shipment — and cargo insurance tends to be unsympathetic when the packing was the cause.
It also interacts with cube. Dunnage takes space, so a load planned tight to the walls leaves no room to secure itself. Plan the securing material into the load, not after it — run the numbers with our pallet and container calculator before the container is stuffed, not while it is.
We handle dunnage on both ends daily at our Kent, WA warehouse: cutting it away when we devan an inbound container, and building it back in when freight goes out on LTL or in a custom crate. If a lane keeps generating damage claims, it is usually the dunnage — send us photos of how it arrives and we will tell you what is missing.
