By Luis Lopez, AI transportation consultant, CEO of Go Hub.io Holdings Corp and subsidiaries, and host of the Freight Guru Podcast
Dunnage is the material that keeps freight from moving. It fills empty space, braces loads against each other and the trailer walls, protects edges and keeps cargo off the floor. It rarely appears on a rate quote, and it is easy to treat as an afterthought. But when a load shifts, crushes or tips in transit, missing or wrong dunnage is often part of the reason.
What counts as dunnage
Dunnage covers any material used to fill voids and protect or secure cargo during shipping. The common types are:
- Dunnage bags (airbags). Inflatable bags placed in gaps between pallets or between the load and the trailer walls. Once inflated, they press against the cargo and hold it in place.
- Lumber blocking and bracing. Wood pieces cut and fastened to stop cargo from sliding forward, backward or sideways. Common in containers, on flatbeds and with heavy or irregular freight.
- Corrugated or honeycomb paperboard. Sheets, pads and void fillers made from paper products. Light, recyclable and useful for filling gaps or separating layers.
- Foam. Pads, blocks and sheets that cushion fragile items and absorb shock.
- Edge and corner boards. Protectors placed on the edges of pallets or cartons so straps and neighboring freight do not crush them.
- Load bars. Adjustable bars that span the trailer to hold freight back from the doors or keep partial loads from sliding.
- Friction mats. Mats placed under pallets or cargo to increase grip on the floor and reduce sliding.
When each type fits
As an AI transportation consultant, the first thing I look at in a damage pattern is the empty space in the trailer. Most dunnage choices come down to the size of the gap and the type of freight:
- Gaps between pallets in a van or container: dunnage bags sized for the void, or paperboard fillers for smaller spaces.
- Partial loads with open floor at the rear: load bars or straps to keep freight from sliding toward the doors. The tools for this are covered in dry van load bars, straps and airbags.
- Heavy, dense or irregular cargo in containers: lumber blocking and bracing built to hold the load in place. The method is explained in container blocking and bracing explained.
- Fragile items: foam and corner protection, plus careful separation from heavier freight.
- Smooth-bottom pallets on slick floors: friction mats to reduce sliding.
- Stacked or strapped cartons: edge boards so straps do not cut into the packaging.
Dunnage works alongside good pallet building. Freight that is poorly wrapped or overhanging the pallet will not be saved by dunnage around it. Pallet wrapping is covered in stretch wrap for pallets explained.
Dunnage bags: match the bag to the void
Dunnage bags are effective but easy to misuse. The bag’s size and inflation pressure must match the void, following the manufacturer’s instructions. A bag that is too small for the gap may not hold the load. A bag over-inflated can push against cartons hard enough to crush them, or burst. Bags should press against flat, solid faces, not against sharp edges or loose cartons that can be punctured or deformed. And they should never be placed against the trailer doors, where they can make opening dangerous.
Who supplies dunnage and who removes it
In most shipments, the shipper or whoever loads the trailer supplies and installs dunnage, because they know the freight and control the loading. On some loads, a carrier may bring load bars or straps as standard equipment. On others, the rate confirmation or shipper’s instructions say who supplies what.
Removal is often less clear. When the trailer is unloaded, someone has to take out the dunnage and dispose of it. The receiver usually handles it as part of unloading, but disagreements come up when dunnage is left in the trailer and the next pickup finds it full of wood, bags and paper. To avoid confusion:
- State in the shipping instructions who supplies dunnage.
- Agree with the receiver who removes and disposes of it.
- Note on the rate confirmation if the carrier is expected to haul away any materials.
- Have the driver photograph the empty trailer after unloading if dunnage is left behind.
Disposal at the receiver
Receivers deal with dunnage every day. Wood blocking, inflated bags, paperboard and plastic all have to go somewhere. Some can be reused, some recycled and some go in the trash. Shippers who use excessive or hard-to-dispose dunnage may hear about it from receivers. Choosing materials that are easy to remove and recycle can make deliveries smoother.
ISPM 15 and wood dunnage on exports
For international shipments, solid wood dunnage is subject to ISPM 15, the international standard for wood packaging material. It requires solid wood used in packaging and dunnage to be treated and marked with the approved stamp. Untreated or unmarked wood can cause problems when the shipment reaches the destination country. Lumber blocking in an export container needs the same attention as wood pallets and crates. Before an export load is built, confirm that every piece of solid wood dunnage is treated and marked, and keep a record of the supplier.
Common dunnage mistakes
- Leaving gaps unfilled. Even small voids let freight build momentum when the truck brakes or turns.
- Wrong dunnage bag size or pressure. Too small does not hold; too much crushes.
- Blocking that is not fastened. Loose lumber can become a projectile in the trailer.
- Untreated wood on export loads. A shipment can be held up for wood that does not carry the right mark.
- No edge protection under straps. Straps cut into cartons and damage the freight they were meant to protect.
- Nobody agreed on removal. Leftover dunnage becomes a dispute at the next pickup.
For a broader look at why freight gets damaged, see the top causes of freight damage and how to prevent them.
The bottom line
Dunnage is cheap compared with a damage claim. Choosing the right type for the freight and the gap, installing it correctly and agreeing on who supplies and removes it prevents a large share of in-transit damage and the arguments that follow.
For more conversations on freight and AI, subscribe to the Freight Guru Podcast.
About the author: Luis Lopez is a Miami-based AI transportation consultant and logistics entrepreneur, the CEO of Go Hub.io Holdings Corp and subsidiaries, and host of the Freight Guru Podcast.