The two products - different jobs
Wood dunnage is sawn or laminated lumber (2x4, 2x6, 4x4, 4x6, 6x6, 8x8, 10x10) used to raise, separate, stabilize, and brace freight structurally. It carries compression and point-loads, distributes load across more deck area, and holds freight against trailer walls.
Dunnage airbags are inflatable polywoven or kraft-paper bags inflated with compressed air at the loading dock. They fill voids between palletized loads, preventing shift during transit by pneumatic pressure against the surrounding cargo.
The two solve different load-securement problems. Wood provides structural bracing - the beam that holds a steel coil down to the trailer deck. Airbags provide void-fill - the pneumatic cushion between two stacks of appliances that keeps them from banging into each other.
| Factor | Wood dunnage | Dunnage airbags |
|---|---|---|
| Point-load capacity | 5,000 - 100,000+ lb | 500 - 5,000 lb |
| Structural bracing | Primary function | Not viable |
| Void-fill between loads | Possible but wasteful | Primary function |
| Cost per linear foot (2x4) | $0.65 - $1.10 | N/A |
| Cost per airbag (small) | N/A | $3 - $8 |
| Cost per airbag (large) | N/A | $12 - $35 |
| Reusability | One-way typical | 5 - 30 cycles |
| Setup/takedown labor | Higher (nails + strap) | Lower (inflate + deflate) |
| AAR OTL rail-grade | Yes (standard) | No (not approved for rail) |
| ISPM-15 export | Required for wood | Not required for airbags |
When wood dunnage wins
For heavy point-load bracing. Steel coils (10,000-30,000 lb per coil), transformer bases, generator bases, heavy machinery - all require heavy-timber dunnage (6x6 or 8x8 Douglas fir) rated for the point-load. Airbags cannot carry structural compression at this scale.
For rail freight. AAR Open Top Loading Rules specify wood dunnage for every open-top rail load class. Airbags are not approved for rail OTL applications; wood is the required material.
For blocking against trailer walls. The 4x4 blocked against the nose of a trailer that stops a load from sliding forward under braking - this is structural wood dunnage, not an airbag.
For export breakbulk and heavy-lift ocean freight. Vessel transit forces require wood structural bracing; airbags are supplemental to wood for void-fill.
For engineered-drawing project cargo bracing. NASA, SpaceX, and DOT-approved heavy-lift drawings specify timber bracing with calculated point-load distribution - airbags are not an engineering-approved substitute for structural wood.
When airbags win
For void-fill between palletized loads. The gap between two 48x40 pallet stacks in a 102-inch trailer is 22 inches - fill it with a 24-inch airbag inflated to 2 psi and the pallets cannot shift. No wood required.
For truckload gap-filling where cargo distribution leaves spaces. Grocery truckload shipping (cases of various products) often has irregular voids that airbags fill faster than wood.
For high-volume outbound docks where loading speed matters. An airbag inflates in 30-60 seconds; wood takes 3-5 minutes to cut, nail, and strap. For 20 trailers per day the labor savings add up.
For reusable truckload operations. Standing lane programs where airbags return with the empty trailer can see 20-30 cycle reuse. Wood dunnage is typically one-way (cost of recovery exceeds material value).
The hybrid approach
Most high-volume shippers use both. Wood dunnage for structural bracing (blocks against nose and tail of trailer, timber under heavy point-loads, side blocking against trailer walls) and airbags for void-fill between palletized sections.
For an appliance truckload: wood 2x4 blocks against the nose and tail, wood 2x4 between layers of refrigerators, airbags filling the lateral voids between appliance stacks.
For a steel coil truckload: heavy-timber 6x6 bunks under each coil, side timber blocks against trailer walls, no airbags (airbags cannot handle coil-point-load pressure).
For a grocery truckload: minimal wood (occasional block against nose), heavy use of airbags filling voids between case stacks.
Industry recommendations
Steel + heavy manufacturing
Wood dominant - heavy timber bunks and bracing for coils and project cargo. Airbags supplemental for void-fill between loads.
Automotive OEM + supply
Both - wood block kits for structural bracing between palletized parts; airbags for void-fill in the trailer gaps.
Appliance manufacturing
Wood 2x4 between layers for compression, airbags for lateral void-fill between stacks.
Grocery + food distribution
Airbag-dominant - truckload void-fill between irregular case stacks. Wood used sparingly for nose/tail blocking only.
Rail freight (AAR OTL)
Wood exclusively. Airbags not approved for rail OTL applications.
Project cargo + heavy-lift export
Wood timber bracing per engineered drawing. Airbags supplemental void-fill at non-structural locations.
Chemical hazmat (49 CFR 173.136)
Wood for the regulated bracing (nose, tail, side blocks); airbags for void-fill between drum stacks.
The decision
Buy wood dunnage if: your cargo has heavy point-loads (steel, machinery, project cargo), you ship rail (AAR OTL requires wood), you need structural bracing against trailer walls, you ship export freight that needs ISPM-15 stamping, or your engineered drawing specifies timber. See our dunnage catalog for standard softwood, heavy timber, laminated blocks, and ISPM-15 export.
Buy airbags if: your primary need is void-fill between palletized loads, you have standing lane programs where airbags return with the empty trailer, your loading-dock speed is a bottleneck, or your cargo is lightweight-but-shifty (grocery, consumer goods).
In practice, run both. Most high-volume shippers use wood for structural bracing and airbags for void-fill in the same trailer.
Frequently asked questions
Can airbags replace all wood dunnage in a truckload?
No - airbags cannot carry structural point-loads or brace against trailer walls under braking force. Even in airbag-dominant truckloads (grocery, consumer goods), wood is used for nose/tail bracing. The two are complementary, not substitutes.
Do airbags work for rail freight?
No - AAR Open Top Loading Rules specify wood dunnage for all open-top rail freight. Airbags are not an approved OTL material. For intermodal container-on-flatcar shipping the airbag inside the container is approved for container-internal use, but structural rail bracing uses wood.
What is the cost difference per truckload - wood only vs airbags only?
For a 53-foot trailer of palletized grocery: wood-only approach costs $120-$180 in materials and 30-45 minutes of dock labor; airbag-only approach costs $35-$60 in airbags and 10-15 minutes of dock labor. For a steel coil truckload: airbag-only is not viable; wood timber bunks run $200-$400.
Can airbags be reused across multiple shipments?
Yes - airbag reuse is standard practice on standing lane programs with return economics. Typical cycle life 5-30 depending on handling and inflation pressure. Wood dunnage reuse is less common (one-way is typical).
Do airbags require ISPM-15 for international shipping?
No - airbags are not wood packaging and are not subject to ISPM-15. For international shipments where wood dunnage would need heat-treatment and IPPC stamping, airbags are a workaround for the specific securement function the wood was doing. However, structural bracing still requires wood with ISPM-15 stamping.
What is 49 CFR 173.136 and how does it affect dunnage choice?
49 CFR 173.136 is the DOT regulation requiring that non-bulk hazardous materials be braced inside the transport vehicle. The regulation specifies that bracing prevent horizontal cargo shift - which requires structural wood blocking, not airbags. Airbags can supplement wood for void-fill but cannot replace the regulated bracing.
How quickly can you deliver dunnage and airbags?
For wood dunnage: same-day in 19 Florida counties for standard sizes, 1-6 day national freight. For airbags: we partner with specialty airbag distributors; standard lead time 1-3 business days.
Can I quote a complete truckload securement package (wood plus airbags)?
Yes - send us the cargo type and lane, and we quote the complete package (wood block kit + recommended airbags) with per-shipment pricing.
Updated 2026-10-07