Two products sit at the center of most load securement conversations: corrugated void fillers and dunnage air bags. Both prevent load shift and protect freight from transit damage. And in most situations, they work best together.
What they are not is interchangeable. Using the wrong one for your gap size, load type, or shipping mode is one of the more common and preventable causes of freight claims. This guide gives you the decision framework to get it right.
When Should You Use Corrugated Void Fillers vs Airbags?
Use corrugated void fillers when you have consistent, measurable void gaps, flat load faces, and need rigid bracing that holds position under lateral movement. Products like our drop-down DIAMOND-CORR® fillers and large cell corrugated honeycomb are engineered to fill defined spaces and reduce migration of the cargo. They are the backbone of boxcar and intermodal load securement.
Use dunnage air bags when your gaps vary, load faces are uneven, or your shipment moves through high-vibration environments. Air bags are an approved load securement device across OTR, intermodal, and closed boxcar applications, not just a void filler. They conform to the space around them, apply stabilizing pressure across the load face, and are required for many closed boxcar and intermodal shipments by regulation or load plan specification.
For high-risk or high-value loads, most experienced shippers use both.
What Is Void Fill Packaging in Freight Shipping?
In freight shipping, a void is any open space between cargo units, walls, or load faces where movement can occur during transit. That movement is load shift, and load shift is what drives damage claims.
Void fill packaging refers to the products used to fill or brace those spaces. The goal: eliminate room for freight to move. The right product depends on the size of the gap, the shape of your load, the forces in play during transit, and the shipping mode.
Corrugated void fillers and dunnage air bags are the two most common options. They approach the problem from different angles, and understanding both is how you build a load plan that actually holds.
What Are Corrugated Void Fillers and What Do They Do Best?
Corrugated void fillers are rigid, structural inserts made from corrugated board. Available in formats like collapsible void fillers, drop-down DIAMOND-CORR® fillers, bulkheads, dunnage panels, paper honeycomb, and large cell corrugated honeycomb, they are sized to fill a defined space and hold their shape under load.
Where corrugated void fillers perform best:
- Consistent void gaps with measurable depth and width
- Need a reduction in lateral shifting
- Flat, even load faces that allow full surface contact
- Boxcar and intermodal shipping where gap geometry is predictable
- Applications requiring repeatable installation without inflation equipment
The tradeoff: corrugated void fillers require accurate gap measurement and cannot conform to irregular load surfaces. Oversized inserts can buckle; undersized ones leave room for shift.
What Are Dunnage Air Bags and What Do They Do Best?
Dunnage air bags, also called air bag dunnage or pneumatic dunnage bags, are inflatable bags placed into voids between freight and inflated to fill the space and apply stabilizing pressure.
They conform to the shape of whatever they sit between, and they carry a designation most shippers overlook: air bags are an approved securement device, required by load plan or regulation for many closed boxcar and intermodal shipments.
Where dunnage air bags perform best:
- Inconsistent or irregular voids where corrugated inserts cannot maintain full contact
- Uneven load faces
- Over-the-road freight with continuous vibration
- Ocean freight and moisture-exposed environments
- Closed boxcar and intermodal applications where they are a required securement component
The tradeoff: air bags require an inflator and pressure verification. They also provide less resistance to direct compressive impact than corrugated structures. A pressure check protocol matters because a bag must be inflated to the correct working pressure to adequately secure the cargo. It’s also important to choose the right dunnage air bag to properly secure each shipment.
Which Option Works Best by Shipping Mode (OTR, Intermodal, Boxcar, Ocean)?
Over-the-Road (OTR)
Vibration is the dominant force in long-haul trucking. Dunnage air bags handle continuous vibration well because they apply pressure across the load face dynamically. Corrugated void fillers work in OTR applications when gaps are consistent and flat, but air bags see wider use across over-the-road shipments for their adaptability.
Intermodal
Intermodal containers experience vibration, impact at transfer points, and stacking loads. Corrugated void fillers provide strong structural bracing for consistent gaps at primary load faces inside containers, and dunnage air bags are commonly required to fill secondary or variable spaces. The FMCSA cargo securement rules and the Association of American Railroads (AAR) standards govern intermodal requirements, and air bags often appear as a specified securement method within those load plans.
Boxcar
The Association of American Railroads (AAR) standards govern boxcar loading. Corrugated products that meet load specifications are widely used because boxcar gap geometry tends to be predictable and rigid bracing aligns with AAR requirements. Dunnage air bags are also required for most closed boxcar shipments as an approved securement device, often specified alongside corrugated bulk heads or large cell honeycomb in a complete load plan.
Ocean Freight
Ocean containers face long transit times, humidity, and stacking forces. Poly-woven dunnage air bags resist moisture far better than corrugated void fillers, making them the more reliable choice in wet environments where corrugated materials may degrade before the shipment arrives.
The Biggest Mistakes That Cause Load Shift and How to Avoid Them
Most transit damage is not random. These patterns show up consistently:
- Guessing the gap instead of measuring it. Corrugated void fillers need accurate gap dimensions. Undersized inserts leave room to move; oversized inserts can buckle or fail to seat properly.
- Using air bags in gaps that exceed their rated range. Air bags have maximum void sizes. Beyond that threshold, they cannot maintain adequate stabilizing pressure across the load face.
- Applying corrugated fillers to uneven load faces. If the load face is not flat, a rigid insert cannot maintain contact across the surface. That creates pressure points and gaps where shift still occurs.
- Skipping inflation pressure verification. A bag must be properly inflated to the recommended pressures for the bag and the application. A pressure check protocol matters.
- Treating void fill as the only load securement layer. Void fill solutions work best as part of a broader container blocking and bracing strategy.
Quick Checklist: Choose the Right Void Fill for Your Next Shipment
Answer these questions before you choose a product:
- What is the measured gap size? Is it consistent across the load?
- Is the load face flat and even, or irregular?
- What forces affect this transportation method: impact, vibration, or both?
- What is the shipping mode: OTR, intermodal, boxcar, or ocean?
- Will the shipment pass through moisture-exposed environments?
- Does your crew have inflation equipment on site?
- Is this a closed boxcar or intermodal shipment that requires air bags as a specified securement method?
- Is this a high-value or damage-sensitive load that warrants a documented load plan?
If you answered “inconsistent gaps,” “uneven load face,” “ocean freight,” or “required securement device” to any of the above, dunnage air bags belong in your load plan.
If you answered “measured gaps,” “flat load face,” and “boxcar or intermodal,” corrugated void fillers are the right foundation.
When Should You Use Both?
On complex shipments, using both products in the same load is standard practice. A common configuration pairs corrugated void fillers as the primary bracing between large load faces and the container wall, with dunnage air bags filling the spaces where corrugated inserts cannot conform.
This approach is especially common in intermodal containers with mixed pallet sizes and in boxcar loads where corrugated bulk heads handle the primary blocking but smaller void spaces remain between units. Air bags step in where the geometry gets irregular.
If your load involves multiple freight types, mixed pallet heights, or modality transfers, a load plan built around both products gives you more consistent protection across the full transit.
Talk to Our Load Securement Experts
Selecting void fill packaging gets complicated fast when you factor in gap size, modality, load face geometry, and compliance requirements. If your shipment has any of those variables in play, the fastest path to a reliable answer is a load plan review with experts. Send us your shipment specs and we will help you identify the right void fill solution for your application. You can also explore our full line of dunnage air bags to compare sizes, valve types, and pressure ratings.
Frequently Asked Questions
Are corrugated void fillers the same as blocking and bracing?
No, but there is overlap. Container blocking and bracing is a broader category that includes methods used to restrict cargo movement inside a container or trailer, including wood bracing, load bars, and strapping. Corrugated void fillers are one tool within that category.
When are airbags better than corrugated void fillers?
Air bags outperform corrugated void fillers when gaps are inconsistent, load faces are uneven, the shipping environment involves moisture, or the application requires a flexible securement method that conforms to irregular geometry. They also step in as a required securement device on many closed boxcar and intermodal shipments.
What void gap size is too large for airbags?
Most standard flat dunnage air bags are rated for voids up to 12 inches wide. Beyond that range, a square airbag may be applicable up to a 30” void space. For larger spaces, you may need multiple void fill panels in conjunction with airbags.
Can I use airbags with uneven load faces?
Because air bags inflate to fill the available space, they adapt to irregular surfaces better than corrugated inserts. However, very severe irregularities or sharp edges can create punctures, so you may want to add a protective dunnage panel or corrugated sheet between the bag and the load edge.
What should I use for intermodal containers?
For intermodal shipping protection, the answer depends on your specific void geometry and load type. Corrugated void fillers work well for consistent gaps at primary load faces. Dunnage air bags handle secondary voids, variable spaces, and are often required as a specified securement method. Many intermodal loads call for both. If you are shipping in mixed configurations or across multiple modes, a documented load plan is the most reliable way to specify the right combination.
What should I use for boxcar load securement?
Corrugated void fillers, including bulk heads and large cell corrugated honeycomb, are widely used for boxcar load securement because boxcar gaps are predictable and rigid bracing aligns with AAR load requirements. Dunnage air bags are also required for most closed boxcar shipments as an approved securement device, typically working in conjunction with corrugated products in a complete load plan.
When should I ask for a load plan?
Request a load plan when your shipment involves mixed freight types, variable pallet heights, high-value cargo, damage-sensitive products, or a new shipping method you have not tested before. A load plan documents the void fill specification, placement, and pressure requirements so your crew installs it the same way every time. It also creates a record that supports damage claims if something goes wrong in transit.
