Dunnage, Corner Protectors, and Edge Guards: How To Protect a Flatbed Load

There's a quiet problem with hauling a load on an open flatbed: the straps and chains doing the holding can also do the damage. Cinch a strap over the sharp corner of a steel bundle and the same tension that keeps it in place will slowly saw the webbing apart, sometimes before you're off the first mile of highway. Run one across a finished surface and it leaves a dent or a scuff you'll be answering for at delivery. Dunnage, corner protectors and edge guards are the inexpensive gear that solves both problems at once, protecting the load and the securement that holds it down. Here's what each one does and how they work together on a real load.

Why a flatbed load needs protecting in the first place

Start with what you're actually protecting, because it's two things at the same time: the load, and the gear that secures it.

The serious one is the gear. A sharp edge, cut steel, a crate corner, the end of a lumber bundle, sits under a tensioned strap and quietly cuts into the webbing, and a strap that gives out on the road drops the load. This is the failure that makes the evening news, and it starts with something as small as an unprotected edge. Chains do their own damage, gouging and marring what they cross.

The other thing you're protecting is the load itself. A strap or chain cinched down over a soft, finished or thin-walled surface dents it, crushes an edge, or scuffs the finish, which matters a great deal on coils, crates, finished building materials and anything you're delivering to a customer. On top of both, an unprotected load rubs against the deck, sits unevenly and lets one layer crush the one beneath it.

The three accessories in this post each answer part of that. Dunnage sets the load up and keeps things apart. Corner protectors and edge guards protect the spots where the gear meets the load. None of it costs much next to a load that arrives damaged, or doesn't arrive at all.

Dunnage: the wood, and more, under and between your load

Dunnage is any material you place under, between or around a load to support, separate and steady it. Most of the time it's wood, hardwood 4-by-4s, blocks and boards, sometimes plywood, and sometimes it's foam, rubber matting or pallets. It's the least glamorous gear on the trailer and one of the most useful.

It does several jobs at once. It raises the load off the deck, which lets you run straps underneath it and slide forklift forks under it to load and unload. It separates layers and individual pieces so they don't rub, roll or crush each other, which is exactly what you want under a stack of pipe or steel, usually paired with chocks or stakes to stop anything from rolling. It levels an uneven base so the load sits flat and rides stable instead of rocking. And it spreads a concentrated weight out so a heavy, narrow load doesn't dent the deck or crush whatever is under it. Rubber matting used as dunnage does one more thing: it adds friction, which helps keep the load from sliding.

Placing it well matters. Put dunnage under the load's real support points rather than spanning a gap that lets it sag, keep the sizes consistent so everything sits level and use enough of it to carry the weight without crushing. And remember that dunnage which shifts or crushes lets the load move, so it has to be stable and rated for the weight it's carrying. Getting the load itself positioned and balanced is its own step, covered in how to load a trailer.

Corner protectors: where a strap meets a sharp edge

Corner protectors are the small pieces you set at a corner where a strap or chain bends over an edge. They come in plastic or rubber, the V-board style you'll see most often, for straps, and in steel for chains and heavy loads.

They do two jobs, and this is really the heart of protecting a load. The first is protecting the strap from the edge. A sharp corner under tension cuts into webbing, and a corner protector spreads the strap across that edge so it can't dig in and slice through. That's the difference between a strap that holds the whole trip and one that's half severed by the first hard curve. The second is protecting the load from the strap. Strap tension concentrated on a single corner dents, crushes or scars the load, and the protector spreads that force over a wider area so it doesn't.

Use one anywhere a strap or chain crosses a corner: the corners of a crate, the edges of a steel or lumber bundle, the corners of a machine. And match the type to the job, rubber or plastic for straps and finished loads, steel where chains cross a hard, sharp edge. On a load with sharp corners this isn't an upgrade you can skip. It's the cheapest insurance on the trailer.

Edge guards: protection along the whole edge, not just the corner

Where a corner protector handles a single point, an edge guard handles a length. These are the longer, linear guards that run along an edge instead of sitting at one corner. Some are sleeve-style guards that slide right onto the strap, and some are angle pieces that lay along a long edge of the load.

Reach for them when the whole edge a strap crosses is sharp or vulnerable, not just the corner. Long lumber, steel, sheet goods, a crate with a sharp top rail, anything where the strap lies against a hard edge for a stretch rather than just turning a corner on it. The job is the same as a corner protector, spread along the run: the edge can't cut the strap, and the strap can't mark the edge, for the whole length they're in contact. Sleeve-style guards do a little extra, holding the strap in position and standing up to abrasion along the way, which earns its keep on a long haul.

The simple way to keep them straight: a corner protector covers the point where the strap turns, and an edge guard covers the length it lies against. Plenty of loads want both, a guard running the edge and a protector at each corner.

Putting the three together on a real load

On an actual load, these work in order. Dunnage goes down first, raising the load, separating and leveling it and giving you room to get straps and forks underneath. Then you load and position everything. Then you secure it, adding corner protectors and edge guards everywhere a strap or chain crosses an edge.

Picture a bundle of long steel or lumber. It rides up on dunnage so you can run straps beneath it and it isn't sitting flat on the deck. Where the straps come over the top, edge guards run along the sharp top edges and corner protectors sit where the straps wrap around the corners. The bundle rides the whole way without a strap cutting in and without the load getting chewed up, and you unload gear you can use again rather than webbing that's ruined.

One thing to keep clear: protection makes your securement work, it doesn't replace it. You still need the right number of tie-downs, rated for the load and set at proper angles, hooked to real anchor points. For that whole side of the job, read more about how to secure a flatbed load safely. And treat your protectors like the rest of your gear, inspecting them before each load and replacing anything cracked, crushed or worn thin.

What about insurance and damage protection?

Before towing a rented trailer, contact your auto insurance provider to ask whether your policy covers liability and towing-related damage claims.

Eligible rentals booked through Big Rentals also include Basic Rental Protection at checkout. This added protection can help limit your financial responsibility for certain damage or theft events during the rental period.

For full details on how Basic Rental Protection works, including deductibles, exclusions, and renter responsibilities, review our FAQ and platform terms.

The Short Version

• On an open flatbed you're protecting two things at once, the load and the straps and chains that hold it down
• Dunnage raises the load for strap and forklift access, separates and levels it, spreads concentrated weight and adds friction to keep it from sliding
• Corner protectors go where a strap or chain turns a sharp corner, keeping the edge from cutting the strap and the strap from crushing the load
• Edge guards do the same thing along a whole sharp edge, and many loads want both a guard on the edge and a protector at each corner
• Match the type: rubber or plastic for straps and finished loads, steel where chains cross hard edges
• Protection makes securement work but doesn't replace proper tie-downs, so inspect it all and replace anything worn

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