Which oak is best for trailer decking?

The legal requirement for trailer flooring in the Code of Federal Regulations (CFR) is not a difficult standard to meet. The standard is provided below, but to oversimplify the statute in the CFR, a trailer floor needs to be well constructed with no holes, tight enough to minimize the ability of gases and fire to permeate it, provide some traction, and kept reasonably clean by the trailer owner. This may sound simple enough, but there are many flooring options on the market and decisions in this area can be more complicated than originally anticipated for trailer manufacturers. Not all trailer flooring and installation techniques serve the same purpose, nor do they last the same amount of time. The customer’s intended use, price point, and durability factors all come into play when deciding which flooring material to use for a specific trailer build.

The direct wording of the flooring statute reads: 49 CFR § 393.84 Floors - The flooring in all motor vehicles shall be substantially constructed, free of unnecessary holes and openings, and shall be maintained so as to minimize the entrance of fumes, exhaust gases, or fire. Floors shall not be permeated with oil or other substances likely to cause injury to persons using the floor as a traction surface.

The following types of flooring options meet the necessary requirements but serve different needs and are offered at different price points. In the open-top and livestock trailer industries, the most common decking options are southern yellow pine (treated and untreated), rough oak and Douglas fir. Each option comes with its pros and cons and knowing the differences is vital for choosing the best product for your trailer.

Southern Yellow Pine

Southern yellow pine (SYP) may be the most frequently used wood trailer decking material. It is widely available in North America as it is grown 35 percent faster than it is being cut which also makes SYP the most affordable decking product listed in this article. SYP is used for trailer decking for two main reasons: its strength and its ability to absorb treatment. Even though it is not considered a hardwood, pine is a very strong fiber. The cell structure of SYP allows for better chemical absorption than any of the other materials listed, which means it is more resistant to rot and decay. Untreated SYP does not have this benefit.

The downsides to SYP include its common defects such as knots, wane and warping. Knots create weak points in the board while wane gives rounded edges instead of flat surfaces and sharp corners. The cell structure of SYP that allows it to absorb treatment so well also allows it to warp and twist if not properly dried after treating.

For decades, trailer manufacturers have bought SYP based on the Southern Pine Inspection Bureau (SPIB) grading specifications. This system gives lumber a grade with number one being the best and number four being the worst. It would appear that buying number one or number two would provide higher quality, more useful trailer decking, but that is not always the case. The SPIB grading specifications were developed for the building and construction industry and are meant to grade lumber on its strength when used vertically. Horizontal use, such as trailer decking, requires different specifications.

Rough Oak

Rough oak is used for trailer decking primarily for its strength. Oak is one of the only decking materials recommended for use with tracked equipment such as skid steer loaders and excavators.

In the trailer industry, oak decking is referred to as “rough” oak for a reason. Unlike SYP, oak is typically cut with a band saw rather than a planer. Rough oak is less uniform in shape than SYP or Douglas fir. The availability of oak is not as prevalent in North America as SYP. Penetration is the depth to which preservative chemicals are forced into the wood and is an indication of the amount of protection provided. The amount of penetration is determined by the qualities of the species and the treating process. The greater the depth of penetration, the less likely it is that the protected boundary of pressure-treated wood will be breached. The properties making oak strong also make it dense and heavy, and the cell structure of oak does not allow for optimal chemical penetration and retention.

Douglas Fir

Douglas fir is desirable because it contain many attributes not found in SYP. Douglas fir typically has much less wane and much smaller knots than SYP. This makes it easier to find usable boards. Douglas fir is a more stable fiber, which leads to less warping than SYP.

However, without an expensive process called insizing in which the wood is prepared for preservative treatments, Douglas fir does not absorb treatment well. This leaves it more vulnerable to rot and decay. Another issue with Douglas fir is sourcing as it grows much slower than SYP and longer length boards are more difficult to source. These factors make Douglas fir a more-costly decking option.

Steel Decking

Steel is one of the toughest common alloys. Traits such as durability and dependability have long made steel decking a popular choice in trailer manufacturing. Steel is stronger than aluminum in the sense that it has a higher modulus of elasticity, which means more force must be applied to steel before it starts to bend.

The biggest pitfall of steel decking is the fact that steel can rust and thus need to be examined frequently so repairs can be made to prevent further rusting. Scratches in the paint must be touched up or they will begin to oxidize. If the steel has been galvanized, inspections for rust are not required as often. When repairs are made on galvanized steel decking, the galvanic layer must be removed before welding. Rust not only has a negative aesthetic look, if not addressed it will weaken the structural integrity of the trailer. The labor costs associated with repairing steel trailers are often more expensive than similar repairs on aluminum trailers because steel trailers must additionally be repainted after repairs in order to prevent rust. In wet conditions, steel decking can also become very slick and due to the weight can decrease the cargo capacity.

Aluminum Decking

Aluminum decking is a desirable option for trailers because it is lightweight. Not only is aluminum corrosion and rust resistant, many trailer towers find aluminum trailers easier to pull because they are weigh less, which also translates into better fuel economy. The lighter weight of the trailer itself often translates to a higher cargo capacity on a trailer with an aluminum deck.

Both steel and aluminum trailer decks require upkeep, but one of the larger issues with aluminum trailers is simply lubricating the hinges and cam latches. There are some negative aspects of aluminum trailer decking. Aluminum is typically not as dense and strong as steel, causing some experts to argue aluminum trailers cannot withstand the stress of trailering as well as steel trailers. Aluminum trailers tend to be more expensive than steel trailers. Also, an aluminum deck may not be appropriate for hauling some equipment. Depending on the application an aluminum deck trailer is used in, the deck may be slippery in adverse weather conditions if no additional changes to the deck are made.

Rubber

For those wanting to get more life and use out of their trailer deck, there are a few premium upgrade options. NATM members such as Shelby Trailer Flooring and Rumber are both decking products made primarily of rubber, not lumber. Rumber uses plastic material with rubber for stabilization. The non-lumber products both have their pros and cons as well. Rubber does not rot like lumber does, so it can last longer without treating or coating, and it offers better surface traction than typical lumber decking.

The tradeoff for these non-lumber materials is weight and stability. Being made of rubber instead of lumber means these products require additional trailer frame and cross bracing when replacing lumber decking. These dense rubber products also weigh significantly more than lumber decking which decreases the cargo capacity of the trailer assuming all other features of the trailer remained the same.

Blackwood Lumber

Another NATM member, Blackwood Lumber, offers a decking product that falls between the lumber and rubber categories, making use of both. Blackwood is manufactured using treated southern yellow pine (SYP) and industrial grade rubber. With Blackwood, the structural integrity of the board is maintained, and traction and durability are added through the rubber infusion. When loading and unloading a trailer with typical lumber decking in wet conditions, this flooring option offers improved traction, even in wet, slick conditions. The rubber infusion also helps protect the board from heavy impact and the sun’s UV rays.

Blackwood Lumber offers three products: Blackwood Classic, Blackwood Pro, and the recently released Blackwood Max-Trac. Blackwood Classic keeps the exposed lumber strips for those that like the classic look. The surface of Blackwood Pro is fully covered by the durable rubber. Blackwood Max-Trac has raised, arrow-shaped cleats for maximum traction. For more information about Blackwood Lumber, visit www.BlackwoodLumber.com or call (903) 705-6982.

Images provided by Logan Sartain of Blackwood Lumber displaying some common trailer flooring options, as well as illustrating some common trailer floor damage.  

Blackwood Lumber in an agricultural application.

Blackwood Lumber utilized on a backhoe trailer.

View of the deck of a trailer utilizing Blackwood Lumber.

Common wear and tear and damage on a trailer deck.

Overhead view of a trailer with common wear and tear and damage.

Blackwood lumber utilized in a smaller tilt bed trailer application.

Blackwood Lumber flooring providing enhanced traction.

Blackwood Lumber Specific Articles

Industrial Wood Technology developed LOKT as a trailer specific decking product. LOKT’s specifications are tailored for the trailer industry to provide stronger, longer lasting boards and less downfall. LOKT’s features include minimal knots and wane, and precise moisture levels to minimize warping. LOKT takes the guesswork out of trailer decking, consistently providing quality boards.

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