TORONTO – What killed your trailer floor? I suggest it was death by moisture. But it probably didn’t decay. The wood likely snapped first.

Van trailers can carry any number of things, and their interiors are designed for strength, durability, longevity, low maintenance and light weight. But most dry van trailer floors running out there today are laminated oak or maple, and-especially near the rear, and when doors are open- are vulnerable to exposure to rain or snow.

You already know that wood and moisture don’t mix well.

According to Canadian floor builder Prolam, wood floors are at their optimal durability with between 12 and 18-percent moisture content, where maintenance costs will be minimal.

The more moisture your wood trailer floor absorbs, the less durable it will be.

As a result, it will likely crack and need repairs or, worse, early replacement.

“Problems with wood trailer floors start when the moisture content surpasses 20 percent,” Cap-Saint-Ignace,QC.-based Prolam claims. “But you’ll be surprised to know that trailer floors rarely decay.”

Prolam claims it takes moisture levels of over 30 percent for wood to decay, but once your trailer floor has gotten to 25-percent moisture levels, it’s already lost about half of its strength and is at risk of breaking.

Luckily there’s lot you can do to protect your floors and lengthen the lifespan of your trailer.

Smart spec’ing and maintenance

“The biggest problem I see today is that because of the recession, fleets have older trailers,” says John Carr, VP of sales and marketing at Havco Wood Products. “Because the trailer floor is wood and it’s a natural product, it gets weaker with the more load cycles you put on it so it eventually will break.”

The life cycle of a trailer floor naturally depends on the application for which it’s used, but preventive maintenance and proactive repairs will go a long way in helping trailer flooring from failing. The first step in floor maintenance, however, happens before the trailer hauls its first load.

Trailer dealers will work with trailer builders and upfitters to spec trailers according to customers’ applications, regardless of the size of your fleet.

Here are some things to think about:

• Consider how long you need to keep the trailer for, where your runs are and also the type of load you typically haul.
• Ask yourself not only what you’ll haul, but how you’ll load the trailer. Consider floor system designs, such as the spacing of cross members, and how you should match the floor with the weight and layout of freight.
• How will loading and unloading take place? Will your floor need to be able to frequently take the combined weight of the freight as well as a forklift, or will you most often use a pallet jack?
• What about climate? Humidity takes a huge toll on floors. Do some of your trailers start the week in, say, Regina and wind up in Texas? Temperature and humidity changes will affect the performance of your wood floors. (One solution for that, experts suggest, is spec’ing a floor with an adequately sized crusher bead that lets boards expand, preventing buckling. “If you have water infiltrate the floor; when wood absorbs moisture, it expands and as it dries it contracts; it’s like a paper clip-you keep bending it back and forth and eventually it’ll break,” Carr says.)

Which brings us to best practices: 

• Close trailer doors whenever possible, especially in wet environments. Carr says shippers will often leave trailer doors open at decks to see which trailers are empty. That wreaks havoc on trailer floors; and everyone knows that it’s the rear part of the floor that rots first. And try to avoid cleaning the floors with water. Air pressure or maybe just good old-fashioned sweeping will take care of things and make your trailers live longer.
• Inspect trailer floors of all types regularly, and don’t forget to look under the trailer, too. Damaged sections of floors can be patched up with repair boards. Carr says the first sign of water damage is glue lines delaminating. Havco also has a free online guide for repairing laminated wood floors. Rockland Flooring suggests looking for spills or debris on or between the floor boards. Watch for splitting, cracks, gouging, blacks stains, spaces larger than 1/8 of an inch around hook joints; cracks, chipping or wear of undercoating.
• Shield your floor with water-resistant wood treatments. There are many materials that penetrate the wood’s surface and prevent water absorption. Prolam offers P.u.R undercoating, designed to protect the “bottom” of the floor from splashes of water and moisture, and factory-installed Waxim and Waxim 100 treatments to protect the top side of your trailer floor. Rockland offers Floor Saver, an undercoating for the underside of your floor that Rockland claims to have an anti-fungal component, and Grip Guard, a top coating with a traction compound. And Havco offers FloorShield, which can be applied at the factory or afterwards, as needed. Carr says it can be used in dry vans, containers or straight trucks, but not flatbeds because it doesn’t have UV protection.

Keeping dry vans dry

• The underside of trailer floors can break down when subjected to intense water spray and road debris. Specific areas, like around the wheels, are more prone to degradation. Once water-based paint breaks down, the wood absorbs moisture, causing warping, swelling and deterioration of glue bonds. Carr says: “The tires splash water and other particles from the road onto the underside of the trailer like sand mills.”

Treatments: That’s why floor manufacturers offer water-resistant wood treatments for the undersides of the trailer floor, too. Composite floors are also available. Havco, for example, has been making composite floors since the 90s, but released their newest Fusion Floor composite in 2012. It has a top layer of laminated oak and a bottom layer of fiberglass and the company says the floor is lighter, stronger and more water-resistant (the fiberglass on the underside of the trailer floor absorbs less water than wood, acting as a barrier between the hardwood floor and water).

• Those first eight feet: That’s the most vulnerable part of your floor. It’s this area that most needs a water-resistant top coating. Trailer manufacturers offer steel threshold plates of varying lengths, which protect the rear wood floor from damage and/or steel floor extensions, which also help eliminate wood damage at the rear of trailers.
• Hook joints: A typical laminated hardwood floor has more than 2,000 joints-an average of 5.6 joints per square foot. Conventional trailer wooden floors are laminated from oak or maple, with each stick in the laminate keyed to the next in the laminating/gluing process with a simple hook joint. Prolam uses a patented Zig-Zag profiling of the ends of each stick in the flooring laminate strips. Instead of the hook joint between adjoining sticks, which can resist shear in one direction only, Prolam’s Zig-Zag design is built to mechanically transmit vertical loads at both sides of the joint, evening the stress distribution of point loads such as the wheels of a fork-lift truck. Prolam claims the joint design also acts as an extra barrier to the seepage of water through the joint area.