Utility Trailer Bed Replacement--what to use?

[Paul F Franklin]

I've an older Thule utility trailer (from back when Thule made utility trailers) like this one:

Thule trailer.JPG

The original bed is pretty much shot so I need to replace it. The bed itself is 101" x 59" x 1/2" thick and is made of what appears to be plywood with a thin layer of dimpled, rubber-like material on the top surface. It's supported on all edges and by 2 heavy u channel ribs that run from front to back (along the long dimension). The thing has hauled many, many tons of "stuff" from gravel to equipment and machinery to lumber. It sits outside year round, uncovered.

I haven't been able to find any suitable sheet material that is big enough to replace the bed in one piece. So my current plan is to special order two sheets of 4 x 10 x 1/2" marine ply and place it so there is a single, long seam over one of the supporting ribs. Then I plan to apply a couple coats of roll-on truck bed liner. It looks like I can also get 4 x 10x 1/2 MDO, probably a lot cheaper than the marine ply. I think the marine ply might be better but the MDO might be good enough?

Anyone have a better idea for material or see any problems with this approach?

[Scott Winners]

I guess it depends on what you usually haul, and how bad your winters are in NE Ohio.

There is a "trailer grade" for flooring in...hang on... didn't find it quickly in the NELMA guide. I think the 'trailer grade' was for mixed oak. It is going to be 6/4 or 8/4 most likely, heavier than 1/2 marine grade and I dunno relative price of either right now. If your truck can tow the added weight and the trailer suspension can handle the added weight (and your wallet can handle the possibly higher price) I would expect trailer grade boards to be longer lasting and stronger the whole lifespan. You did say occasional gravel and equipment. For lumber I would expect half inch ply wood be adequate.

There is another guy also named Scott here who knows a BUNCH about trailers. I remember he lives in North Carolina and in his profile pic there is an enormous tree stump behind his left shoulder, but I don't remember his last name. He will steer you right if he stops by, and can probably talk your leg off regarding the relative merits of trailer grade oak versus marine ply.

Good luck. I did find "T&T" as in truck and trailer grade stamp in the WWPA (Western Wood Products Association) grading book fairly easily. Not the prettiest boards in the warehouse, but tough as nails.

[Maurice Mcmurry]

I used 3/4 marine Fir and coated all surfaces with Jasco copper green wood preservative. Pontoon boat decking is a great product it is CCA treated marine ply. It is 3/4 as well. I might consider redoing the edge to accommodate 3/4.

Pontoon Boat Decking - Marine Grade Plywood

[Jim Becker]

Looks like that trailer is from the era when Thule was also involved with Brenderup (EURO) horse trailers. Same floor design and yes, it was a plywood product. It's hard to source material in the US at that size with an exterior rating, unfortunately. So your solution to seam over a support is pretty much about the only way to do it with sheet goods. Go with the Marine Ply. MDO is nice, but it's not really going to hold up on the surface to the kind of abuse that a trailer floor brings to the table, as it were.

That reminds me...I really need to replace the piece of marine plywood that makes up the floor of my own 5x8 utility trailer that I've had since 2006. It's still solid, but really weathered hard. Fortunately, the design of my LoadRite trailer uses a standard 4x8 sheet of wood as the additional width was done with metal.

[Tom M King]

What do the supports under the bed look like?

[Paul F Franklin]

Thanks all! Scott, I could go the solid lumber route, but the smooth surface is so nice when shoveling compost or the like out of the trailer. My equipment trailer has pressure treated 2x for the deck and they move all over the place with the weather. The trailer's rated to haul one ton, so the extra weight would not be an issue. So it's an option. The boards would have to run side to side because of the supports underneath.

Jim, Thule made (or sold) nice trailers...this one is tilt bed and the front and back gates fold down or come off. They made a slightly larger two axle version that tilted either back, like normal, or to the side. Not sure how useful that was but it looked cool. Agree with you on the preference for Marine Ply.

Maurice, thanks for the tip about pontoon boat decking; I wasn't aware of it and since it comes in 8 1/2 foot lengths it would be perfect. And I think 3/4 thickness would not be a big issue. Unfortunately, the site you linked to requires a minimum order of 4 sheets (but they have free shipping! For plywood!) But there are loads of pontoon boat dealers around here so I can see if I can source it through one of them.

Tom, the deck rests on a lip all around the edges and then there are two flanged c-channel ribs (hat channel?) running from front to back that support the bed at the 1/3, 2/3 points of the width.

[Perry Hilbert Jr]

I have had a 13 x 7 flat bed dual axle trailer for almost 30 years. Pressure treated 2x10's. Replaced the floor twice in 30 years. I have a little 6x4 trailer I bought for $40 at a yard sale. It had a crappy plywood bed and sides. I stripped the trailer down, pulled off the wiring and lights, replaced the bearings, repainted, rewired, new lights and put 1x6 pressure treated decking on the floor and sides. It can go behind the truck, the SUV, the ATV or the lawn tractor. I have probably pulled that thing at least 5 k miles. Even used it on the beach with golf cart wheels and tires. The decking and sides have held up beautifully, despite hauling mulch, dirt, rocks, gravel, firewood, etc.

[Maurice Mcmurry]

ACQ treated wood is corrosive to steel. CCA is still available but is not easy to find.

[Jim Becker]

ACQ treated wood is corrosive to steel. CCA is still available but is not easy to find.

That's a good point, Maurice. My trailer is heavy galvanized, but I'm guessing it could still be a factor if/when I do a replacement.

[Tom M King]

So the side to side supports are about 30" apart? I would probably get a sawyer to cut some White Oak boards thick enough to run front to back, rabbet the edges to fit, and plane the top surface. Safer for the metal than today's treated wood, should last more than a decade, and front to back shouldn't be too bad for shoveling.