Truck Mod: DIY Wood Flatbed Deck for Truck Campers

Let me start by saying that this project is not approved or sanctioned by any one who is an engineer or a governing body of any sort. Should anyone decide to follow my lead, then, “you go, boy,” just don’t be try to sue me later because I said it could be done! I firmly believe everyone should be responsible for their own work and ideas, it kind of keeps life interesting that way. That being said, I can find no reason or explanation why building a flatbed or flat deck out of wood, shouldn’t work.

And forgive me for the rather long dissertation on this topic, but considering this concerns the structure of the back part of your truck, and you may be building it yourself, and putting a rather large, heavy object on it, I felt it best to convey as much info as might be necessary.

To digress a small amount, I’ve owned many trucks and campers over the years. In the normal configuration that most folks are familiar with, some of which were woefully overloaded, mostly out of my own stupidity. But fortunately, I did not hurt anyone or myself. I’m older and wiser now, and have accumulated enough experience over time, that I believe I am making an informed choice with this project.

My last truck was a steel flat deck. It had my camper mounted on top, some wooden boxes I built on top, and some aluminum boxes underneath. This set up worked exceptionally well. The amount of extra storage and usability is simply way beyond a normal box style bed. Granted, it is not the most pretty looking set up, some may even call it ugly, but others will see the benefits to its design and simply have to try it. And the more you look at it, the better looking it gets.

I have noticed over the years that many trucks with steel decks look like crap after a few years of use in the north country of British Columbia. This is because we use salt and calcium on a lot of our roads, which is not very gentle with steel. My steel deck is a perfect example of this, but the aluminum boxes I mounted underneath are still in respectable shape, again not shinny pretty like new, but way better than rusty looking steel. So initially, my search was for an aluminum deck for my new Ford F550. This is with full upper and lower boxes, custom built to fit the camper.

After a few phone calls and a couple of chuckles, I discovered that this was going to set me back in the neighborhood of around $20,000 US dollars. Too much for my blood. So, as the search continued for a less expensive solution. I soon realized that by the time I purchased an aluminum deck, then added all the upper and lower boxes, I was still into this project for around $15,000 or more. Better, but still not in the ball park where I really wanted to be.

Probably the biggest thing that held me back was the fact that most of the pre-made decks are of a certain size. That makes sense, that way manufactures can build them at scale and at a more affordable cost. The truck camper I have has a generator built-in, the plate under it sticks down about 1.5 inches, so the camper would have to be raised even higher on the deck or the deck would have to partially cut away. Then there was the issue of the generator exhaust pipe sticking down, would there be a cross member in the way on the pre-made metal deck? Did I really want to spend a lot of money on something brand new only to start cutting and welding, and I don’t have an aluminum welder?

I have seen a few campers that just move everything back another 6 inches or so, but this then also moves your center of gravity further back as well, and increases your overall length. This in turn affects maneuverability, handling, extra long hitch extension etc. I didn’t want to go there. In the end, I could not find a pre-built deck that would suit all my needs, and I was not going back to a metal deck because of the rust and maintenance issues needed over time. Frustrating to say the least, and a custom deck puts you back into the big dollars again. There had to be a better way.

I have built a number of structures in my life and have always been impressed with the durability of wood. I have seen some construction that just plain makes you cringe and wonder how it managed to stay upright for so many years. Wood is pretty strong, forgiving stuff.

So while doing some serious research, basically looking up at the pine trees and marveling at the amount of flex they can withstand in a heavy wind without breaking, the proverbial light went on. Why don’t I make a flat deck out of wood? I could make it exactly to the spec’s I want, and it is super affordable compared to all the other options I was looking at? The more I thought about this, and the more ideas I got, I just couldn’t stop until I could find more answers.

I asked a few people whom I knew who had some experience with flat decks, and construction, a few engineering types, mostly people who’s opinion I respected. I got some mixed opinions, some good ideas, and got a few laughs, however, I’m sure the Wright brothers had more than a few people chuckle at them initially. I thought of the number of wooden boats that have and still are being built today, a wooden train trestle still makes me wonder at the amount of weight being put on it, not to mention the vibrations and twisting, but they still stand. So, it was time for an experiment.

I spent many hours scouring the internet for info on building a wooden flat deck. As you might imagine, there are many people who have done this to some degree, but one has to question how well some of them worked out. I found one video on YouTube. It was a time lapsed affair of a gent with a Ford F-450 who built a wooden deck with racks. It looked like it would work pretty well. I borrowed a few ideas off of his build, and from looking at many other decks, including my old steel deck.

Most decks are built with two stingers running down the length of the frame rails. Regardless of what they are made of, they are attached in two or more locations on the frame, depending on the length of the deck being built. I thought of running the horizontal 4×6’s directly on the frame and eliminate an extra 3 or 4 inches of height, but then that complicates where you can attach the brackets to the frame. There are an awful lot of wires, fuel lines, etc running along the frame of a truck, be careful where you drill a hole. It would also require me to create raised fender pockets, not a huge issue, but then this makes building the upper boxes considerably more difficult, and because of the odd shape would be less usable space. There are always trade offs. I chose to go the simpler route. The beauty of building it yourself is that you get to do what ever you want, and if you don’t like it, take it apart and change it, it’s not that hard.

Another concern I had about using wood was just how well this is going to hold up over time. A lot of that will have to do with the type of wood you choose to use, treated or not. I went with Douglas fir, as I could get it locally and it is a very strong wood, a tight grain Southern pine would likely work well too. I spent $500 Canadian for the lumber I needed and I didn’t use it all. If I had to replace the whole thing in 10 years, I’m still coming in way less than anything I could buy!

I wondered about durability, I think it is actually good that wood flexes a bit, some people worry about frame flex and whether this will start pulling the tie-down mounts apart on your camper. My camper is an Eagle Cap 1200, she’s a heavy girl, and we do lots of off-road camping, wash board roads, two tracks etc, I have had no issues in 18 months. I snugged up all the bolts holding the deck together after a month, my wood was still a bit green, and since then, have not had any issues with anything coming loose. Keep in mind that wood is always in a state of flux, it is either absorbing moisture or releasing it, and therefore it will always be expanding or contracting, I wouldn’t get too worried about it. Think of the weather you will see during an entire year.

Safety was another issue I considered, especially carrying a 6,000-pound camper. But again there are no “plans” that one can buy to tell you how to go about building your own wooden flat deck, they have them for truck campers though. I could find no information regarding what is considered proper building techniques or mandates, but most decks are built along the same lines. Flat decks are also not something that are crash tested, nor are campers or trailers for that matter, I figured just build it strong and it should be fine. So far, so good.

After mounting the camper on the deck for the first time, I was naturally a little nervous, and drove around with my window down most of the time listening for any unusual sounds. In my part of the world there is still snow on the ground in March. It was a tad chilly driving around like that, plus I’m getting older and a little hard of hearing, not sure what I was expecting to hear, but it was refreshing! In the end, I didn’t hear any splitting wood or anything that sounded catastrophic. I will say that in the winter while out camping, the underside will get coated with snow and slush and ice while driving, then you park for the night and everything freezes up solid. In the morning when you go to leave, you will hear some odd sounds because the surface ice will be breaking up and the odd board might be moving a hair, but upon inspection, everything will be as per normal.

I still had my old 2014 F-350 dually flat deck in the yard with my 10.5-foot Okanagan on it, another heavy camper. I had Rancho 9000XL shocks on all four corners and this rig rode pretty stable, so I decided to do a direct comparison with the new truck and camper. My driveway is a bit of a bush road that wanders all over for about 1.5 miles until you hit some gravel. It definitely gets anything rocking while driving, so I figured it would be a good test for flex and movement. I did this a couple of times one after the other with each truck, at different speeds, and with the wife following behind keeping an eye on the action (she’s a good woman), oddly enough, the F-550 with the Eagle Cap and wooden deck was more stable than the truck with the steel deck. Yes, I know, this isn’t apples to apples, but damn close considering the Eagle Cap weighs almost 2,000 pounds more! After a year of driving around like this, it is a very comfortable set up. There is very little swaying and the camper has stayed put on the rubber bed mat I use.

Okay, time for the picture part of this project. This is what you get when you order a cab and chassis truck—no spare tire mount, no hitch, and no bumper. These are generally dealt with when you buy the deck. The truck is a 2022 Ford F-550, 4×4, 7.3L gas engine, 10-speed tranny. It works like a charm hauling my heavy camper around.

I had spent many hours designing the deck ahead of time. That was probably the hardest part, although enjoyable in the end when it all came together as planned. First step is the stringers that sit on top of the frame rails, I used 4×4-inch Douglas fir. The front and rear are attached with Grade #8 bolts through the frame and stringer with 1/4-inch steel plates. A lot of flat decks will often only have them mounted at the front and back. I chose to use some large square U-bolts in the middle for extra security. Also, if the wood was ever to split length ways, the u-bolts would help to prevent any separation, or at least somewhat.

Next up was the horizontal stingers. These were 4×6 inches. I ended up planing them down to 3×6 inches. It was just looking a bit too high. In hind site, I should have planNed all the stringers to 3.5 inches, but I wasn’t about to start going backwards, and my hands were getting cold! I put blockers between all the stringers to prevent any movement, probably over kill, but I wasn’t worried about the weight it’s an F-550. These boards were held in place with some 6-inch wood screws until I could get the brackets welded up.

For the brackets, I used 4×4-inch x 1/4-inch angle iron and then welded in gussets with more 1/4-inch plate, some rust paint and stuck them someplace warm for a few days and it was time to attach them. I used a lesser grade galvanized carriage bolt for the brackets, but considering that I was using twice as many, I am not concerned about the strength factor here. Also, by using carriage bolts, you don’t need to put a wrench or socket on the top part which will be under deck boards, too snug them up when required. I have a drill press, which makes drilling holes in steel a whole lot more fun, but you could do this with a hand drill and a vice, been there done that. Or, just get a fabricating shop to make these up for you. It wouldn’t be that much more expense. I also counter sunk the bolt heads about a 1/4-inch on top so that when I put the deck boards on they wouldn’t be uneven, or sitting up in those areas.

Even though I had about 3 inches of clearance between the exhaust and this one cross member, I decided to make a heat shield for it. I’d feel pretty stupid rolling down the highway with my deck and camper on fire!

For many years I have driven around staring at the spare tire mounted on the front of my truck, and although I have never had an issue with over heating, I just wasn’t real thrilled with how it looked. So, because I decided to mount my spare tire under the wing of my truck camper, I need to fit the tire between two of the stringers, and I also needed to modify the aluminum box underneath it. Measure three or four times here folks. You don’t want to get this one wrong! Once you cut out the offending piece, just flip it over and attach it with some spare metal pieces and heavy pop rivets, and you still end up with a fully functioning box. I also used that 4-inch wide RV roof tape and covered all of the metal I riveted, it has been water tight ever since.

It doesn’t look too shabby. Yes, I can unbolt that tire and tilt it out with the camper in place. It’s a heavy bugger though. You might notice that the rear aluminum boxes are a wee, bit lower in height than the front ones. This was done to try and keep the departure angle with the back of the over hang of the camper. It’s not like you’re going to be doing any extreme four wheeling with one of these big baby’s, but it’s always best to not be dragging anything. I also raised my rear camper jacks up one bolt hole, about 6 inches. They sit nice and flush under the back and you’re not likely to catch one as easily. It was also a bonus having the rear box a little shorter as it would have hit the exhaust pipe, as it was I added an extension to get the exhaust out from underneath the box. All the lower boxes are through bolted with carriage bolts as well. they add to the structure and stiffness of the deck too. I can carry a 5 gallon fuel can and a 20 pound bottle of propane on it’s side in one of those boxes, or my Honda EU2000i generator plus extras. Then there are the rear boxes, then the upper deck boxes, the rear of the cab, and then the entire truck camper. The storage and convenience factor is crazy. Once you experience a set up like this, you can never go back to a regular, box style truck. It’s as handy as a pocket on a shirt.

I got my sweetie to give me a hand with the deck boards. Those we planed down to 1.25 inches and spaced them 1/4-inch apart for ease of drying and used GRK structural screws to fasten them down. You can see the notch I left at the back left to accommodate the generator plate. There is just enough room for the generator exhaust pipe with out touching or burning the wood. You will have to install the fuel line and cap mount. It was included, not very hard, just make sure you keep a slope on it or you’ll be cursing every time you fill with gas. I didn’t go overboard with the lights for the deck. These meet the highway requirements for a truck like this, besides, the camper has all the same lights and more. I also wasn’t concerned with putting some big heavy duty bumper on it either. The trailer hitch is rated for something hugely ridiculous, nothing is getting past that. There are steel frame rails behind the wood face, plus all the big lumber pieces, not to mention 3 feet of camper first. If somebody manages to get that far under my rig and slam into all of that, I’m gonna have way bigger problems to face.

I also built some wooden boxes to go on the top part of the deck. I used 3/4-inch plywood and some of the left over Fir I had hanging around. You could go with aluminum boxes, but I could find none that were really a nice fit for under the camper wings. They were either too tall, too short, or too wide. If you want maximum amount of space, you’ll either have to go custom built aluminum which is mucho dollars, or build them yourself. On my last flat deck build, I used all plywood boxes and painted them black. In six years they held up really well, never got any water in them, but the faces of the plywood did start to lift a bit. This kind of makes sense, they are the most exposed to the elements, but the rest of the box was in perfect condition. By using fir on the faces this time, if it does weather a bit, all I have to do is sand it down and reapply some stain and I’m good to go. The matching Buyer’s latches were a bit of pain to make work with 3/4-inch material, but other than that nothing too challenging.

You may notice that the front box is narrower because of the spare tire behind it. This is easily removed in less than five minutes by taking out two bolts and two lag screws, then you have access to the spare tire. Still a very handy cabinet to store things in, and hey, it’s an F-550 and you don’t have to worry too much about carrying stuff, you have lots of payload capacity. And if your getting to be an old fart like me, and have some back problems, you might need some help lifting that 19.5-inch spare tire back up on the deck after you’ve had a flat tire. I welded some tabs onto a spare 2-inch receiver hitch, bolted that to a cross member under the deck, and bought myself a game hoist for lifting critters you intend on gutting and cleaning. Hey, if it will hoist a dead deer it will lift a spare tire. You don’t actually need it to lower it, I just undo one nut on the rim bracket, and pull the tire forward and gravity will do the rest. But it sure works slick lifting the tire up so that you can slide it back into place and get on your way. I could actually shorten some of the pieces as they are more than long enough for a tire, but they all fit comfortably in the rear box, so not a real priority at the moment, but might be useful for something else that I haven’t thought about yet.

At this point, I’m sure you’re wondering how many hours this might take to build? I have to be honest, there was snow on the ground when I started all this, still winter in my neck of the woods, so between welding outside in the cold, waiting for paint to dry inside, and some days that were just too damn nasty to work outside, it is hard for me to give you a real accurate time frame. I would have to say that to build the wooden structure is only a few days, mounting the lower boxes and modifying what has to be modified, obviously more time. The wiring is mostly plug and play harnesses bought off of Amazon, depending on what brand of truck you have. The additional lights on the deck to make it street legal are all screw on types, just a matter of drilling a few holes and running a few wires and making connections. If a person was to set their mind to it, and depending on how handy you are and what type of tools you have, you should be able to knock one of these off in a week or maybe three to four weekends. Remember, it’s all pretty big chunks of wood you’re working with here, it’s not fine carpentry. It’s kind of like working with big Lego pieces, but you have to bolt and screw some of them together.

As for the price to build a wood deck like this, here is my break down, roughly.

  • Wood for the deck – $500
  • Hardware: steel, bolts, structural screws, etc. – $300
  • Lighting and wiring harness – $250
  • One 2.5-inch hitch – $530
  • Aluminum under deck boxes from – $2,660
  • Upper wooden boxes for both sides – $500
  • Spare tire hoist and receiver for old farts with bad backs – $180

For a mere $4,920.00 Canuck Bucks and a little sweat equity, you too can make your very own wooden flat deck for your truck. Now, how cool is that?

About Kevin Mooney 1 Article
Kevin Mooney served in the navy and civil service and enjoys the great outdoors. His hobbies including building things including cabins and other structures, and camping. Over the years, he's owned several truck campers including his current camper, an Eagle Cap 1200. Kevin, along with his wife, are currently living off-grid in a little cabin on a lake in Northern British Columbia.


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