How to Build a Slide-in Topper for Your Pickup
The cheapest aluminum truck cap is going to cost you $500, and all it does is cover the bed. If you want to protect the floor a bed liner is in order. Before you know it your up to $1,000 or more. And darn if the first time you bump the side of the topper with your elbow, bingo the first dent. There is no strength to those caps, the slightest hit gives you a permanent dent.
You can build a suitable slide in topper that will address your needs much better for somewhere around $100-$125. This is a medium difficulty project you can complete in a good weekend. With only a table saw, or skill saw in the way of power tools, oh yes, you will also need a drill to drive Sheetrock screws.
The list of materials you will need are as follows:
4 ea 4×8 sheets of 1/4″ Luan plywood
4 ea 4×8 sheets of 7/16″ OX Board (oriented strand board)
10ea 2×4’s 8ft long. Might have been a couple more, but 10 is close.
12 ea metal “L” brackets
1-box of 1-1/2″ Sheetrock screws
4 Hinges,
1 Hasp, and Padlock
1-box of 1-1/4″ Nails
1 tube Silicone caulk
1 gallon Paint, oil based
As each brand of truck will have different measurements, this article will give you an idea how to proceed, and what order to do things. Make your own measurements. Measure twice, cut once and you’ll do just fine.
The first step is the bottom box part, what you can’t see when the tailgate is closed up. First step is to take some of the 2×4’s and split them on your table saw. Cut them down to 2×2’s. The reason you didn’t buy them as 2×2’s is this small effort will save you a bunch of money. Plus they will be straighter then the 2×2’s you can buy.
Take one sheet of oxboard, assuming it will lay flat on the floor of your truck. If not, cut it down to size to fit. Be sure to cut it two inches shorter then the inside length of the box. You want to be able to close the tail gate when your done, and the thickness of the front, and rear walls will add over an inch to the total length. Attach 3, 2×2’s length wise, one on each side, and one down the middle. At each end of the 4×8 sheet attach some shorter pieces of 2×2 to fill in the remaining space. Place the sheet with the 2×2’s on the bottom side. Attach the 2×2’s by using the 1-1/2″ Sheetrock screws, screwing down through the oxboard into the 2×2’s.
Cut two pieces of oxboard 8′ long, and high enough to clear the side of the pickup box. Attach them to the sides of the bottom panel already constructed. Attach 2, 8′ 2×2’s along the outside of these vertical pieces of oxboard. Next cut two 8′ pieces of oxboard wide enough to reach from the vertical pieces to the outside of the pickup box. This will determine the width of the topper.
The next step is the front and rear ends. Measure carefully, and determine how high and wide you want the top and sides. You have some flexibility here,. If you want the side walls to be straight up and down, or if you want the top to be higher then the cab. This is the time to make these decisions. Give careful thought to what you intend to use the topper for.
With straight walls it could be roomy enough to be a weekend camper, as well as protect your valuables. Also consider the door configuration. Do you want two doors, or maybe one narrower door. Make both the front and rear walls from 7/16″ oxboard, attaching with pieces of 2×2 and Sheetrock screws. Cut pieces of 2×2 to go all around the perimeter of both the front and back walls. This will allow attaching the sides and roof pieces. On the rear wall, cut out the space for the door/doors.
Next take 3, 2×2’s, and the “L” brackets, and attach one 8′ length in the center running from the front wall to the rear wall. If the 2×2 has a slight bow, arch the bow up, as this is the roof rafter. You don’t want a swayed back roof. Split the distance between this center rafter, and the side wall ,and run another rafter on each side. A total of three rafters should now be in place.
To sheet in the walls and roof of the topper we will use a layer of 1/4″ Luan plywood. Cut the sides first, attach the plywood along the two ends, and the bottom edge. As there should be 2×2 already mounted for that purpose. Next attach 2×2 along the top edge. Be aware that if you have sloping walls the 2×2 running along the top and bottom edges will have to be cut length wise at an angle to allow the sheet material will lay flat and neat.
With the sides done, cut panels of Luan for the roof. Two pieces meeting in the center will do the trick. The final sheeting will be to cover the oxboard on the front and back with Luan plywood. You can use smaller pieces, just remember to be neat. Seams will show so you want it to look uniform. Build the door/doors from oxboard, and add a layer of Luan as a finish surface.
How you trim out the edges of your topper is up to you. Aluminum angle trim pieces can be bought in 8′ or 10′ lengths. Look in the siding or flashing department of your home center. You could cut strips from a 2×4 about 3/8″ thick, as a cheaper alternative. Either way, be sure to run a good bead of silicone caulk along each edge of the luan before covering the seams with trim. Use the nails to attach the trim work. Be sure to cover all seams with trim to assure there will be no leaks. Mount and trim out the doors, and it is complete.
The final step is the protective finish. There are a couple choices, stain topped with polyurethane is one, but an oil based paint is the longest lasting. Also it will be less likely to leak. Be sure to prime with a good quality primer, then apply two good thick coats of paint. Making doubly sure you get paint into all the crevices along the trim.
The end result is a strong and good looking slide in topper, that can be easily removed by three people. One on each side, slide it back and place the back end on the ground. With one person on each side holding the front edge off the truck, the third person can drive the truck out from under the edge and it can then be set down on the ground. With reasonable care this topper will last for years, and you have the satisfaction of knowing you made it yourself.
