I've started the process of building a truck bed shell to protect my gear while traveling. The primary goal is to hold my bike(s) and skis while I travel around the country. I intend to have a travel trailer (A-frame or an old school tear-drop) so my cap isn't going to be an RV, but a shell.
That said, I do plan to be able to sleep in it for short periods of time without the need to haul the trailer. It is going to be hard sided, although not necessarily insulated. It will have a pop-top a la Westfalia with solid walls that fold up like an A-frame trailer. I'll be able to sleep under the raised roof in a bunk but also on the truck bed floor when stealth is required. When I'm traveling without a trailer, I'll be able to camp in the truck but it will be minimalistic.
Design considerations:
The overhang at the back is no further than the tailgate, 1 1/2 feet beyond the bed; parallax is at play in this image. It is 10 feet long overall. Overall it will be 35 inches tall from truck rail to edge of the roof. The undercut at the rear is deliberate and will give me the walk-around space in the garage when the bolt-on section is removed.
The sides are 3/4" AC exterior plywood, the bulkheads (perpendicular to the sides) will be 1/2 AC exterior. The sides will be reinforced with 1 1/4" steel angle with 10 carriage bolts per side. This will help keep the sides straight, strengthen the over cab section, provide part of the support for the raised bunk and help with attaching the 'floor' of the over cab section.
The back end will have two modes. The first will use the tail gate and a recycled capper back window to operate in the usual way. This results in an enclosed space utilizing just the 5 foot bed. The roof section overhang is 1 1/2 feet. In the second mode, I'll create a bolt-on (not a slide-out) that will enclosed the area over the tailgate making a 6 1/2 foot floor; long enough to sleep in without going diagonal, which isn't sufficient for a 6 footer anyway. Access to the bunk will be from the inside and from an entrance in the rear fold-up wall if desired. Steps will be required for the latter.
The cab overhang allows for better space above the berth when the top is raised without having to a) raise both end of the roof (a logistics issue) or b) have the raised end ridiculously high. I used trigonometry (actually an online right triangle calculator) to figure out the best compromise between length and height of the overhang and sides. The cab overhang is 12" high and when raised about 3 feet at the back will allow over 18" of space for my feet and much more, of course, for the rest of me. The apparent gap between the cab and the overhang is less than it appears in this image. Parallax again. I'm only going to store lightweight items over the cab; bedding for the most part.
The sides will be vertical (90 degrees) for simplicity of construction and to maximize interior space. The width of the shell will be the same as the width of the bed, including the rails: 60 inches.
The roof will be slightly convex and fabricated from 1/4 inch AC exterior plywood. I want to be sure moisture will shed and for it to be light.
Once I came up with the dimensions, the first problem was finding materials locally that would be exterior grade and long enough to make the sides from one piece of stock. I could get marine grade plywood in 10 foot lengths but shipping/transport was prohibitively expensive. The lumber yard in Breck couldn't provide the sizes I wanted in exterior grade without requiring me to buy a pallet of it, so that was out. I found yard in Denver that stocked 4x8 AC exterior which is great except it is 8 feet long instead of 10, so I resolved to cut off a 12 1/2" section off a 4x8 and scarf 2 feet onto the overhang to make it 10 feet long.
The first cut. I was pretty tentative until I got that done. Lumber isn't cheap. That is a $75 dollar sheet.
After cutting out the rectangle for the cab, I placed a section the 8 foot piece over the overhang section and removed the material from both pieces to create the scarf joint. This picture shows the two pieces clamped together. Basically you create triangle voices that when flipped and matched, result in a joint that is nearly as strong as the original material. By making them at the same time you insure that the angles will match.
The two pieces being dry fit illustrating how they mate up.
The pieces coated with epoxy.
Flipped (with epoxy applied) and clamped. They are clamped onto a 2x12 with pieces going across the top to press the edges of the joint together.
This is the joint after sanding away epoxy that was squeezed out. I deliberately made the scarfed section a bit wider than needed so I could cut the completed side to size. I wanted to be sure the extension was wide enough. Going slightly oversize allowed for small deviations in the fit of the joint to still provide the necessary dimensions.
The completed joints. The panels are rough sized. I still need to trim them to the exact dimensions.
I'll be bolting and gluing 2x3s to the bottom edges of the walls and bulkheads. This will provide the contact between the shell and the truck. Rather than c-clamp hold downs on the rails to hold it in place, I am going to use turnbuckles to the tie down points in the truck bed. The connections to the shell will be bolted on steel straps. I have use a similar method, albeit less beefy, to attach the wood rails I used to mount the artificial rain gutters that I mount a Thule rack onto the bed rails.
The next step is to cut the sides to the desired dimensions which is just trimming the top edge a touch and the bottom edge of the overhang. Then I'll cut the 1/2 inch bulkheads and put dados in the sides to accept them. The sides and bulkheads will be attached to each other with epoxy and steel angles with carriage bolts. The visual effect of the carriage bolts will be interesting, I think. A bit steampunk. The bolts and steel angles will certainly keep things together even if the epoxy fails catastrophically. I don't expect that to happen, but I am of the opinion it is better to overbuild.
I'm hoping to have it fully fabricated by mid September as epoxy and painting will require moderately warm temps to be effective. I'm looking forward to sharing the rest of the project's progress with you and hearing your comments. I'm open to suggestions although I have given this years of thought. Methods of construction are still open to change (the dados were a recent addition, for instance).
I welcome your input.
That said, I do plan to be able to sleep in it for short periods of time without the need to haul the trailer. It is going to be hard sided, although not necessarily insulated. It will have a pop-top a la Westfalia with solid walls that fold up like an A-frame trailer. I'll be able to sleep under the raised roof in a bunk but also on the truck bed floor when stealth is required. When I'm traveling without a trailer, I'll be able to camp in the truck but it will be minimalistic.
Design considerations:
- light weight (relative to an RV slide-in) - it will be about 200 pounds when done. I want to be able to drive to remote locations.
- hold bikes upright with wheels on
- hold a small fleet of skis up to 220 cm
- be able to lie down in and sleep
- fit in garage on the truck - I have 8 foot doors so that wasn't a big challenge, but I need to allow for solar panels on the roof, too. Lengthwise, it will fit with a couple feet to spare. That couple of feet is currently occupied by a workbench, though. When I'm not travelling, I'll be able to remove the bolt-on section (see below), lift the tail gate and walk around behind the truck.
- can be stored in the garage and leave space to park the truck - I will rig a pulley and winch system to lift it up and suspend it from the ceiling
- aerodynamics - I didn't want it wider than the truck to create a smaller head on profile. I'll add some fairing in front of the cab overhang section.
The overhang at the back is no further than the tailgate, 1 1/2 feet beyond the bed; parallax is at play in this image. It is 10 feet long overall. Overall it will be 35 inches tall from truck rail to edge of the roof. The undercut at the rear is deliberate and will give me the walk-around space in the garage when the bolt-on section is removed.
The sides are 3/4" AC exterior plywood, the bulkheads (perpendicular to the sides) will be 1/2 AC exterior. The sides will be reinforced with 1 1/4" steel angle with 10 carriage bolts per side. This will help keep the sides straight, strengthen the over cab section, provide part of the support for the raised bunk and help with attaching the 'floor' of the over cab section.
The back end will have two modes. The first will use the tail gate and a recycled capper back window to operate in the usual way. This results in an enclosed space utilizing just the 5 foot bed. The roof section overhang is 1 1/2 feet. In the second mode, I'll create a bolt-on (not a slide-out) that will enclosed the area over the tailgate making a 6 1/2 foot floor; long enough to sleep in without going diagonal, which isn't sufficient for a 6 footer anyway. Access to the bunk will be from the inside and from an entrance in the rear fold-up wall if desired. Steps will be required for the latter.
The cab overhang allows for better space above the berth when the top is raised without having to a) raise both end of the roof (a logistics issue) or b) have the raised end ridiculously high. I used trigonometry (actually an online right triangle calculator) to figure out the best compromise between length and height of the overhang and sides. The cab overhang is 12" high and when raised about 3 feet at the back will allow over 18" of space for my feet and much more, of course, for the rest of me. The apparent gap between the cab and the overhang is less than it appears in this image. Parallax again. I'm only going to store lightweight items over the cab; bedding for the most part.
The sides will be vertical (90 degrees) for simplicity of construction and to maximize interior space. The width of the shell will be the same as the width of the bed, including the rails: 60 inches.
The roof will be slightly convex and fabricated from 1/4 inch AC exterior plywood. I want to be sure moisture will shed and for it to be light.
Once I came up with the dimensions, the first problem was finding materials locally that would be exterior grade and long enough to make the sides from one piece of stock. I could get marine grade plywood in 10 foot lengths but shipping/transport was prohibitively expensive. The lumber yard in Breck couldn't provide the sizes I wanted in exterior grade without requiring me to buy a pallet of it, so that was out. I found yard in Denver that stocked 4x8 AC exterior which is great except it is 8 feet long instead of 10, so I resolved to cut off a 12 1/2" section off a 4x8 and scarf 2 feet onto the overhang to make it 10 feet long.
The first cut. I was pretty tentative until I got that done. Lumber isn't cheap. That is a $75 dollar sheet.
After cutting out the rectangle for the cab, I placed a section the 8 foot piece over the overhang section and removed the material from both pieces to create the scarf joint. This picture shows the two pieces clamped together. Basically you create triangle voices that when flipped and matched, result in a joint that is nearly as strong as the original material. By making them at the same time you insure that the angles will match.
The two pieces being dry fit illustrating how they mate up.
The pieces coated with epoxy.
Flipped (with epoxy applied) and clamped. They are clamped onto a 2x12 with pieces going across the top to press the edges of the joint together.
This is the joint after sanding away epoxy that was squeezed out. I deliberately made the scarfed section a bit wider than needed so I could cut the completed side to size. I wanted to be sure the extension was wide enough. Going slightly oversize allowed for small deviations in the fit of the joint to still provide the necessary dimensions.
The completed joints. The panels are rough sized. I still need to trim them to the exact dimensions.
I'll be bolting and gluing 2x3s to the bottom edges of the walls and bulkheads. This will provide the contact between the shell and the truck. Rather than c-clamp hold downs on the rails to hold it in place, I am going to use turnbuckles to the tie down points in the truck bed. The connections to the shell will be bolted on steel straps. I have use a similar method, albeit less beefy, to attach the wood rails I used to mount the artificial rain gutters that I mount a Thule rack onto the bed rails.
The next step is to cut the sides to the desired dimensions which is just trimming the top edge a touch and the bottom edge of the overhang. Then I'll cut the 1/2 inch bulkheads and put dados in the sides to accept them. The sides and bulkheads will be attached to each other with epoxy and steel angles with carriage bolts. The visual effect of the carriage bolts will be interesting, I think. A bit steampunk. The bolts and steel angles will certainly keep things together even if the epoxy fails catastrophically. I don't expect that to happen, but I am of the opinion it is better to overbuild.
I'm hoping to have it fully fabricated by mid September as epoxy and painting will require moderately warm temps to be effective. I'm looking forward to sharing the rest of the project's progress with you and hearing your comments. I'm open to suggestions although I have given this years of thought. Methods of construction are still open to change (the dados were a recent addition, for instance).
I welcome your input.
