How to make a good camper shell?

[windsock]

So my thoughts on a good camper shell have been changing and evolving.

First I started with a steel and aluminium frame and was eager to cover it with aluminium sheet. But I resigned because of the weight of steel, the lack of flexibility of aluminium and because of the softness and weight of aluminium sheets (aluminium doesn't bounce back so every hit by a branch leaves a dent). Oh I forgot to mention that sticking together alu sheets is not so elegant and prone to create leaks. Plus it would cost me a lot of Sikaflex. In other words a metal cage covered in alu is a dumb idea, although the easiest to make.

I for one am puzzled by the logic you have used to write off the aluminium and steel as a dumb idea. I'll note my experience for what it is worth. I lived (vs camping temporarily) in aluminium clad, steel or aluminium framed campers for many years (quite a few years ago now) and don't see the logic of your discussion playing out in reality.

All other materials you have discussed could theoretically be damaged to some degree by the same sort of impact you mention that could damage an aluminium panel. You can buy different tensile strengths of aluminium panel and so you can design to minimise damage from impacts. Auminium can be patched easy (in the field or workshop although cosmetics suffer somewhat), is easy to construct and can be easily joined. Like any construction method, it should be based on good design around the materials used. You indicate the cost of sikaflex as an issue but then mention using it to also join other materials. All other methods you have indicated above have their issues either with construction duration, field repair or cosmetically over time. I have seen professionally constructed fibreglass cracking and 'crazing' after a few years. I have seen stone chips take out chunks of glass resin. I guess new space-age materials allow for a bit more impact resistence etc but every material out there will be prone to various issues on overlanding vehicles if used as intended. The side of my land rover is a testament to the ability of alumimium to withstand impacts. Sure it shows creases and dents but this is from 26 years of general farm use and offroading. Any other material would also have been damaged under the impacts inflicted.

Weight can be an issue if design is poor. If I did it all again I would use high-risk impact zones and weather tightness (sheet seam location) as the two design-related factors in deciding framing positions and the thickness (and therefore the weight) of the steel or aluminium wall of the framing material. All other areas of cladding not supported directly with structural framing would be supported by interior constructions for seats, storage and shelving that would be in there no matter what the exterior cladding. If you treat the design of the frame thus you can minimise the framing required and don't end up with something looking like a house frame. I would also use the logic that the carrier-vehicle was prone to impact damage and could be repaired so why not design the camper along the same lines instead of aiming for a bullet-proof panic-room type of safe room. Things get damaged out there, be able to fix it in the field and drive on. The ability to effect a simple field repair and to drive a camper designed for the purpose of providing shelter from the storms is what I liked about what I had and would be seeking to replicate if building today.

Flexibility can be included in the design or can be excluded as required. Aluminium can 'warp' to take up flexing whereas I see other construction methods and materials could also have problems if not designed for. If flexibilityis excessive then the seams can be under stress and again, good design is your friend.

One problem that I had that you don't mention is thermal bridging. This was an issue that I found in my house trucks and buses over the years when in very cold environments. It can be designed out if careful consideration is given.

Would I camp in the same sort of thing these days? Difficult to say. In all honesty, for ease of construction and durability in the environment I drive into for my current camping, most likely yes. As in all cases related to individual choice, your mileage may vary.

I am not saying don't build with anything else but aluminium cladding and steel or aluminium framing. What I am trying to say is don't write off aluminium as a building material for the reasons you have given.

I look forward to continued discussion and wish you all the best in your eventual choices and ensuing camping/overlanding.

[Ndmker]

Windsock, the problems with aluminium are numerous. I am an alu lover as I've spent most of my childhood on mountain bikes (downhill/freeride) and simply love the material, but...

But I had to give up my favorite metal because it doesn't seem to fit the purpose.

1. Weight- no matter how thin is your alu sheet, it will weigh more than fiberglass.
2. Yes, I forgot about thermal bridging.
3. We also need to add condensation, which means humidity, which means corrosion of other metals like steel or fungus on fabrics
4. Aluminium is harder to stick together than fiberglass. I have a TIG welder and like working with alu, but in spite of that I consider alu troublesome.
5. The ease of on-trail repair doesn't convince me. I is easier to unroll a bit of fiberglass mat, soak it in resin and patch a hole, than carry alu sheet, metal scissors and play with rivets or sikaflex.
6. I also heard that alu can't directly stick to steel due to corrosion.
7. Another problem is shaping aluminium. It is hard to create an aerodynamic shape or rounded corners. I would need to have an English wheel for that. Yes, free form shapes can be achieved by stitching together various small pieces of alu sheet but I don't want a camper that looks like an armadillo.
8. Oh and I forgot about aluminium maintenance. The elements can create aluminium corrosion so I would need either to paint the camper or polish it from time to time, while the fiberglass gelcoat is just a ready to use surface.


Maybe I could live with all those problems but point no.1 is vital, which is weight. Light weight means better fuel economy, less strain on the frame, shorter braking distance, less risk of tipping over etc. Sometimes a difference of 200-500kg means that either you pass over that wooden bridge or fall into the river. The fact that a 4.5L gasoline engine can handle 6 tons easily is not an argument.

The assumption here is that you would be using two layers of relatively light plywood, separated by insulation of some sort. The structure would gain its strength from its complexity, not from the raw strength of any one panel. Those who work with metal frames and various plastic panels work the other way - the panels add no strength.
Thus, if you do it right, each window, etc., would actually serve as a reinforcement of the panel structure and reduce the number of ribs required. Similarly, any place a cabinet joins the wall, the cabinet framing replaces a rib. Watch the videos on Shachagra and you will get the idea. Probably the only place you would need to use heavy plywood would be the floor, and even here, I use a double structure with insulation. (And a few ribs.)
Good luck!

DiploStrat, I understand the idea behind a sandwich structure but it is still overbuilt. Let's count all the layers

- external fiberglass and resin to protect the wood
- plywood
- XPS or other insulation
- plywood
- internal fiberglass and resin to protect the wood
- a fabric or other interior finish

Problem 1- Whenever I drill a hole I compromise the structure by exposing the wood to the elements so I need to isolate every drilled hole
Problem 2- where do I route the tubing or cables? I would need to create some external channels which robs me space and is not elegant. Yes, I can route stuff in between plywood panels but this would be a problem if anything breaks: ripping a cable or pipe from the wall would be like destroying the whole camper wall.

My idea is to make the build more user-friendly, though definitely not builder-friendly

- fiberglass wall with reinforcement ribs made of wood blocks or strips of waterproof plywood.
- in between the ribs I put XPS panels as isolation
- interior 'cozy' layer like thin 4mm kapok plywood (almost 3x lighter than pine) covered with nice fabric (I used alcantara for my previous camper).


Below is a diagram. My idea is also to make a sandwich structure but with removable inner wall for cable routing etc.

wall-exploded-view.jpg

[pods8]

while the fiberglass gelcoat is just a ready to use surface.

Do you have a mold to make this camper shell in? Otherwise you won't be gel coating since the way that is normally done is to lay down the gel coat and then the fiberglass. If you don't have a mold then you'll still be painting.

DiploStrat, I understand the idea behind a sandwich structure but it is still overbuilt. Let's count all the layers

- external fiberglass and resin to protect the wood
- plywood
- XPS or other insulation
- plywood
- internal fiberglass and resin to protect the wood
- a fabric or other interior finish

There doesn't need to be plywood layers in there unless you design it that way.

Problem 2- where do I route the tubing or cables? I would need to create some external channels which robs me space and is not elegant. Yes, I can route stuff in between plywood panels but this would be a problem if anything breaks: ripping a cable or pipe from the wall would be like destroying the whole camper wall.

If you're planning to use kapok on the inside anyways your main shell could still be a glass-foam-glass sandwich and then just offset the plywood on raised strips so you can chase wires behind it. Only reason I'm saying towards the sandwich is you mentioned weight above, I'd bet you'll use less fiberglass/resin doing a sandwich as opposed to trying to do a single skin and ribs (not to mention working glass down around each rib would be slow compared to a flat layer that would be the interior of the sandwich).

Personally I'm just painting my interior walls and wiring conduit will be embedded in some key locations in my roof, most the wiring in the lower camper will be inside cabinets/trim pieces. IF it ever came up I missed something I'd surface mount some conduit or trim but hopefully proper planning will address most future needs.

[jronwood]

I was stationed in Hawaii some 25 years ago and watched a guy in the military moral support wood shop build and wood and fiberglass a truck cap. When my ETS came up several month later I went home and in my Mom's garage with only a few rudimentary tools did the same. A little heavy but it was EASY and it came out great. Dont worry about the wood, if it were a full blown RV, well OK good arguement, but it is a smallish unit.



Jronwood

[URY914]

I guess Airstream has been getting it wrong all these years.

[Ozarker]

I might suggest you visit the "Wood Boat" forums. Many wood boat builds are detailed in construction methods and apply to these structures as well The furniture is a structural part of most small boats. Building a camper is alot like building a boat, both are designed to keep water out, tips such as weeping holes in framing apply too allowing what water or condensation does get in to dry or drain.

[Dale]

I plan on making my cap/camper from Nyloboard. Its made from recycled carpet and you can get it sandwiched in fiberglass. comes in 4'x8' sheets (or custom) 3/8, 1/2, 3/4 and 1". sandwich 2" rigid foam in between to make SIP panels. I should be starting within next month, I am a building contractor so I like the fact I can use my tools.

[Thomcat]

Well, it's not a "camper shell", but it's freakin' light and has over 10K miles under it so far....

http://www.tnttt.com/viewtopic.php?t=44293

This is the build journal for my fiberglass/epoxy/honeycomb composite teardrop trailer. Pay special attention to the later ramblings where I discuss what I would have done differently. In the meantime I've built a second one which has racked up ca. 6K miles. Neither has had any real issues.

Hope this helps!

Whitney

[adam88]

The best option for building a camper is the one you will actually do. Your idea sounds amazing, but it also sounds like a lot of work. That's not a challenge, just an observation. Best of luck.

[LivelyZach]

Several years ago ,I built a TTT(tiny travel trailer) think teardrop in size 4 ft x 8 ft,making it as lightweight as possible was the goal.My framework was built utilizing PVC pipe .The basic idea was a success ,the finished product weighed half as much as a similar design in wood ,though I used PVC sheets for the wall sheathing...not taking into account eventual degradation from exposure to sunlight..The framework is still intact ,though the sheathing is long gone.Its now used as a cold frame sheathed with clear vinyl .My point being that perhaps you might consider a framework similar to the one I constructed way back then ,utilizing other materials for outside sheathing instead.