DIY Over-Cab Camper build help...Not an in-progress build (YET)

[teelong83]

Hey everyone. I am new to this forum, found this site in my never-ending research leading up to doing my own camper build. Skip to the 2nd paragraph if you don't want to read about me or what I am trying to do. I have a 2003 Chevy 1500 Z71, I bought new, and have taken care of. No mechanical issues, but still original parts/suspension, so weight is a concern. I am wanting to build something that will sleep 3 adults, possibly 4 adults, and it's primary use will be camping with my wife and son, but also used for a hunting/fishing base camp. I live in south Alabama, temps range from high 20's in winter to high 90's in summer...actually they happen in the same week most of the time, but c'est la vie.

I am wanting to build a slide-in camper but also keep it to somewhat of a budget. Not trying to do it all for $100, but I also don't want to afford a $30,000 camper, thus my predicament. I have been eyeing using the xps foam from HD/Lowes, and have seen some builds where guys use the foam sheets exclusively and then fiberglass them together, (my concern with this is obviously the structural integrity of driving/high winds/something falling on it). Others have used the 2x2 strips and framed it out then used the foam for insulation and skinned with a plethora of materials. Only using the foam sheets appeals to me due to the weight saving, and I was thinking if I were to use a spray-on bedliner material around the entire camper, I believe that would be sufficient for holding it together (maybe add a single layer of 10oz or so fiberglass prior to the bedliner). If anyone here has done the foam only build, how is it holding up and would you do anything different?

Please, let me hear your suggestions, concerns, insights, etc. I can take it all, you won't hurt my feelings. Thanks in advance for your replies and I look forward to taking you guys along on my build.

 

[mobile007]

I've been a lurker here for years, and I am in the same boat. I am planning to build an over cab camper for my 2007 F150 XLT 4.6L CrewCab. I have also been curious about using the foam from Lowes/HD. Because I live in Canada, I am also interested in building a 4 season camper. I will be keenly following your build.

 

[teelong83]

I've been a lurker here for years, and I am in the same boat. I am planning to build an over cab camper for my 2007 F150 XLT 4.6L CrewCab. I have also been curious about using the foam from Lowes/HD. Because I live in Canada, I am also interested in building a 4 season camper. I will be keenly following your build.

Mobile007, I know that the foam construction is viable...I have seen teardrops, trailer builds, and also cabover's done in the foam...I just haven't seen any long term use updates. Most I have seen do a 6 months or 3 week timeline. As I tell my wife, "Hang on, it's going to be fun".

 

[pith helmet]

I am also in the dreaming stage of a 1/2 ton over cab build. I will be interested to see what kind of info you get here. Welcome!

 

[pith helmet]

I wouldn’t be comfortable with any foam sheet material I am familiar with as structural, even with fiberglass.

 

[simple]

I haven't built one of these but I'd be concerned about pure foam construction being able to handle the weight of a couple people in the cabover part. I could see it possibly working for a smaller box or high roof bed topper. How long is your truck's bed?

 

[mobile007]

Mobile007, I know that the foam construction is viable...I have seen teardrops, trailer builds, and also cabover's done in the foam...I just haven't seen any long term use updates. Most I have seen do a 6 months or 3 week timeline. As I tell my wife, "Hang on, it's going to be fun".

Yes, good point. I would love to see long term viability, in years.

 

[billiebob]

I think building a box or teardrop out of taped foam boards is pretty straight forward but adding the cab over cantilever dramatically changes the engineering and load dynamics requiring some sort of structural frame. IdaSho has likely built far more than you want, but taken at scale you need to incorporate most of how he built his overlander..... just scaled down.

 

[Peter_n_Margaret]

1.5mm of fibreglass over 16mm of closed cell polyurethane foam.
17 years and counting.


And another. Driven from Australia to Scotland and back, via Mongolia, Russia, Tibet, India.....

Both are DIY builds.
There is no better material to build expedition vehicles, in my view.
Cheers,
Peter
OKA196 motorhome

 

[mobile007]

I think building a box or teardrop out of taped foam boards is pretty straight forward but adding the cab over cantilever dramatically changes the engineering and load dynamics requiring some sort of structural frame. IdaSho has likely built far more than you want, but taken at scale you need to incorporate most of how he built his overlander..... just scaled down.

I recall a truck camper build thread by @pods8 a few years ago in which he used a combination of foam, fiberglass and wood in his construction (https://expeditionportal.com/forum/...-pop-up-camper-build-thread.58926/post-901823).

Would still be interesting to see how @teelong83 tackles structural and weight handling issues in his build.

 

[teelong83]

@Peter_n_Margaret
Is the first two videos yours? I see the angled uprights at the corners of the cab going to the (what I am assuming) sleeper. Was this for any purpose other than structural for the sleeper? Do you have a metal frame on the bottom for the sleeper?

 

[Peter_n_Margaret]

@Peter_n_Margaret
Is the first two videos yours? I see the angled uprights at the corners of the cab going to the (what I am assuming) sleeper. Was this for any purpose other than structural for the sleeper? Do you have a metal frame on the bottom for the sleeper?

Yes, both videos are mine.
The uprights from cab to bed-over are purely for scrub protection. Otherwise branches get stuck in the corner.

There is a light weight steel frame inside, but It is totally unnecessary. I am currently constructing another similar vehicle and it will have no steel.
Cheers,
Peter
OKA196 motorhome

 

[teelong83]

Just to be clear, I am not morally opposed to using materials in conjunction with the foam. I don't think that 2x2 framework in certain areas would add that much weight, but would add some integrity to the build. I have also considered aluminum, but aluminum is it's own animal, and I don't have the equipment to weld aluminum and rivets have always caused me to invent new words. I have been giving this some thought, and 1 option I have considered is running 2 "beams" essentially from the back of the camper to the front, and then across the front to tie them together. These beams would be either wood 2x2's or maybe aluminum tube or i-beam. I will also have some sort of beams or bracing on the 4 corners of the main body for jacks.

 

[dbhost]

I am doing something similar although I am still working design issues out, but have opted to go with an aluminum hi roof walk in contractor cap.

Being that you are working with a 1/2 ton truck, weight is going to be a BIG issue for you. Keep it in mind. Foamie contstruction is light, honestly aluminum framing would be lighter, stronger, and eliminate the chances for rot that wood framing would introduce, but if you insist on wood, go to tnttt.com and look up the foamie sub forum, there are articles on waterproofing your wood.

You will likely want to brace each corner, and honestly for the main rib like you show that includes the overcab, you may want to use 2x4 not 2x2, to take the forces applied to the cantilevered bad area.

XPS foam is a popular sandwich component for composite panels / builds, but be careful of EPS or XPS foam and Polyester fiberglass resin. The resin will eat the foam. It will cost more, but pony up for Epoxy resin. You get the added benefit of it not stinking to high heaven for years after the build!

The other, more popular option with foam though, is known as Poor Mans Fiberglass, or PMF for short. Basically you use light canvas drop cloths, OR thrift store bed sheets, the flat sheet not the fitted kind, as the "fiberglass cloth" and either PPG Gripper primer / sealer, OR Titebond 2 wood glue that has been reduced, the ratio evades me, as the "resin", method of laying is more or less the same as actual fiberglass.

To give you an idea of strenth. I tool and glued up using Gorilla Glue, a 4x4x24" beam of XPS, did 3 layers of PMF using bed sheet fabric and let it cure for a week. Then stood it on cinder blocks. and then stood on it.

I am NOT light at 350lbs.

It took my weight, it did dent sure, but it did NOT crack of otherwise catastrophically fail.

I was thinking anywhere weighty objects are attached I.E. Window UNT AC pass through should b framed with wood, door openings, main rib where you would attach an awning etc...

 

[rruff]

I have been eyeing using the eps foam from HD/Lowes, and have seen some builds where guys use the foam sheets exclusively and then fiberglass them together, (my concern with this is obviously the structural integrity of driving/high winds/something falling on it). Others have used the 2x2 strips and framed it out then used the foam for insulation and skinned with a plethora of materials. Only using the foam sheets appeals to me due to the weight saving, and I was thinking if I were to use a spray-on bedliner material around the entire camper, I believe that would be sufficient for holding it together (maybe add a single layer of 10oz or so fiberglass prior to the bedliner). If anyone here has done the foam only build, how is it holding up and would you do anything different?

Foam only?! Foam is a core material... good insulation and good for structural panels. I don't think bedliner over foam is going to help much. Fiberglass over the foam is definitely viable, though.

I'm building a camper now with PVC foam core and wet-laid fiberglass and carbon skins. I built a couple in the past with cheap XPS and wood slats in the core, and 2.7mm Luan ply skins; the later one encapsulated with a layer of fiberglass. I kinda favor that method. It's simpler DIY, not as messy, quite light, the embedded wood gives you lots of hard points, and it's cheap. Idasho had a great build thread using that method (only with 6mm Meranti ply), but that thread seems to be missing.

Sanding fiberglass... sucks. My garage is covered in a thick layer of nasty dust, and it gets everywhere.

There are many examples of DIY foam core + fiberglass sheet for skins. Similar to what Total Composites does. That would be a very viable method.

If you use wood in the core, use it sparingly. It's important to think "stressed skin panel" construction, not like a stick built home. It can be done light so long as you use strong materials and glue.

I put this together awhile back to estimate panel weights and cost. Ask questions!