Foamie Hard Shell Roof-Top Tent?

[TPA5]

My wife and I have been looking at roof-top tents lately, so we can sleep off the ground in an easy to set up system without towing a trailer. We've been looking at stuff like this:

tent3.jpg (164.64 KiB) Viewed 2077 times

tent2.jpg (125.58 KiB) Viewed 2077 times

tent1.jpg (68.87 KiB) Viewed 2077 times

Thing is, hard-shell roof tents like that are fiendishly expensive. So the other day a brain-wave hits me, why not build one foamie style? I figure if foamies can withstand the rigors of being turned into teardrops, squaredrops, and even baby Airstreams surely it could withstand being the top and bottom shell for a roof-top tent. Plus it would be worlds cheaper than buying a $4,500 manufactured one.

I've been mentally pondering different ways to do it, so I figured I would ask the foam-gurus here what they think of the idea. The shell itself I imagine would be easy, it really is almost like building a very shallow box for the top and bottom, and skinning it in canvas. I'm not sure however of things like attaching some kind of lift system to the foam, and how I would attach tent canvas to the top and bottom shells? And, would it need some kind of wood reinforcement? Finally I would need to decide on how to secure it to a roof-rack. Still, I think it can be done and I don't think it should be overly difficult?

For weather-sealing I'd just go simple and make the top larger than the bottom, so it could slide over the bottom. Then just have some rubber weather strip in the gap and I imagine that should do the trick when closed.

The basic dimensions I'd be looking at are 79″ x 55″ x 36″ (when open). Those are dimensions that seem to be common on manufactured roof top tents.

What are your thoughts? Think something like this could work in a foamie style? I figure we'd probably be the first to try something like this, so it could be quite fun.


Cheers!

[ghcoe]

Well I have been thinking of one too. Not sure when I will get a chance to give it a try so I will shoot you the idea.

Car top

Car Top.png (42.46 KiB) Viewed 2056 times

The idea here is a double lift so that you do not have to worry about a complicated lifting device. First you would lift the main, which hinges in the front. Then you would get inside and lift the secondary roof, Which hinges at the back. This would give you good headroom for day use and a nice sleeper for evening. The floor would be just OSB the rest foam and canvas.

Yes, I think it is quite doable. And looking forward to your take on roof top campers....

[TPA5]

Well I have been thinking of one too. Not sure when I will get a chance to give it a try so I will shoot you the idea.

The idea here is a double lift so that you do not have to worry about a complicated lifting device. First you would lift the main, which hinges in the front. Then you would get inside and lift the secondary roof, Which hinges at the back. This would give you good headroom for day use and a nice sleeper for evening. The floor would be just OSB the rest foam and canvas.

Yes, I think it is quite doable. And looking forward to your take on roof top campers....

That drawing looks great, I really like the idea of having the additional pop-up for even more headspace in the tent. It would certainly make changing clothes in the tent a sight easier. Were you thinking of using more canvas for the second pop-up, or were you thinking possibly making the sides out of foam? Also, what do you think would be a good hinge system for the front?

Thanks for the reply!

[ghcoe]

That drawing looks great, I really like the idea of having the additional pop-up for even more headspace in the tent. It would certainly make changing clothes in the tent a sight easier. Were you thinking of using more canvas for the second pop-up, or were you thinking possibly making the sides out of foam? Also, what do you think would be a good hinge system for the front?

Thanks for the reply!

It has been sometime since I drew up this design. I remember originally thinking of hard sides for the bottom and top, but had issues with the fold over of the walls. I think canvas would probably be the way to go for simplicity now. I though I had more/better drawings, but I could not find them.

Just a piano style hinge for the front with a canvas covering would probably work just fine like I did with my galley hinge on my build, about half way down http://tnttt.com/viewtopic.php?f=55&t=54099&start=585 .

[OP827]

It is a good idea, I am subscribed and will watch this design to unfold. How about a whole thing made of foam including folding walls? Very simple folding box with basic weatherstrips on the sides. Foam and ply sandwich for bottom part to make it strong and rigid, some streamlining of the roof cover front.. This should not be too difficult to build.

[fotooutdoors]

It is a good idea, I am subscribed and will watch this design to unfold. How about a whole thing made of foam including folding walls? Very simple folding box with basic weatherstrips on the sides. Foam and ply sandwich for bottom part to make it strong and rigid, some streamlining of the roof cover front.. This should not be too difficult to build.

For fuel efficiency, streamlining of the back is also important, FYI. It may be more so than the front, though that depends on airflow properties at the nose and how close it sits to the roof.

Sent on my phone. Pardon the autocorrect.

[OP827]

My biggest concern with this particular idea is a car roof rack load capacity though... I am thinking that with just two adults weight w/o anything would seriously overload it, or I am wrong?

[ghcoe]

My biggest concern with this particular idea is a car roof rack load capacity though... I am thinking that with just two adults weight w/o anything would seriously overload it, or I am wrong?

In most cases you will find that the manufactures, stock and after market, roof rack systems max rating is 150lbs. I am sure that that is for liability reasons. In theory if you put two systems on board you should be able to haul 300lbs and so on, but the max roof top rating is 150lbs. What is the stationary weight limit would be a better question for this application. A sheet of OSB, foam, canvas, bedding and a few camp items should not push over 150lbs. 2 people would of course make a big difference in limits.

[QueticoBill]

I'm pretty sure the weight limits are based on the car in motion, and in particular roll over on cornering. Did find a quip where two Thule engineers loaded up one of their carriers with 2000 pounds and drove it at 50 mph - without failure. It would be nice to keep this in the 150 pound range closed and a little aerodynamic - especially avoiding lift - but seems pretty safe.

[ghcoe]

4x8x7/16" OSB is about 50 lbs. 4'x8'x2" foam is about 10lbs. Plenty of room.

[OP827]

Load capacity would also depend on a car roof design. I feel that the Factory-Installed Flush Side Rails seem to be more suitable for this application, as better brackets (continuous or multiple) can be fitted then for weigh distribution and less stress concentration. My Pathfinder SUV has raised rails attached at two points, front and back, which creates stress concentration points to the roof sheet metal (which does not feel very strong).

Source - https://www.etrailer.com/faq-roof-racks.aspx

[QueticoBill]

I see madcamp is apparently out of business. At the price, probably didn't sell many.

Happened on this for mid $600s: https://goo.gl/XvIcM5 (REI has it for mid $900s)

[OP827]

I see madcamp is apparently out of business. At the price, probably didn't sell many.

Happened on this for mid $600s: https://goo.gl/XvIcM5 (REI has it for mid $900s)

It could be challenging to home make it at that price here. Large production in Asia making roof tents in large numbers, some are with wireless remote control to open. Different design though, it's basically a tent on the car roof platform, no hard top. I was thinking towards hard wall foam sandwich design that has a much better insulation.

[OP827]

Came across a good review video for roof tents - https://www.youtube.com/watch?v=-R6B4wT5hnI

[QueticoBill]

I am not certain that with fabric sides the foam up top makes much difference as far as insulation, do you? Now, a fold up shelter with foamie walls - maybe. The wedge shape - hinge top to bottom at front - and make sides each two long triangles that fold into center - use heavy canvas for "hinges" - might work. I'd be inclined to hang something like a couple of quilts overlapping at rear rather than another hard side with door - but possible.

I guess since I go winter camping - plain tent, no stove, up to -20 F - I'm less concerned about insulation. Hot weather camping might change my mind.