What does "Light Weight" mean?/

[IdaSHO]

That makes sense. It might not save you a lot on heating if you are keeping it well ventilated, but it will cut down on condensation.

There is that trade-off as well.

And how many MFGs get away with a lack-of insulation. Ventilation.

 

[fluffyprinceton]

Nothing wrong with a massively insulated camper - but the costs are weight & loss of interior space.

Weight because the price of a core material that's both structural & with a high r value is well...high - so you need to use your non structural foam with an internal frame that's never going to be as light as a structural sandwich composite. Interior space gets reduced the thicker the foam you use - which becomes an acute issue when trying to fit a 6'6" bed crossways in a camper while keeping your exterior width to an absolute minimum which I think we can agree is a good thing - particularly trying to design a Tacoma camper with a livable layout - which needs to be a crossways bed if it's a two person rig & you want someplace to stand with the bed in use.

I've got 2" upper walls & roof with an R of 4.5. In my experience that's enough to prevent beading condensation in freezing weather - the question is what's enough & what are the trade offs. The OP's subject is what does "Light Weight Mean?". In the spectrum of weight/cost/building difficulty/insulation your technique/design is an excellent middle ground. It's just not particularly light...Moe

 

[::Squish::]

I know for me, I'm mad at how backwards the current crop of mainstream RV manufactures design and build products.
Solid wood doors, thick heavy construction for the cabinets, and structure along with thick tables and countertops,
Then they save a tiny bit of weight by using plastic sinks and faucets.

Heck even beds are more heavy then they need to be.

I was looking at our range hood the other day and how much extra material it has just for the sake of filling the opening.

There to me looks to be zero thought giving to making anything as light and durable as it could be.

All design and engineering choices are made solely based on ease of manufacturing and cost.

I like a tiny bit of comfort in the woods, but like others here I don't need a living room on wheels,

If the truck camper market wasn't so bad, I'd be tempted to try and build my own. but I suspect that it's one of those
The quickest way to make a million in the Truck Camper market is to start out building them with 2 million dollars.

The market place is ripe for someone to come in and really shake it up, redesigning a truck camper top to bottom
They would do great and sell tens of them.

 

[rruff]

You've gone a middle way in that a panel using XPS foam & ply skins - while lighter - is a long way from using a structural foam with enough compression & shear strength to make a true structural composite panel where the skins carry the majority of the load. I'm not saying your approach is inadequate in any way but it's much heavier than using structural foam - it's also much cheaper & because you are building a structure with a structural internal frame it's a building concept much easier grasp for anyone with typical clad frame house building experience - so it's easy to see the popularity of that approach in the DIY teardrop trailer community - but your really significant weight savings will come only by moving to true structural sandwich composite panels.

There are manufacturers selling structural panels with XPS foam. Total Composites is one. http://totalcomposites.com/panels/ Many people have built airplanes with XPS covered with fiberglass.

Boat builders frown on XPS and use heavier (about twice as dense) and much more expensive PVC or PU foam. The stuff costs ~$300 for a 1" 4x8 sheet, so around 7-8 times as much is higher strength (60 psi) XPS.

I stick in wood stringers just for piece of mind. I don't have time for a research project, and I trust wood to wood bonds more than anything to foam.

 

[UHAULER]

There are composite builders on this site that will build what you want, you just have to pay 10-20k for a empty shell, most people won't.
Like others have said, why spend tons of money on a shell to save 2-400# and then fill it with the same appliances and parts.

Bahn Camper Works is one company who will build what you want.http://www.bahncamperworks.com/

 

[rruff]

you just have to pay 10-20k for a empty shell, most people won't.

The shell on that link is $40k.

 

[UHAULER]

The shell on that link is $40k.

And that's the problem, most people want a lightweight composite shell for cheap, it isn't that easy,if it was everyone would be doing it. I think that is why most DIY camper builders are willing to put up with a little more weight and save tons of money. They may not be the best, but if it works and gets you out camping, that's all that matters.

 

[boxcar1]

I'd have to say that 1000lbs is a good target for a fully outfitted camper (excluding a head )
It can be done using fairly conventional construction methods. I have done it........
As I see it , building with structural panels ( 100% composites ) is just not cost effective and unnecessary at this point.
If the builder can come in at even 1500lbs he will be under the GVRW of any truck worthy of calling an expedition platform.

 

[downhill]

I dont know what you are in such disagreement with. You quoted my entire post, and it contains everything you seem to reciting.

Condensation requires moisture and the proper dew point.

Assuming you are using zero methods to get rid of the moisture, all you can work with is the dew point.

Dew point is the temperature at which the moisture in the air visibly forms into liquid.


My simple point is that by increasing the insulation value, you will reduce the chance of even getting to that dew point.

Is this incorrect??


Also, I never said air exchange wasnt needed. I thought I made that very clear. You even quoted it.

What I did say is that in many cases it isnt. How often do you open the door? How long do you stay within the cabin without leaving?

Even in North Idaho winters, we are rarely in our camper for more than 10 hrs without opening the door or hatch.

In my experience, simply opening the door for a brief period is enough to exchange plenty of air.

In sub zero temps, with a well insulated camper, 2-people, two dogs, for weeks at a time, we have zero condensation issues. A bit forms on the window frames, but that's it.

I guess I am confused...When you said "Air exchange helps, but in many cases it simply isn't needed if insulated well",...I took that to mean " Air exchange isn't needed if the insulation is good enough???

In terms of air temperature, dew point, etc., the point I was making was that the wall insulation and the interior temp do not negate condensation caused by cold bridging. You can have 4" of insulation in the walls and the windows will still collect condensation. That is also true of any cold bridged aluminum. By "cold bridged" I mean aluminum framework that extends from the outside to the interior space. The ambient air temp can be above the dew point, but the cold surfaces can be way below that.

In terms of time without doors open, if you sleep through the night then we are talking 8 hours or more. Once everything you have is damp, opening the door for a few minutes will not dry it out. Small spaces need constant ventilation to keep that humidity down, and to provide good air quality. That air exchange becomes a primary driver in determining thermal efficiency.

You can make a wall as thick as you like, but there definitely is a price to pay in terms of weight. It may feel light when you pick up a little piece, but the cumulative weight of adding another 1/2" of thickness can be well over 100 - 150 pounds. If that 100+ pounds really made a difference, then OK, but I don't see how it would.

 

[simple]

Light weight could mean not building a kitchen with granite counter tops! LOL.The term "Light" and "Light Weight" has been so thoroughly played out in the RV industry via marketing it doesn't really apply to what the OP is driving at. I think the OP has defined it fairly well with weight specs. Within those specs, designs will also be sans ovens, TV's, AC etc. I think what its coming down to is a cultural division between getting further out with a minimal setup possibly beyond the range of any vehicle as apposed to pulling into a parking lot or turnout.

 

[rruff]

I took that to mean " Air exchange isn't needed if the insulation is good enough???

Sorry to butt into your argument, but I thought he meant that air exchange expressly to reduce internal humidity was unnecessary. You still need some fresh air for breathing.

 

[downhill]

And that's the problem, most people want a lightweight composite shell for cheap, it isn't that easy,if it was everyone would be doing it. I think that is why most DIY camper builders are willing to put up with a little more weight and save tons of money. They may not be the best, but if it works and gets you out camping, that's all that matters.

The price of campers has skyrocketed. In many cases the cost of the camper is more than the truck. I think people are mostly good with paying a fair price, but at $40,000, ......do you buy a camper or build a big new workshop?? When I was searching for a possible camper, I couldn't find anything at any price that suited my needs. The problem really, is that there needs to be a sea change in the way campers are perceived and built. In the boat and plane world for instance, there is a focus on performance. In the camper world it seems to be a focus on features and appointments. There are some great options out there for those who are fine with maxing out their GVW for space and comfort. Nothing wrong with that at all. The guys like me who want a truly light performance shell, it's pretty much a wastelend.

 

[downhill]

Sorry to butt into your argument, but I thought he meant that air exchange expressly to reduce internal humidity was unnecessary. You still need some fresh air for breathing.

I understand, but I do not agree. Air exchange in my opinion IS EXPRESSLY NEEDED TO REDUCE HUMIDITY.

 

[downhill]

Light weight could mean not building a kitchen with granite counter tops! LOL.The term "Light" and "Light Weight" has been so thoroughly played out in the RV industry via marketing it doesn't really apply to what the OP is driving at. I think the OP has defined it fairly well with weight specs. Within those specs, designs will also be sans ovens, TV's, AC etc. I think what its coming down to is a cultural division between getting further out with a minimal setup possibly beyond the range of any vehicle as apposed to pulling into a parking lot or turnout.

There clearly is a cultural difference. I've been a backpacker my whole life. Many people I know have never been more than 100 feet from their car. I'm making ZERO value judgement about that! My point is that MY needs are not being served by anything currently on the market. Starting this thread was intended to look for kindred souls,...if indeed any existed

 

[rruff]

And that's the problem, most people want a lightweight composite shell for cheap, it isn't that easy,if it was everyone would be doing it. I think that is why most DIY camper builders are willing to put up with a little more weight and save tons of money. They may not be the best, but if it works and gets you out camping, that's all that matters.

The Bahn camper shell weighs 700lb and it sounds like they add framing and insulation on top of that. http://www.bahncamperworks.com/products/shells
Maybe they are doing a thin sandwich with structural PVC or PU foam, then adding a layer of XPS inside for better insulation. At any rate it isn't that light.

I just added up a material list for mine and it comes to 600lb for the shell (excluding windows, hinges, latches, etc) and it mounts directly to the frame, so I lose the weight of the truck bed too. You could certainly argue that the Bahn is heavier duty, but I've built a camper like this before and it was durable enough for me and I had no issues with it.