Teardrops n Tiny Travel Trailers

gizmotron wrote:OK now, I changed the framing to 1/4" stringers for studs that support the 1/4" rafter/stringers. All that framing sandwiched between 2" foam. With 2 layers of 6oz fiberglass and Epoxy, the estimated weight comes down to 770lbs. That makes it the strongest and it also allows for the entire inside done in 1/8" Luan plywood.

See if I understand correctly... your 2" foam has 1/4" ply strips going through it top to bottom (on the camper sides) and side to side (on the camper top). All the way through (basically cutting the foam into sections)? What is the spacing?

And how are the other 1/4" pieces arranged?

rruff wrote: See if I understand correctly... your 2" foam has 1/4" ply strips going through it top to bottom (on the camper sides) and side to side (on the camper top). All the way through (basically cutting the foam into sections)? What is the spacing?

And how are the other 1/4" pieces arranged?

The Owens Corning extruded polystyrene snaps the long way at 16 inches. So I will be running the insulation between the 16" gaps made by stud and rafter strips. At the top of the roof, at the roof line edge, along the sides, will be a single embedded 1/4 " by 8" wide piece running down each side of the trailer. This is to set the hard points needed for the solar panel rail on top. The entire front will be made of an elaborate 1/4" fusion of plywood that is too complicated to describe. It will serve the function of creating a curved front that sticks forwards 24" at the center, about 38" above the floor. The front is curved like many modern trailers, from bottom to top, with a square back and square sides. Heck with the retro ham. I want a power plant on the roof. There's room enough up there for four 180 watt solar panels that can be tilted up for better efficiency. That's 720 watts at peak power. Add light weight lithium batteries and you are styling at Quartzsite AZ.

OK, the 1/4" stringers embedded in the 2" foam is out. I found something better. One of the Foamie builders used strips of fiberglass and epoxy to strengthen all the seams and joints before laying up a single layer of 10 oz canvas and Titebond II to install it and Gripper Primer paint to fill it before a final paint job. This sounds like the lightest and best way to do it, and to make it strong. My solar panel mounts are only 4 inches inside the edge of the inner roof. That will be strong enough to hold the panels. So no stringers in the roof either. No studs too. There will just be fir outs for windows and the door. All joints and embedded trimmers will be glued using epoxy also. Now my weight estimate comes in at 650 lbs Dry/Empty. That's without the 150 lbs for the three solar panels and two lithium batteries. Completed it will weigh about 800 lbs. Now I'm pretty sure that the epoxy & glass strips is the best method for joining foam.

Not to be argumentative ,but the use of epoxy as an adhesive , might not be any better than Gorilla glue , TB2b, or other glues ... The Foam always fails before the glue fails ... Likely you could use a waterproof library paste to hold everything together , the tight outer skin does all the real work ... for bracing the foam for load bearing ( as on a roof), some imbedded full span side to side plywood strips installed perpendicular to the foam would be better from an engineering standpoint ... simple to do ... cheap and sturdy ...

Ps. we used strips of fiberglass tape secured with TB2 on Foamie #1 seams and edges ( as “reinforcing strips” ) and there was never a problem ... Now still working for Bonnie ...

That's interesting. Using fiberglass strips with TB2. I'm going to look for polyester strips. It's what they use for the core of vinyl coated polyester. It's less likely to fray if I have to cut strips. It's stronger than cotton canvas. If I were to cover the roof stringers with fabric strips and TB2 before skinning it that would be better too. I didn't like the idea of keeping the embedded stringers attached only to the foam where they touch and nothing else. It only adds 15 lbs to include stud & rafter stringers embedded in the foam, ... and a heck of a lot more work.

I found it. They make polyester canvas in 14.5 oz.

"Polyester canvas tarp fabrics are more than twice as strong as regular cotton canvas tarp fabrics. Fabric Weight: 14.5 oz / sq. yard. Silicone treated polyester canvas is water resistant. Colors available: Black, Blue, Gray, Olive Green, Tan, White." Less than $ 7.50 per lineal yard of 60" wide. Cheaper than that if you buy it in 25 yard rolls.

http://www.mytarp.com/polyester-canvas-fabrics.aspx

This stuff is cool. It won't shrink like cotton does. It's way cheaper than fiberglass fabric. You can cut it into strips without it having the fraying issues that fiberglass cut strips would have.

gizmotron wrote:I found it. They make polyester canvas in 14.5 oz.

"Polyester canvas tarp fabrics are more than twice as strong as regular cotton canvas tarp fabrics. Fabric Weight: 14.5 oz / sq. yard. Silicone treated polyester canvas is water resistant. Colors available: Black, Blue, Gray, Olive Green, Tan, White." Less than $ 7.50 per lineal yard of 60" wide. Cheaper than that if you buy it in 25 yard rolls.

http://www.mytarp.com/polyester-canvas-fabrics.aspx

This stuff is cool. It won't shrink like cotton does. It's way cheaper than fiberglass fabric. You can cut it into strips without it having the fraying issues that fiberglass cut strips would have.

Silicon embedded and water resistant. Means tb2 and paint will not bond to it.

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Fiberglass fabric strips are water resistant too. I should get a sample and test it first. That silicone is just a spray on treatment. It still allows the glue to flow into the nooks and crannies of the fabric, where it creates a strata layer formed by dimensional imperfections. It's the dry glue in the weave that does the sticking. Same is true of the fiberglass.

I'm pretty sure when GPW says he used fiberglass tape, he is referring to drywall joint tape with a very open mesh, as opposed to laminating glass cloth in strip form.

Guess I should go to home depot and look to see if that yellow stuff is really fiberglass. It looks like plastic.

http://www.grip-rite.com/us/en/products ... joint-tape

Er, No, actually it was the heavier 8” wide cloth formed into a tape , from the Boat shop... not expensive ,thick, very strong ... I use the drywall fiberglass for my RC Foamie models , we also have a Kevlar and carbon fiber weaves too ... but that gets expensive ... and difficult to apply , glue and sand /finish ... as you know ... We’ve got lots of the exotic stuff in the shop, just the common stuff we keep running out of ...

Our West type (laminating) Fberglass tape was left over from the first TD which was plywood and all seams got EPOXIED ( West) and the glass tape ... Plenty left over in the roll for the Foamie #1 ... Looking back we should have fiberglassed the whole roof , the sides were just fine as plywood ...

gizmotron wrote:Fiberglass fabric strips are water resistant too. I should get a sample and test it first. That silicone is just a spray on treatment. It still allows the glue to flow into the nooks and crannies of the fabric, where it creates a strata layer formed by dimensional imperfections. It's the dry glue in the weave that does the sticking. Same is true of the fiberglass.

Yes but the fibrglass mesh has larger holes right? It is the dry glue in there that does the sticking but it needs to get in and it helps a lot if it bonds to it as well. Water soaks right into cotton canvass, it doesnt for waterproof or resistant canvass. Glue is like thick water...
Basically nothing sticks to silicon. If its sprayed on the canvass for waterproofing it has filled the weave enough to keep water and therefore glue from soaking into it right?
Anyway, better try some before you buy a whole bunch.

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All those composite aircraft have foam cores and glass skins. They all have stringers that have helped prevent delamination. My wind surfboards have stringers and are made of foam & glass. They take a huge beating in 45 mile per hour winds. Wanted to believe that PMF was strong enough for a Standy that sticks up three feet above my tow car and is nothing but 80 lbs of 25 psi foam. Add to that that I would put 100 lbs of solar panels on the roof.

So, I'm going to put stringers in the walls and roof, shave out 1/8" depressions at every stringer on both sides and epoxy & glass the 4" wide depressions. That will put a coat of fiberglass and epoxy in the depression, bonding the stringers to the surface of the foam. Later a surface coat of fiberglass and epoxy skin bonds the combo wood & glass I beams together with the 2" thick composite method. This is the only way to build bomb proof. It's not that the foam can be pulled apart and delaminate because the bond is broken at the foam's surface. It's that the fiberglass skin must fail first, and that is unlikely. This is what works for composite aircraft. This will work for the takeoff speed of a medium sized Cessna. That's around 60 MPH not considering headwinds. There is no way that I can trust TB2 to TB2 composite construction. I would love it if that was good enough.

It's quite fumey but the E6000 glue for jewelry and such bonds anything to foam and is strong. Can get it in contractor tubes on Amazon and stays very flexible and will stretch an inch before starting to fall. Laminate anything inside and out with it and it would be a massively strong and waterproof barrier. Completely spread across entire surface and a hard enough overlay would give strength to carry anything on the roof. Used it in many different ways and surfaces and have yet to find anything it won't glue.

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