TERRA6, Van cab and chassis 7*14, 4" Polystyrene

[GPW]

[Projector]

Things learned, costs and various aspect considerations unique to this 7x14 build.

4x8 teardrop is efficient and ideal construction for 2x4x8 sheet sized foam. Going bigger requires more reinforcement, complexity and 2-4x more time, material and thus cost due to size, spans involved. Who knew? Now you do! Lol

Glue 4x8 panel assembly
In my case, 4 inch foam required 2x more bonding glue than 2 inch foam. And another 2x glue due to extra joint reinforcement for larger size. Countersunk boards at every wall joint and corners to increase wall and corner strength. Adding extra reinforcement ribs and spars reqd another 2x glue so approx 4-6x more bonding glue required overall.
Basically, used a 30oz tube of PL3x for every 7 ft joint. Calculated roughly 40 glue joints @$8 = $320. Couldn't believe initially how fast that i went through glue but with afterthought makes sense. Ignorance is bliss and i was naive.

. Fwiw from this and previous experience, not impressed with liquid nails exterior and would only use for something that i might have to disassemble. PL3 however, i would recommend for anything permanent.
Fabric
Thicker Fabric, more glue n paint required. I used hf drop cloth, don't know weight or how it compares to typical duck cloth ordered by others, but it's heavy. Using TB3 required less dilution (20% used) thus more needed. Wanted the improved water proof over TB2 and found out afterward that TB3 was much more viscous and seemed much too thin when reduced to 50%. Not certain at this stage that it is really necessary or better. Have no real test to confirm this other than a basic done initially which wasn't impressive in any regard, both dilute and full strength.

The fabric to foam bonding and exterior skin puncture resistance are 2 areas that are marginal imho, from my unique experience and build method. IIRC, used about 10 gals of TB3 for approx 400ft2 or $250. I only glued the inner bonding side since i had so much cheap paint for the fabric exterior.

Fabric to foam bonding
Found this marginal at best. Even full strength. Steps that I took to improve as much as possible included using full strength TB3 around the perimeter of each wall approx 8-12 inches figuring that the edge adhesion was the most important and would prevent lifting that would start from the edges. Also wrapped and stapled the fabric strategically where i could to the front wall at the sides and to the bottom of the walls at the floor. Had no confidence in the ability of the TB glue in itself for this critical aspect without mechanical attachment.

With the much larger surface area size involved, the forces and stresses on the skin are much greater for a bigger unit. Bigger sail basically giving greater lift from air flow. Ideal for an airplane or sailboat, not the canvas on a PMF foamie. Now if i could figure out how to reduce drag and get aerodynamic lift, without resistance, from PMF to increase mpg....

Puncture resistance is minimal compared to a hard side. Fine for my application as it's mostly wide open travel. Not ideal where lots of branches, rocks or other impact potential areas.
At this stage, question the PMF method time/cost/value over just laying a coat of paint/roof silicone directly over foam. Possibly just reinforcing seams with glued/stapled fiberglass joint tape, IF at all necessary? Especially for a 4x8 teardrop. Or just notching/ dovetailing joints? Interesting debate topic?

My personal assessment of the sock strength theory is that it's marginal in my application. Can't speak for others of course. Imho, frame and joint bonding account for most if not all of the strength. I really don't see from my tests and construction by lifting fabric off foam that the sock theory accounts for much of the retention strength of the entire structure. It may impart some retention keeping the roof/ wall seams from splitting apart but can't see this as more than minor imho. Purely conjecture on my part. Test with a covered and uncovered box would be one way to quantitatively assess this.

I would think that reinforcing the corner with right angle roof/drywall channel glued in place could be sufficient and, where else needed, could give same strength without pmf time and trouble. Worth a try to find out. If insufficient, than pmf as normal.

I built some wheel arches with 3/8 plywood that I then entirely covered using multiple coats TB2 full strength on all sides and left over cloth. The ridgity didn't appear much improved imho as it still greatly flexed. The glued skin has to add some strength but not what i would call ridgid strong. Imho. Once again, without test data specifics, vague generalities and just my impression.

Framing
This was the biggest stress of the build. Would my design have sufficient strength reinforcement to maintain structural ridgity for the application? . 1x4 glued to each vertical wall joint 4 ft spaced. 1x4-1x2 t-truss spans for the roof. Extra horizontal reinforcement across the back wall. All based upon 1.5 inch plywood floor over 4x4 cross ribs on chassis frame and 3/4 plywood front wall. I had figured that I would start with this level of framing and could always add more later if needed.

Sounds good in theory but best to start off strong cause if you have a problem later, it will be at the worst moment, could be dangerous and probably not so easily repaired realistically.
Another stress was mounting the heavy solar panels to a foam roof. My 1x5 inset cedar boards were heavily glued but no guarantee wouldn't delaminate at the foam if the stresses exceed with force- impact and or air lift at speed. So far so good.

I call my rig an oversized backpack beer cooler.
Happy that i built it and satisfied with the results. It has performed well enough for its intended task so far maintaining comfortable inner temperatures as much as possible (10-30 degree improvement) and stayed dry. It has been subjected to wind, rain and hail with no issues so far. But of course it's resistance is much less than a hard side would give. It's between a tent and a hard sided trailer. I monitor weather and wind as this is it's major weakness.
While strong enough for the majority of the weather that I am located in, would not build this if I lived in tornado alley, hail or snow central. That would require a stronger frame and a more rigid or resistant cover skin imho. It is still possible, should i decide, to add a stronger exterior skin which is why i went PMF. And possibly could have taken the approx $4-500 overall cost of PMF and applied that to another covering could be debated.

That is something for everyone to consider for their own build, preference and situation. This has suited my situation and budget. Built with the EG&G method - Economically Get er done, Good enough. Cost to build is in the $1500-2000 which isn't as cheap as i had hoped but that was unrealistic. Hard to budget accurately when you have no clue. Lol.

This post was intended to share and help others learn from my experience. Good luck to you all.

[ghcoe]

Thanks for the update. Glad it is still going strong.

There are a lot of things here to mull over for sure. I think that your build is probably the biggest that we know of at this moment so it is good to get feedback from your experiences. Which is more than most for sure. George.

[JazzVinyl]

Just a little pizzazz plus matching wheeled luggage.

I love your "foamie motor home"!

Thank you for being so kind as to share your build experience as well.
What an attractive and unique build!

[Projector]

Thx JazzVinyl for the compliments.
Like the way your foamie turned out as well.
Disco lights to go with the jazz vinyl?

[JazzVinyl]

[quote="Projector"]Thx JazzVinyl for the compliments.
Like the way your foamie turned out as well.
Disco lights to go with the jazz vinyl?[/quote]

Let's call it "mood lighting" instead of Disco :-)

I do love my Jazz on Vinyl :-)

[Terra6]

Due to technical difficulties, have renamed myself from Projector to Terra6.
My old phone just cracked up and died from an overdose of punch lines.
New phone and New identity.

[Terra6]

Thx JazzVinyl for the compliments.
Like the way your foamie turned out as well.
Disco lights to go with the jazz vinyl?

Let's call it "mood lighting" instead of Disco :-)

I do love my Jazz on Vinyl :-)

I'm a former disco dude and it's outdated and not necessarily positive anymore but i still luv it.
Mood lighting does sound better.

[Terra6]

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Ongoing projects with PMF.
So in the spirit of get er done good enough with the initial build, my drop down bed was 2 leftover sheets of 4x8 3/8 ply glued and screwed together with 3 -1x4 pine board on edge and center to reinforce. Regular coil mattress on top.
Added a steel brace on the hanging front edge for...
Any acrobatic gymnastics that might spontaneously occur.

While it has worked out supportively fine for sleeping and Olympic events, it is rather heavy to lift. So looking at ways to reduce weight and improve folding up.

Thought why not make a wood cot frame with leftover fabric over 2x2 and then pmf the canvas for extra strength and rigidity. You know, the pmf is strong often recited here.
Another perfect application?

Well my experience wasn't overly successful as well as planned.
30x76 btw.

See pics for final unit. Looked good, came out well enough but...

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Staple fabric to the frame. Hmmm, too much stretch and needs to be tighter. Remove staples, stretch tauter, restaple. Better, about an inch of stretch in the middle. Now time for the wet and shrink trick to make it tight as a drum.

Er, no.
I didn't have much if any shrink when i did the pmf overlay on my Styrofoam. Just Thought because i was a newbie and didn't know what i was doing.
Yes, that can still be argued.
In my humble defense, 18 months and counting and still on the road with it's most recent test being 40+ mph Christobol winds and gusts.
Still in 1 piece, warm and dry.
But i digress.

The harbor freight dropcloth canvas has not shrunk at all in both of my applications. My bed frame still had as much slack and stretch after wetting. Ok, maybe it will tighten up with my addition of TBII. One coat undiluted around the frame, 2 coats 50 50 both sides all over. Rigid canvas good.
No shrinkage, same as before.

Install and test, not great. My 175 lbs stretched the fabric to about 3-4 inches of sag in the middle. Acceptable but definitely didn't shrink drum tight with water and glue.

Then i tried placing some left over ply on the canvas which reduced the sag in half. But then what was the point of the pmf canvas?
Next i had bought a memory foam topper that was solid 2", no egg crate. Tried 1, 2 and 3 layers. 1 wasn't enough and could feel the ply underneath. Hard
The 2" memory foam will compress to less than 1/2 inch, not giving much comfort. plus I'm a side sleeper mostly so narrow specific pressure points.
3 layers was too much and felt like being entombed like a mummy in the foam. Memory foam compresses too much to basically nothing and not being resistant enough alone on wood. I had bought a quality foam topper brand btw, Lucid.
2 layers is not bad but not ideal. Certainly not like sleeping on a cloud.

So i am at the stage of plan b, thinking of just going over with ply, bypassing the pmf cloth totally.
Considering other minimum cost efficient options like webbing, or???
open to suggestions???

[JazzVinyl]

I'm a former disco dude and it's outdated and not necessarily positive anymore but i still luv it.
Mood lighting does sound better.

Ha :-)
I am of the generation prior to the rise of disco. The LED strip light was never intended to mimic the "disco" music genre,

In actual use, there is a "night light" mode that is almost always used. It is a soft and constant orange glow that turns itself off after 30 mins.

Cheers!!

[JazzVinyl]

Ongoing projects with PMF.
So in the spirit of get er done good enough with the initial build, my drop down bed was 2 sheets of 3/8 ply glued and screwed together with 3 -1x4 pine board on edge and center to reinforce. Regular coil mattress on top.
Added a steel brace on the hanging front edge for...
Any acrobatic gymnastics that might spontaneously occur. 8)

While it has worked out supportively fine for sleeping and Olympic events, it is rather heavy to lift. So looking at ways to reduce weight and improve folding up.
Thought why not make a wood framed cot frame with leftover fabric over 2x2 and then pmf the canvas for extra strength and rigidity. Yeah know, the pmf is strong often recited here. Another perfect application?

Well mutt experience wasn't overly successful as well as planned.

Looking good :-)

[John61CT]

I'd like to see for lightest strong bed platform

8020 type but rectangular profile aluminum tubing

laid out precisely supporting the poly mesh shelving used for commercial greenhouse shelving, iirc 18" centers

those filled with medium density expanding PU foam for insulation

PMF'd for added tensile strength and a smooth surface.

The real challenge, make it quick and easy to break down to store out of the way in minimum space.

[Terra6]

Aluminum could be ideal, except for the cost.
And how to bind or weld with either crazy glue, duct tape or zip ties.

Actually got excited when i picked up an aluminum, military style cot from recycle that i had hoped to transform for my application. Unfortunately it had many reinforcements due to the nature of folding setup that made it surprisingly heavy, with short tube lengths and cumbersome. Even folded up it was surprisingly bulky and wouldn't work in my application.
I needed solid, single piece platform to store flat along a wall, and it wasn't. Cut out 4 longest pieces (>3')for future use. Using 2 pieces as legs for center bed supports now.

Some of the options considered
- rope support under cloth. Comfort from rope pressure?
- cloth spray foam cloth sandwich using existing 2x2 frame. Effective?
- paneling spray foam paneling sandwich existing frame. Cost benefit?
- 3/8 ply over existing frame, which i have. Likely quick n easy
- 1x4 slats on top. Gaps n mattress foam?
- find and convert an existing lightweight bed frame. Locate?
- lighten existing 3/4 ply base with holes and replace mattress. Doable. How much lighter? Remove how much yet retain strength for gymnastics?
- learn to sleep in a hammock. Probably not too suitable for spontaneous moments.
- develop tantric levitation and meditation repose methods bypassing the whole bed issue.

[Terra6]

Some May wonder at the purpose of my matching trailer.
It's for my RC toys.
See pics for forum entertainment value.

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The roof makes a perfect helipad as you can see.

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Converting a boat trailer and still retaining it's low floor makes it easy to launch my tanker.

[Terra6]

Another great point for PMF is that it is a blank canvas, primed and ready for any design or decor. Mine has been enticing me constantly to get more creative with it. Awakened my inner Bob Ross? Having no previous freehand painting experience beyond childhood watercolors, decided to give it a shot, as what's the worst that can happen? Can always do the cover-up trick with white paint.

In my spare, sub conscious time, think about developing a design concept for Terra6. Maybe now is the time to start?

Started with a little sunshine, which always brings rays of happiness with it.

Actually quite pleased with how it turned out.
Encouraged to continue, bought various colors of art paint.

Ideally, the sun will create some warmth and happiness when viewed. The purpose of art, visually stimulate our emotions.
A sneak peak of what's to come...

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