Ok, Legos. Just like assembling Lego blocks, or arts and craft class, gluing a project together right?
How hard can it be? It can't possibly take very long.
There was a van gathering in two weeks and meeting a friend in Vegas in three, should be no problem to make those rendezvous. Right? Like it's 13, 4*8 sheets glued together and then covered in glue and canvas, then painted with a couple coats of water based paint.
Easy peasy.
Not so fast Mr Naive. Didn't make either appointment with a completed box that I felt was capable of making a 6 hour road trip.
Oh, you want to know about the build?
Back to the nitty gritty details.
Foam, the building block, had 18 sheets, a few extra just in case. You know, the 10% safety margin cushion.
So before I bought this foam, had to inspect and determine suitability and strength. I was sold on polyiso, not so much on Polystyrene. But the price was attractive and the seller claimed he himself had built one that I could see. Off I set to check it out. Well it was a sorry, neglected slide in camper, flaking in the sun, cracked body filler peeling off of the seams. But it was solid enough and the massive four inch thickness was reassuring. This must be the stuff Foamstream was built with. Could be done and should be adequate. However, didn't recall Foamstream ever making it out of the yard. And I would be building on a van frame, another level of challenge. What could go wrong?
So off I went to get bucket loads of paint, rolls and rolls off cloth, tubes and tubes plus jugs and jugs of glue. I was ready to start on assembling a box with 400ft2 of surface area. Kind of on the big side for a tnttt build.
Get a move on, got two weeks to cut, glue together, lay more glue on the sides, wrap with cloth and then slap on coats of paint. I was working on borrowed time on borrowed property. I hustled but the short winter days and chilly mornings limited my time.
And I built it all singlehanded.
Luckily, I am massively strong and capable to manhandle 20lb sheets of styrofoam.
So here was the plan from many nights of pondering, researching, and on the fly assessment since I switched to Polystyrene at the last minute. The walls and roof would be 3.5 sheets long. As with any build, the corners and seams are weak points. Like drywall, they will need to be set, bonded and filled, seams which are prime to cracking and coming apart from any stresses or loads. And that's for a stationary house. I was adding much more flex and movement with a vehicle going 75 mph down the highway. Who again said that this could be done so that I could blame them in the case of catastrophy? George, right. I had his number just in case.
Better overengineer just in case so as not to leave an avalanche of Polystyrene in my wake going down the highway. But at least I know it wouldn't hurt anyone. Tiny beads of Polystyrene, sounds like a song.
Ok how to reinforce the seams for added strength. The roof and edges were my main concern as that will be holding the box together, bear the brunt of the flex and movement, be subject to the most stresses goin down the road, over bumpy rock strewn dirt roads, through the occasional ditch and gouged road.
The roof joint was going to get the flex from the chassis and sidewall flex and it was going to be levered, enhancing the flex and movement. Here's the solution that I developed. God, I hope it would be enough.
I would countersink 1*4 boards flush into every side interior seam for extra strength, ridgity and increased bonding area for the joint. Doubling the bonding area in essence.
The corners as well would get extra wood for strength and extra bonding surface. Would notch out the sidewall roof joint for it to sit properly, tight and once again give increased bonding area for extra strength at that weak point.
For a long time I thought about wood vs metal framing. Wanted to go metal to eliminate the rotting wood issue. But the increased cost, increased assembly time, bonding issues negated the benefits. I had 4" of barrier to any wood which would be used only in the interior and it was cost favorable, flexed, bonded well, was ready to work with and readily available. It wasn't impressive like metal, but durable for the application and good enough for interior use. But the challenge was then, how thick and what sizes to use? The whole purpose was to build light yet had to be strong enough. I decided against a traditional ply and frame build for weight reasons. How to make a strong and light frame to increase the strength of the foam sheet for this application? And with only hand tools?
Don't know but here's what I did.
Some use a router to make a channel to glue in their wood board. Didn't have or want a router. Messy and long routing out channel. George uses the hot wire method on polyiso. Too long and slow a process, I had deadlines. Would it work on Polystyrene? I determined from trials that I could quickly cut my sheets with a circular saw in a maelstrom of Polystyrene beads. Static cling anyone? And that I could channel out the edges of two adjoining sheets, insert a 1*4 board to stiffen the joint, give increased bonding area and increase the load bearing capacity. Sounds good but will it work?
Chose 1*4 as not to costly, give two inch overlap on each sheet, double the glue bonding area and reinforce the seams, seemed about the right width. Of course wider would be better, possibly six inch wide 3/4" plywood or wider? Time will tell. Ideally I wanted to go every 24" but I could cut a channel out of the edges easily. A channel down the middle would require a router and I decided against that. Figured that if I needed to, could surface mount if required later in the build.
Then for the corners, could add a 2*2 to screw the insert boards together at that joint. Glue and screwed, shouldn't come apart, right? Right?
Where's an engineering neighbor when you need one? I was in cowboy country with horse ranches, I was on my own. The only assistance that I got was from a neighbor encouraging me to finish quickly lest be reported to the local authorities for my activities. He gave me a one week deadline, great inspiration. Nice guy huh?
Ok, assembly plan decided upon. I would overcome obstacles as I reached them, there was no blueprint or design that I could copy. A simple basic box was the plan. It should be basic, easy to build with basic hand tools and quickly assembled. The details I developed as I went along, God help me.
Now the walls were going to be 6'6"*12' panels. The roof 7'*12', rather large. Reinforced with 1*4 at every seam and joint. The seller told me that a sheet weighed 20 lbs, so about 100lbs per panel. Not too heavy but cumbersome. So I could assemble a 4' side wall, roof panel and side wall, and mount on the van, then continue to add another section. Assemble the box and then PMF the entire exterior which is what George does. But my sides and height would be 7 feet and that is longer than me armspan. That's a problem. I could assemble one section, PMF the 4' wide section, assemble another section, PMF that and keep going but was concerned about overlap, the finish smoothness and strength by doing PMF in sections over a couple days.
What I decided upon was to assemble each wall with 3.5 panels, using the flat bed of the van as my working table, assembling and gluing on the large flat horizontal surface. Build one wall, then the other, then the roof, PMF each separately while flat on the horizontal would be easiest, assemble the three walls, finish the joints from PMF overlap. Sounded good to me. Remember, developing the method on the fly, in the moment.
It worked out actually rather well. Couldn't see applying PMF on a vertical wall alone, that was 12' long and 10' up in the air the way George does it on his teardrops. Just too large and I'm not a big guy so limited reach. Place a sheet on the bed, notch out the channel, do the same with a second, add glue and board, repeat for the next sheet. Compress with straps to the front of the bed and allow to set overnight. Repeat with other wall and for roof.
Voila, three panels complete.
Make it so.