Hybrid Foamie Standie Toyhauler Build

[MatTech]

I've been lurking in the shadows for quite some time, gathering info and putting it to use. I guess it's time I started sharing.

For a long time I've wanted a mobile moose hunting camp so that my brothers and I can get together once a year for a couple weeks. Last year was my first time actually moose hunting and I bought a "small" 18' Sunlite Koala TT which had been modified and "maintained" with excessive caulking. I bought the trailer knowing full well that I would strip it to the frame and rebuild it.

The koala was a hybrid pop out with the front and back teenage removed and the hatches sealed shut so the only bed was the dinette. There was water damage in the walls but all the equipment was immaculate. I temporarily outfitted it with 300 watts of solar and 2 GC2 batteries as well as 2 30lb propane tanks. After two weeks of hunting and 140km of pothole filled logging roads I knew exactly what needed to be done.

To date I have stripped the trailer to the frame, doubled the crossmembers, added steel fenders to the tandem torsion axles, changed the front jack, painted the frame, rewired with new LED lights and sheeted the floor with 3/4" pressure treated plywood. I have just started building the hybrid foam walls.

The inside dimensions of the livable space will be 5'6" by 13'9" (the exact dimensions of the plywood floor) I will be mounting the walls outside the frame onto an angle iron ledge flush with the bottom of the plywood floor to prevent any chance of water seepage. Walls will be 2" foamular C300 XPS with the framing routed into the foam on the inside to keep the outside mostly solid foam. Studs are 1" x 1 1/2" ripped from 2x6s so even where the studs are there is no thermal bridge, just half insulation. The stud frame is constructed with dowels, glue and screws for durability and it is being bonded to the foam with gorilla glue and screws with plastic washers.

I plan on covering it with PMF on the outside and am currently in the process of testing alternative adhesives to TB2. So far Durapro foamboard adhesive is looking extremely promising, it's a latex adhesive and after 24hrs separating the canvas either ripped out the foam or pulled fibers from the canvas.

I know this was a long winded post but I have a lot to catch you guys up on. Before I post photos I wanted to be sure that tapatalk automatically resizes them for the forum, is that the case?

Looking forward to getting any feedback on my plans. More to follow.

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[FM82]

Sounds like an interesting build! I'll be following. As far as the pictures, they aren't automatically resized. There's a thread that goes over the sizing, but I'm thinking 600x800 is the requested size for thread posts.

Edit:
Here's the link that will get to the photo info.
https://r.tapatalk.com/shareLink?url=ht ... are_type=t

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[MatTech]

Thanks for the info on the photos. I read the thread on how to post photos but thought maybe tapatalk resizes them automatically. I'll pretty much always be using my phone on the forum so I'll see if I can create a folder of resized pics.

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[FM82]

Tapatalk will resize them a bit. I didn't realize until recently, but they are still pretty large though. I ended up resizing mine before uploading through Tapatalk.

I did the same with mine. Just created "Forum Photos" folder so I could keep them separate.

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[MatTech]

I've started a personal album with resized photos of my progress so far. Pictures have description of what was done. I've added the most recent pic of the first wall here as a teaser

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[MatTech]

The basic idea of the build is that the platform seen in the pictures will be the floor space. The walls will mount directly to the frame outside the floor (inside the fenders). Walls will be 6' 6" tall and the roof will have a peak 6" higher for drainage. The rear 9' of the trailer will be open space to haul my 1973 Terra Jet and will have fold down couches/bed. Rear door will either be a ramp or open upwards and I will stow my aluminum ramps under the deck. In the front will be the wet bath, sink, stove, fridge and stationary cabinets. Batteries and propane will be on the a frame up front and eventually I will build walls around them turning the trailer into somewhat of a v nose cargo trailer. I will insulate the floor from underneath and all tanks will be located inside the heated space for cold weather operation. Everything from the donor trailer is being reused except the body.

This plan has gone through many changes, originally I wanted a slide on camper body that telescoped down like a hilo but in the end the axles have brought me to my current plan. They are dexter torflex axles rated for 2200# each so 4400# is my max weight with the 1000# Terra Jet and supplies on board. I had to cut all the extra weight involved with a second floor structure and telescoping mechanicals.

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[MatTech]

More progress today. The left side wall is almost all foamed

Starting to get a rhythm with the router. I'll definately need more GG before I'm done this build. Even with the 36 ounce bottle it goes fast with all the surface area of the routed in studs.

Should be solid as a rock when it's all done.

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[FM82]

Looking good! Nice touch with notching the foam. Man, I can only imagine the mess that made haha.
Kind of makes me wish I had planned my dimensions around insulating the same way.

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[MatTech]

With the shop vac hooked up to the router it only makes a little mess. The flip side is that its cumbersome to maneuver the router with both a cord and hose attached.

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[FM82]

With the shop vac hooked up to the router it only makes a little mess. The flip side is that its cumbersome to maneuver the router with both a cord and hose attached.

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Dang. That spoils some of the fun. Aside from having to clean it all up of course. Seriously though, not a bad idea. I'd definitely be the one to dive in and not have a vac system connected.

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[Mr. Lahey]

You have me curious. Just wondering why you notched the foam?

Since you have a full wood frame couldn't you have cut thinner foam to required sizes. Fit them in the framing opening spaces.
Then sheath the whole wall in full sheets of thinner foam?

In any case your work looks great. I look forward to watching your progress.

[MatTech]

My thought process on grooving the foam was two part. For one buying two sheets of 1" foam was more expensive than buying 1 sheet of 2" and the glue required to laminate the exterior foam would have added even more cost. The other thought was that by grooving foam with straight grooves it would pull the frame into square automatically and add even more strength since my 1" X 1 1/2" studs were quite twisty and some were bowed.

I only have 2 1/4 inches from the outside of the frame to the inside of the fenders and cutting in on floor space wasn't an option. All things considered grooving out the foam seemed to be the most economical and structurally sound, time to install not being accounted for.

Also I really wanted to try it so there's that.

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[MatTech]

Made some more progress today. The left wall is completely foamed and I finished the framing of the right side wall. The framing went a lot quicker on the second wall since I've found my rhythm.

I will foam the second wall then I will set myself up to work on the walls flat on sawhorses and start filling the screw holes with durapro. I gave polyurethane canned foam a try as both an adhesive and for filling the screw holes but It was no fun at all. I'll stick to the gorilla glue from now on for gluing the foam in place as it is way less messy and doesn't expand as much. As for filling the screw holes, the canned foam doesn't adhere enough to the plastic washers. The only thing I will use it for now is filling foam to foam gaps.

Made a few little mistakes, mostly second guessing myself and turning out to have been right the first time lol. In case anyone is wondering why none of the windows and door have headers, this is because I will install a full length header at the very top on the inside to distribute load evenly. It will be inside the full length cabinets anyway so no sweat there.

I really should take more breaks and take photos of the process but when I get going I completely forget.

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[stcyrwm]

Thanks for sharing all of this! I have been looking around for a larger foamie that is more in line with the size I would like to build.

What was your reasoning for the width that you went with? I am thinking of going with something similar construction but wider and just wondered if there were issues with going wider eg 7 or 8 feet?

Regardless of that, congrats on your progress, it looks awesome! I can't wait to see it come along.

Thanks, Bill

[MatTech]

One of my earlier plans was to build the trailer out to 7'6" wide to match the outside of the wheels just like the original trailer. The added weight of welding on a frame structure to the sides of my 5"6" wide trailer frame as well as the loss of rigidity not bolting directly to the side of the frame was what made me decide to go smaller.

Since this will mainly be my hunting rig it needs to be able to survive terrible roads and tight off road trails. Being able to see both axles on both sides of the trailer in my mirrors will be very advantageous navigating the off road parts. Fully loaded for two weeks off grid this thing needs to weigh in at under 3400 lbs in order to have capacity leftover for my 1000 lb. Terra Jet.

I only need this to be big enough to get the job done. When I was still in the planning stage I made a scale plan of the trailer in its flatbed form and also made scale cutouts off all the equipment (shower, stove, sink etc) and slid them around on the frame model until I found a combination that fit. Once I came up with a floorplan that fit everything I needed and left room to fit the terra jet inside, I made the decision to go narrower.

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