Building our box out of wood?

MTVR

Well-known member
I know that most people are trying to build something light enough to work with their particular vehicle, but our MTVR has a 30,000-pound payload capacity, so there may be solutions that wouldn't work for other people, but would work just fine for us. Our MTVR's flatbed is rigid, and it's mounted to the frame with springs to make it torsion-free, so I'm not concerned about damaging the box from twisting off road.

We've explored the downsides to using an ISO container, and we've looked into using a dry van box as a basis...but what about building it out of wood, framed like a house, with plywood on the inside and outside, and everything glued and screwed. Flat-roofed.

This would give us total control over the dimensions that we're looking for, without having to modify something that was designed for another purpose.

This would give us something that is structurally strong enough to mount our 600-pound gun safe to, and strong enough to tie down a 400-pound motorcycle to. I have no idea how we would attempt that with FRP/foam SIPs.

This would make it easier/simpler to adapt certain design elements to, like our desire for a "drawbridge" type rear door/platform/ramp and rigid fold-down awnings to protect the windows against tree branches off road.

We would be able to build it ourselves, without any special tools or skills.

The materials could all be purchased locally from Home Depot at an advantageous pricing point, without having to pay to ship a giant stack of SIPs to us.

We wouldn't have to deal with thermal bridging of an aluminum or steel frame. Wood studs are still thermal bridges, but not nearly as bad as a metal frame. We could do the studs on 24" centers (instead of the standard 16" spacing) to reduce thermal bridging by a third.

We could make the walls, floor, and ceiling thicker, to allow for more insulation- we could do 5.5" of polyiso in the ceiling, and 3.5" in the walls and floor.

We could use off-the shelf insulated residential windows.

My biggest concern, would be how to keep water from getting into it. On the inside, we could use a vapor barrier, seal the seams, and seal the interior paneling itself with paint or epoxy or something. On the outside, I guess we could do the same thing.

What do you guys think?
 
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MTVR

Well-known member
Why only 2" of foam? If we use 2x4 studs, the cavities would be 3.5" deep.

And would I need to actually fiberglass the entire exterior with fiberglass cloth, or just use the epoxy resin to waterproof the exterior of the wood itself?
 

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1000arms

Well-known member
I know that most people are trying to build something light enough to work with their particular vehicle, but our MTVR has a 30,000-pound payload capacity, so there may be solutions that wouldn't work for other people, but would work just fine for us. Our MTVR's flatbed is rigid, and it's mounted to the frame with springs to make it torsion-free, so I'm not concerned about damaging the box from twisting off road.

We've explored the downsides to using an ISO container, and we've looked into using a dry van box as a basis...but what about building it out of wood, framed like a house, with plywood on the inside and outside, and everything glued and screwed. Flat-roofed.

This would give us total control over the dimensions that we're looking for, without having to modify something that was designed for another purpose.

This would give us something that is structurally strong enough to mount our 600-pound gun safe to, and strong enough to tie down a 400-pound motorcycle to. I have no idea how we would attempt that with FRP/foam SIPs.

This would make it easier/simpler to adapt certain design elements to, like our desire for a "drawbridge" type rear door/platform/ramp and rigid fold-down awnings to protect the windows against tree branches off road.

We would be able to build it ourselves, without any special tools or skills.

The materials could all be purchased locally from Home Depot at an advantageous pricing point, without having to pay to ship a giant stack of SIPs to us.

We wouldn't have to deal with thermal bridging of an aluminum or steel frame. Wood studs are still thermal bridges, but not nearly as bad as a metal frame. We could do the studs on 24" centers (instead of the standard 16" spacing) to reduce thermal bridging by a third.

We could make the walls, floor, and ceiling thicker, to allow for more insulation- we could do 5.5" of polyiso in the ceiling, and 3.5" in the walls and floor.

We could use off-the shelf insulated residential windows.

My biggest concern, would be how to keep water from getting into it. On the inside, we could use a vapor barrier, seal the seams, and seal the interior paneling itself with paint or epoxy or something. On the outside, I guess we could do the same thing.

What do you guys think?
Most rigs don't like 4x4 wood frame construction, insulated, and skinned inside and out with 3/4" plywood, but I don't think that would be an issue for your rig. :) Fiberglass, or poor person's fiberglass, on the outside ... (Is that an echo I hear? :cool: )

Glue and screw. Rigid closed-cell for insulation, 2" +1.5" bonded together, and the plywood sheathing bonded to the foam and frame, inside and out. Cabinet grade plywood on the inside.

Look at glue and screw boat building for some ideas too.
 

The Artisan

Adventurer
Why only 2" of foam? If we use 2x4 studs, the cavities would be 3.5" deep.

And would I need to actually fiberglass the entire exterior with fiberglass cloth, or just use the epoxy resin to waterproof the exterior of the wood itself?
No need for 2x4 studs. Use a 2x2 screw it to it to your sip floor make a grove in your
Sip bottom, drop it over your 2x2 support and screw.
Epoxy resin would work thick coats. The frp comosite panels I make are for light weight applications at 1lb per sq a little more coated in 1mm of polyurea rubber coating.
You can build how you want up to you since weight is of no concern
Kevin
 

Joe917

Explorer
What is the budget? This type of wood frame build is usually an attempt at a high end expo truck for peanuts. You will end up with a pile of firewood on the back of your truck. There are many composite panel suppliers that can help you with design and structural connections for your gunsafe and anything else you can think of. You are going to have to invest a lot of time in a truck build, don't devalue your time with unsuitable materials.
Weight is always a concern no matter how big the base vehicle.
 

The Artisan

Adventurer
What is the budget? This type of wood frame build is usually an attempt at a high end expo truck for peanuts. You will end up with a pile of firewood on the back of your truck. There are many composite panel suppliers that can help you with design and structural connections for your gunsafe and anything else you can think of. You are going to have to invest a lot of time in a truck build, don't devalue your time with unsuitable materials.
Weight is always a concern no matter how big the base vehicle.
I was guessing he was on a budget so I did not even mention other options
Kevin
 

MTVR

Well-known member
Most rigs don't like 4x4 wood frame construction, insulated, and skinned inside and out with 3/4" plywood, but I don't think that would be an issue for your rig. :) Fiberglass, or poor person's fiberglass, on the outside ... (Is that an echo I hear? :cool: )

Glue and screw. Rigid closed-cell for insulation, 2" +1.5" bonded together, and the plywood sheathing bonded to the foam and frame, inside and out. Cabinet grade plywood on the inside.

Look at glue and screw boat building for some ideas too.
We are looking at 4x6 outer rails in the floor to anchor our box to the truck bed, and a 4x4 built into the ceiling/roof to anchor a pair of small ATV winches to power our brawbridge back door to, but other than that, I would be inclined to just use 2x4s, with the studs on 24" centers.

And 3/4" plywood might be overkill, even for something like this...
 

s.e.charles

Well-known member
i'll bite: how much experience do you have building things?

do you have a thorough understanding of the properties in materials you're considering?

do you know the difference in lumber grades? or plywood? or adhesives? hardware?

there's two ways you build could turn out:

#1. fantastic

#b. woefully failed

initially, if you think home depot will supply adequate materials in toto, you're kind boned from the git-go.

YOU have the power to make those decisions, but each will carry consequences.
 

Rando

Explorer
To second what Joe asked, what is the budget and long term goal here?

If the idea is to make a 'tiny house on wheels' for somewhat local exploration, and it is really about the project, then 2x4 house like construction seems like a good option. Cheap, easy and fun to customize and get creative with. On the other hand if the plan is to have a long term or long distance exploration vehicle (think Earthroamer, GXV etc) that you would like to recoup some investment from, then wood framing is probably not the right option - both from a practical longevity reasons and from a re-sale expectation reasons.
 

MTVR

Well-known member
Our goal is exploring the continental U.S. for about the next five years, full time.

And resale value is not a major part of our decision-making criteria- we're building it for us to use, not for the next owners. No matter what they're built out of, you're going to lose money on these types of things on resale, and the more specialized they are, the more difficult they're going to be to sell. Ours is going to be pretty specialized.

As an example, if we spent $25K and wrote the whole thing off in five years, that's the same loss as spending $100K and selling it for $75K in five years...
 
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MTVR

Well-known member
Can someone recommend some vendors for composite alternatives?

Maybe I'll reach out and see what they can do for us...
 

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Rando

Explorer
That is a good point, but you will probably enjoy living out of a $100K house for the next 5 years than a $25K house. I imagine a wood framed system would take a lot more upkeep than composite construction, but maybe that is part of the fun and not a concern.
 

MTVR

Well-known member
This type of wood frame build is usually an attempt at a high end expo truck for peanuts. You will end up with a pile of firewood on the back of your truck.
We're not talking about nailing together a shed to put on the back of our truck.

We're not attempting something "high end", and we're not attempting to do it for peanuts...
 
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