Teardrops n Tiny Travel Trailers

Hello, new V Nose here, hopefully I can get some advice from experienced travelers.

I've been looking at utility conversions and here's the deal;

I have a 6X14 V nose single axel, ramp and RV doors. I got this trailer initially to haul my 1800 Trike and it came with strips on the walls that different attachment hook into, these are used to secure a load and there are a 3 baskets that are attached to the wall with slide in fasteners. It's easy to remove the baskets.

I want to convert it so that I can camp in it as well as haul my trike. Interior room is not a concern so long as my 52" wide trike will fit.

The interior plywood walls are in like new condition and I really don't want to tear the plywood out to insulate. 1. I'm an old phart and I'm lazy. 2. I'm not concerned with the additional space taken and 3. I want to leave those strips on the walls for securing a load.

Homes are built with plywood sheathing under the exterior siding, then insulated then with sheetrock, what I'd rather do is put foam insulation over the plywood, then cover that with beadboard on the lower section of the wall and use a PVC coated canvas to cover the upper walls and ceiling.

The canvas is from a large Army tent, in new condition. I can basically upholster the walls leaving the loading strips and still put my baskets up.

I can cover the RV door with insulation and upholster it, same with the ramp door but I may just put plywood over the insulation to drive up on.

I haven't seen anyone insulate over the plywood and then recover the insulation. There will be more weight with my method but nothing that significant.

From there I'll put a small galley up front, two wall beds or just two cots. I'll use a fridge and a solar generator for power with about 600 watts on the roof. Heat will be propane and I'll have a 5000 btu AC unit. I will also be installing two small RV windows.

Hopefully, you all can advise, what issue do you think there would be????

Welcome aboard.
There is a dead space behind the ply, yes? what about using an expanding foam to fill those dead spaces and then you only need to upholster your walls and don't lose any space to rigid insulation.

+1 on expanding foam. This will also make the walls very rigid and cut down on sound transmission.

Log in every time, site is kinda weird, but OK. Hope this works.

Thanks for the replies, not sure about the spray foam, the space between the aluminum sides and the plywood was going to be left as it is, there is a gap between the outer siding and the plywood, heat is probably the biggest enemy, the air space should be rising up under the exterior panel to exhaust from the vents. Sorry I see I didn't mention exterior vents along the sides.

I'm thinking that the inside can be sealed up, spray foam in the cracks and places where solid foam sheets can't cover.

I guess my real concern is moisture build up inside.

JasenC wrote:Welcome aboard.
There is a dead space behind the ply, yes? what about using an expanding foam to fill those dead spaces and then you only need to upholster your walls and don't lose any space to rigid insulation.

Thank you.

Years back I did a custom Van and used spray foam. That makes sense to fill the gap between the plywood and metal siding, but I'm afraid that would be much more work than striping the ply out.

Thinking out loud on the keyboard;

The spray foam, Great Stuff, would need to be applied from the inside, that would mean drilling small holes in the ply along a grid determined by the likely expansion area of the foam. I would think a small hole would need to be at least in every square foot.

The foam that I've used is pretty hard after it expands and dries. It also builds up a bit of pressure as it expands. If you try to fill a large cavity the foam falls into a cavity and sticks to a side, it may not reach the bottom of that cavity. It then begins to expand quickly and you'd end up with pockets of uninsulated areas inside that you couldn't see. I think I'd make a real mess of it trying to shoot foam in from the top. So the grid method would be best.

The pressure built up by the expansion will also push on the aluminum sides, these trailers use pretty thin stuff and the sides are a bit wavy as they sit, I would think the expansion would cause the outer skin to be deformed or more wavy, although the outer skins would be more solid. That pressure will certainly be enough to crack and pop lose the 1/8th inch trim on the walls, I cracked auto trim in the Van job so I know if you're not careful you can have another mess.

My trailer has about 324 sq ft of walls and ceiling, the space between the ply to the metal siding will be 1 1/2 inch being the size of the studs. That's nearly 70,000 cubic inches, 1 can of Great Stuf fills approx. 1,000 cubic inches, that's 70 cans @ $6.00= $420.00

Next issue, wiring; the trailer has wiring for lights in that space between the ply and the outer skin, I have no idea where they ran the wiring. Spraying the foam in on a grid system will cover wiring, with luck it wouldn't cause a lose connection.

I would think foil backed insulation board has a greater R value than the same thickness of Great Stuff.

Now, with that inch and a half air space between the interior ply and the outer skin there are advantages.

If there was a leak and water got inside that space it would dry out before causing water damage on the ply, at least a better chance of drying out. Great Stuff or foam insulation will trap moisture.

The space can be used to fish wiring for the roof solar, for outlets and switches. That air space also cuts down on heat transfer from the outer metal wall directly on the insulation.

Which brings us back to the original questions of insulating over the interior ply and then covering the insulation.

It would be quicker, less labor and least expensive. (I already have some beadboard and wall materials).

A camper is not a house but can be a home. Thinking of interior moisture from cooking and propane heat, I don't think this would be an issue for this PVC canvas or beadboard inside.

Is there something I'm missing about this concept?

Thanks again!

I'm also thinking out loud.
I was thinking of the boat stuff that you calculate the volume to fill, mix it up and pour it in. You could come down a couple feet from the ceiling, pour it in and slap some duct tape over the hole before it expanded that high. You'd want a place for it to escape if you had a little to much, hence the dust tape.

Thank you, yes there are several "spray foam" types, they all expand.

So, is anyone familiar with using solid foam board over the plywood?

Vnose wrote:So, is anyone familiar with using solid foam board over the plywood?

I don't think I have heard of anyone doing that.

One other benefit of actually taking the time to pull down the plywood is that you get to see what is behind it. Almost without exception when I have read a cargo trailer conversion thread where the plywood is removed the 'narrator' notes that there is pavement visible from inside the trailer. Sometimes quite a bit. This is to say that cargo trailers tend to be built for a certain type of use where fit and finish are not necessarily a top priority and in the manufacturing process it is common to have gaps, at times large ones, between the floor and walls. Having the plywood out of the way will give you an opportunity to observe and fix that issue. You can also inspect the wiring in that space, often quality control can be lacking there as well.

Yes, I agree on the points you're making.

rjgimp wrote:

Vnose wrote:So, is anyone familiar with using solid foam board over the plywood?

I don't think I have heard of anyone doing that.

One other benefit of actually taking the time to pull down the plywood is that you get to see what is behind it. Almost without exception when I have read a cargo trailer conversion thread where the plywood is removed the 'narrator' notes that there is pavement visible from inside the trailer. Sometimes quite a bit. This is to say that cargo trailers tend to be built for a certain type of use where fit and finish are not necessarily a top priority and in the manufacturing process it is common to have gaps, at times large ones, between the floor and walls. Having the plywood out of the way will give you an opportunity to observe and fix that issue. You can also inspect the wiring in that space, often quality control can be lacking there as well.

Totally agree, cargo trailers weren't built initially to live in, even if they do go off the line as a camper toy hauler the construction detail is usually pretty shabby.

As to those spaces at the bottom of the wall on the outside of the inner wall, the exterior metal is applied outside of the metal frame and the inner wall is on the inside of the frame. That should give me about an inch top and bottom.

That gap has a few advantages; first the air circulating between the ply and metal allows the wood to dry if it gets wet. That air gap also allows cooler air from the bottom to rise and escape at the top through vents. The hot metal is not touching the wood walls passing heat directly to the wood walls. Air is the best insulator, the foam material isn't the insulation itself, foam traps air inside it's structure that gives it insulative qualities, the thicker the foam the more air that is trapped. That gap also allows condensation to drip out if that should occur when humidity and dew point are close to the same.

If you were to look at the bottom of the siding on a house you'll find gaps between the siding and the exterior sheathing. While you probably don't have an inch all along the bottom the fact that air can reach the exterior sheathing keeps it dryer and prevents rot.

For those who have owned travel trailers with wood framing and sheathing, they know after years in the weather they will have rotten wood and much of that is due to an exterior solid surface, be it more wood, metal, fiberglass or even PVC is applied in contact with the sheathing.

At this point I'll simply say that my approach is to build an interior with foam, the interior wall will be sealed inside at the floor and ceiling, what air or temperature condition exists outside of the foam inner walls is really irrelevant. Inside temps will be regulated by opening windows or heat and A/C.

Going further with upholstered inner walls still allows air between the canvas and the foam surface. The PVC will be glued to half inch upholstery foam as a backing and glued to the foam board in spots, not over the full surface. Two reasons you don't want full coverage, 1. air saves the foam backing and 2. it is a heavy material that can contract and relax without friction on the surfaces.

This PVC coated canvas, standing as a tent alone can be heated and cooled even in the most extreme conditions, after all it's a military tent.

As to the trailer wiring, this won't be the first trailer I've rewired if and when that is required, for now it works and it will remain undisturbed.

Interior wiring will be run through PVC pipe and outlet boxes, water tight, screwed down on the lower wall base. Interior ceiling wire is exposed as there is no ceiling, just a center strip of ply.

I'm not opposed to spay foam, I plan on using it under the trailer floor filling gaps between foam board and at wall penetrations.

When I asked my question initially I knew this approach was not customary. I believe that this approach will be superior to the usual and customary, but this is also a unique situation using unconventional interior materials.

What it really comes down to is a military ten inside a cargo trailer that has additional insulation. On the inside I will have roll up canvas that can cover in rear ramp door and side door if needed. Using bead board 24 inches high simply dresses up the inner tent along with a valance at the walls and ceiling.

This method will also save me a good 10 days of labor, I'm older and slower than most builders I'm sure.

BTW, if you're wondering, the ramp door provides a patio that can also be enclosed with this canvas, weather permitting.

Not much progress due to this really hot weather!

I pulled the wood trim ply off the plywood walls, that revealed the seams where plywood was butted together, they did a very tight job of it except at the front of the V, about a quarter inch gap.

I did a simple test looking for cracks around the ceiling, floor and walls by turning some 12 volt driving lights on inside pointing toward suspect areas. I checked carefully all over the outside looking for light shinning through at night, no light went through any wall joints. Underneath at the V nose some light was making it through toward the bottom at the frame. That tells me that inside gap needs to be caulked and covered.

The light test tells me there are no large gaps, doesn't mean that it is air tight, it's not, but my garden hose tells me it is somewhat water tight, at least on the roof and at the exterior of the top of the wall. The roof trim was caulked by the manufacture, I'll be installing solar later on and I'll caulk the exterior joints again.

The floor is covered with a garage grade flooring, it will remain and I'll insulate from underneath then cover that insulation with sheeting.

I spoke to a structural engineer, I told him my plan and he said my method was actually better than pressing insulation against the aluminum sheeting and that the issue was that I would be losing a bit up interior space. After I told him how heavy the canvas was he thought I should use a solid wall covering and not use the canvas.

Okay, so that part of the plan may well be changed, after all he knows more than I do about building stuff.

That means I'll lose a little more interior space but I'll still have plenty of room for the trike, two beds, a poop pot and a kitchen area with a fridge.

JasenC wrote:I'm also thinking out loud.
I was thinking of the boat stuff that you calculate the volume to fill, mix it up and pour it in. You could come down a couple feet from the ceiling, pour it in and slap some duct tape over the hole before it expanded that high. You'd want a place for it to escape if you had a little to much, hence the dust tape.

I know a guy doing just this. You don't wish to under fill, so pouring enough to fill just over is going to be trial & error thing according to where you live. Rather hard to get it just right..

I use XPS panels and since you already have an outside skin in place, glue the panel to it. Removing your inside plywood carefully to reuse, glue that again to the foam. Easy/peasy!

I did fiberglass outside and plywood inside. Next time I will rebuild the panels first and use them as structural. In your case structural exists. Can't get much easier!

Adhesive choice is the concern. No matter what I say I used or anyone else, test it first! Be sure it works well in your climate and something you are comfortable working with. XPS foam seems to like epoxy resin as well as plywood does. It's what I use. I do like to perforate the XPS with a roller (bees wax remover roller) and have good luck with this.

Hope something here helps..

I'm pickin up what you're puttin down.

I just ran across XPS adhesive caulking, Loctite PL300 foamboard. I may pick up a tube and play with it a little, need to make sure is not to firm/thick and will easily smoosh out flat.

I used the PL300 some and it's not great for laminating.

Directions say to apply 1/4 inch vertical beads 12 inches apart. (This makes sense for the intended indoor application where you are going to hang wall board over it using mechanical means and you aren't trying to create a structural panel, so might work fine for you.) But if trying to create a SIP and done this way you can't really squeeze the foam into intimate contact with the substrate. What results are vertical voids, or chimneys, that allow air to move behind the foam and cure the adhesive to a rubbery caulk like consistency. Not very structural.

I used a notched trowel to get a smaller bead and more uniform coverage, but this had the effect of letting the edges cure first, sealing off the field so it never cured.

Next I shallow kerfed the foam, not for bending, but to provide air chimneys to allow the field to cure, and used the same notched trowel method. That worked, but it would have been so much easier, stronger, and probably no more expensive to have just used slightly thickened epoxy.

@KC Studly, thanks for the comments, I didn't follow the "curve edges" were you talking about the curved edge on foam sheets that fit in to another sheet, a male-female abutment?

@RJ Howell, thank you for the tip on XPS panels, that may be a better way to go, seems it would make the project go faster too. So, where do you get them and how are they on cost?

@JasenC, thanks, I've heard about PL 300, have you ever tried the 3M spray, I've had good luck with that.

Yesterday was a cool day at 98, I stepped inside the trailer thinking it would be an oven and was surprised that it was actually cooler inside. The trailer is silver and while it was warm to the touch on the outside, the inside plywood walls were not as warm. I suppose that air gap between the aluminum siding and the interior plywood helps keep the heat down. Today it's going to be 101 and hotter later through the week, I'll see if I can find a thermometer and check the difference as it sits.

I've been planning to fit a bathroom inside toward the front. After researching Bob's Cheap RV Living series on YouTube it seems most prefer to keep showers and the poop detail outside. I have a ramp door to the rear so that will make a patio and my 10X10 straight legged pop up tent can cover it, might just use the tent for the bathroom area. I certainly don't want holding tanks of any kind. 4-5 gallon water jugs should take care of my needs. Come to think of it, I have several water containers, if I filled up everything and carried them in the F-150, it could be about 42 gallons!