Squareback #1

[knova]

Hi all,

I'm making a go at building a squareback camping trailer. Plenty of questions will be asked along the way so chime in if you feel like it. I think this project is going to be sort of slow going, but as of this post we (me, my wife, and my Uncle who is giving us critical help) have the metal frame built, welded, and painted. I'll probably end up posting more photos on my website, I'd like to keep this build journal as clean as possible. http://novaks.us/archives/116

We are starting with a Harbor freight 4x8 trailer. I built it mostly according to the instructions, left off the side brackets for 2x4 mounting. We kept it foldable at first but have since removed some of the other pieces that enable it to fold.

Welding prep:


Welding complete, painting it black. notice the 'storage caster' pieces were removed.


Painted, drying.



Here come some questions. I mocked up how I may be able to build out over the wheels easily (the goal is to turn the 4x8 frame into a 5x8 trailer). If I add 6" on either side, I was going to stack two 2x4s across to get me clearance above the wheels (fenders would be removed). Any concerns with this? I am going to sketch up a drawing of how this would work but here are some mockups with scrap 2x4s I did:


Side view of my framing mockup:

[knova]

Here is what I am thinking regarding the framing.



Put a 4x8 piece of 1/2" plywood down as a bed to build off of. Two stacked 2x4s going across the metal frame "short ways", basically rebuilding the crossmembers of the metal harbor freight frame. Insulate between those cross members. On top of the 2x4 frame, I will run two 8 ft 2x4s 'long ways' for support for the actual trailer bed.

There will be a 6" x 8ft gap on either side which will be missing a plywood bed, so I figured at that point I can flip the whole trailer over, cut some plywood to size to seal that, and seal the bottom with roofing tar or something similar.I'd probably have to work around the wheels and won't be able to insulate fully near the wheels. But I figure that's such a small portion of the overall bed that I won't lose too much temp that way.

Sorry if this is confusing, it makes sense in my head but kind of hard to draw / put into words. It may make more sense when I actually do it and show it through photos.

I know the consensus is using 2x4s is overkill, I just wanted to clarify i am only doing that to get clearance above the wheels without sacrificing interior space. The walls will be 1/4" plywood exterior with 1x4 stick framing, most likely. Not sure what I want to do for the interior wall yet but leaning towards 1/8" plywood.

[greygoos]

Ditch the 2 x 4's and turn some 1 by on their side. Less weight and if you want you can can cover with ply on both sides and insulate. You are making a sandwich and or torsion box.

[EZ]

Built a 8' X 5 1/2' base on a Harbor Freight trailer. I used 1 X 3's on their side and it allowed enough clearance over the tire to not require wheel wells. Ditch the HF fenders. Use 5/8" ply for the floor, paint the bottom (and top) with a couple coats of good 100% latex house paint for protection. You can add insulation to the bottom (glued with Locktite PL300 foamboard glue in caulk tubes - strong stuff!) and just leave it open on the bottom; they have been building campers that way for decades with insulation not nearly as tough as the pink stuff we have access to (3/4"). A 1 X 3 frame with plywood is supper strong and rigid, especially when bolted to a steel trailer frame.

Just my suggestion.......



Floor for new standie build in progress:


Good idea painting the trailer. I have one that I use to haul stuff and it is pink after less than 2 years.......

Ed

[knova]

Dig it. Thanks for the suggestions. Any concern with splitting the 1x3 when bolting to the trailer? Seems like a thin piece of wood to be bolting down.

And I forgot to mention, but yes the fenders are coming off. Kept them on for the ride between my uncle's house and my place.

RE: paint... I've seen the pics and was not interested in a pink frame, even if it is mostly going to be covered by wood walls in the end.

[swoody126]

already a coupla good suggestions above

i might consider a full width deck made of 2-sheets of 1/2" exterior plywood(not OSB in any form or fashion)

situate the sheets transversely w/ the seam across the center(no need for post fitting the pieces in front and behind the tires later which would mean more seams to seal and would IMHO weaken the structure)

this method will require 2 full sheets to begin with butt IMHO the increased integrity wil be worth the $$

make your perimeter frame w/ at least a 2x(standing on edge) across the center that you can screw/glue the center seam under easily

personally i make boats by framing/mocking everything up dry screwing only the edge joints (not snug just to locate) to the sides

once all the pieces are fitted and everything squared up n clamped in place i trace around ALL of the framing pieces on the inside of the bottom

next step is to remove the framing and pre-drill pilot holes everywhere i want a fastener coming up thru the bottom into the framing better insuring(i still miss sometimes) i hit the frame when the time comes for gluing n screwing the frame together permanently

w/ this method YOU would have the double thick cross member in the center for ease of screwing and hitting solid wood w/ those screws prior to securing the wooden floor to the metal trailer frame

how tall you choose to make your floor box is up to you

how much insulation you put in it is also up to you

my comments are primarily aimed at strengthining and simplifying the bottom outer layer of your floor structure

hope this makes sense

sw

[knova]

Thanks swoody126, I think that makes plenty of sense and seems to be an easier way to tackle the 'true floor' of the trailer.

[knova]

After months of 'analysis paralysis' i've started up work again. I cut out the plywood floor which will bolt directly to the metal frame. From there, I will build up using 2x4s for a subfloor which I can fill with insulation, and on top of that, another piece of plywood for the 'cabin floor'.

Next step is to use some spray on Bed liner for the plywood, just to give the bottom some extra water protection (even though it is marine grade plywood).

Edit - forgot to add. Question: should the metal wheel wells come off? I’m afraid of a rock kicking up and blowing through my plywood floor. Otherwise, the metal stays on, and I can build over it with the 2x4 frame / cabin floor.

[txcamper]

I used a similar solution on a 4' wide trailer to get a 5' base, page 2 shows it flipped over and the framing is a little more visible when I was adding insulation.

viewtopic.php?f=50&t=49566

[knova]

Made some progress yesterday with my friend Tyler who has a lot of experience doing carpentry. We framed up the bottom with 2x4 lumber attached to the plywood floor. This will leave an area to be insulated, and I'll then cover it with another layer of 1/2" plywood.

Next Steps:

• I need to seal up the plywood edges with some kind of epoxy.
• Drill a channel for any cabling I might have coming from the front where the battery will live (for lights and fan; trailer lighting is run underneath and is secured to the metal frame)
• Could use recommendations on how to build the back hatch. I'm not doing a galley, but we want a back hatch/door because we will store some things in the back of the trailer, plus it will be nice to have an entrance covered with an awning - the rear hatch should act as a cover
• going to order two premade doors because I don't feel like messing around with making my own.

[working on it]

* I built (build, built, am building, will continue building....) a squareback TTT, starting 10-1-2011 and always modifying since. My frame was smaller than a HF, but I expanded it to 50' x 97.5" so I could build a 4'x8' (the traditional size, I thought), but now wish I had made it 5'x10' or 6'x12', for the added room. As is, I've crammed a lot inside, and even more outside (never leave home without more than you need!). And, I carry so much gear in my galley, that it's not a galley but just storage space, as you wish to have on yours.

* On a squareback, a rear hatch can be simply a solid sheet of plywood hung vertically from the roof, and sealed with bulb-seals all around the perimeter. I used a 48"W x 49.5"H piece for mine. The "galley" area is 46.5" wide, 48" tall, and 22" deep, while the cabin area is 46.5" wide, 48" tall, and 73.25" long (twin mattress will fit). Perfect for me, solo camping.

* My doors were simply the cut-outs from the sides, cut at the same time, and then trimmed, and edges sanded to easily open and sit flush without offset hinges (I mad an interior door jamb for them to close against, while compressing automotive seals.

* I ran wiring under the frame (battery in the tonguebox, master cut-off in the galley), then thru the rear bulkhead into the cabin, to a large key cabinet used as 12vdc fusebox, and split into forward and rear circuits for the 110vac. The forward 110vac wiring (and 12vdc for car stereo & computer case fans on my front vents) is run inside a grey wire loom in plain sight along the ceiling/wall interface (so I can easily fix any loose or compromised wiring). I have no insulation, so there wasn't a need to cover it.

* I used the "mix" of polyurethane and paint thinner lavishly before multiple coats of outdoor enamel eventually covered the plywood. So, all wood is thoroughly "plasticized" and water-resistant. Even so, since I have most of the plywood edges exposed, I tripled the protection by using black enamel on all edges (re-touched before camping each year), except on the roof/front slope area, which was sealed with PL adhesive before being painted. I never had much liking for epoxy nor fiberglass, so the polyurethane/oil-based enamel method was the way I went. Seven summers after painting, there's been no leaking, swelling, nor de-lamination anywhere.

* Additionally: I notice that your axle centerline is nearly at the center of your floorplan...you're going to have to carefully move most of the weight forward of the CL, or your trailer will not track nicely. My tongueweight was too light at first, until I found the right-sized tongue-box I needed (had always intended to use, but couldn't find before my first trip), and moved the battery and a lot of other weight there. Even so, I had to use work-around solutions before I got the balance where I wanted it. Read my posts to see my struggles (there never was a build journal).

[knova]

Thank you working on it, your posts are always a wealth of information. Since we have similar build profiles I’ve scoured through a lot of your posts during my prep/planning.

The plan is to get my tongue weight right, as I did end up making the mistake of not moving the axel. Oops. There will be plenty of test drives in the local parking lot to ensure it tracks correctly, albeit it at low speeds. Eventually I’d like to look into the axel-less options out there, last I looked they were just a little too pricey for me at the moment.

There has been a lot of work done since my last post, I need to get better at updating this build log. Once I’m on my home computer I’ll post some new pics.

Next steps currently:
-electrical wiring
-roof insulation, followed by roof installation
-sealing & painting

I’m torn on what I want to do with the storage area, so I may end up adding that afterwards - I know it isn’t as easy to do after the fact. But I’d almost like to know what I need before I add it, if that makes sense.