Canned ham construction?

[lstyles]

I am pretty sure I am going to build a canned ham soon...probably about 13ft long by 80" wide. The frame will either be from an old pop up trailer or from aluminum bolt together. I am trying to go as lightweight as possible with this build. I see a lot of posts that say most first time builders over build. I definitely don't want to do that but am concerned that the larger size (and height) of the canned ham design may need more support than a teardrop. I have looked at some of the construction techniques and some of the builder threads for ideas but wanted to get some input into a floor structure and the wall structure. For the flooring it seems like a fir-framed structure with plywood top set on the metal frame would be the way to go with insulation (?thickness) under the plywood between the wood frame members. What size frame members and thickness of ply would people suggest? Similarly I want to insulate the walls and it seems like a sandwich construction is a good approach. Maybe an inner skin of 1/8" ply with 1" stiff insulation (too much ?too little?) with aluminum as outer skin. I plan on painting the outside aluminum or buying pre-painted aluminum (will need to get more information about that later). Again, what size framing should I be using and will 1/8" ply be enough? I want to keep things lite and money isn't a huge issue so if there are more expensive alternatives that would be lighter I would like to hear about them.
Thanks in advance,
Lori

[josephhanson]

I have a "standie" that I built with 1/8 luan ply inside and outside, with the exterior covered with filon. The frame is minimal, I looked at manufactured campers and went lightwight as they did. My walls have 1" foam insulation glued to the 1/8 luan, I believe that's where the strength comes from. My wall studs are 1" X 1-1/4" (2x4's cut down). I only have studs where I thought there would be some stress, around windows, doors, or where items inside needed support. All studs, plywood, insulation, etc are glued together using PL glue. That glue is stronger than the wood it's glued to.
I hope this helps.
Joe

[aggie79]

Lori,

For your floor, I would probably use plywood on both sides of your framing. Using a second, "road side" sheet of plywood adds considerable strength. It doesn't need to be thick - 1/8" would be more than sufficient. For the interior side, I would use at least 1/4" for the floor.

For your sidewall framing, be sure to have framing where you need to fasten the aluminum.

Take care,
Tom

[bbarry]

I personally don't think there's any need to have a second wooden frame sitting on top of a full metal frame. If lightweight is what you want, bolt your ply floor directly to the metal frame and attach the sidewalls using nailers above or below the floor.

[lstyles]

Thanks for the comments. I had thought about just a solid floor and no insulation but was afraid that might leave it too cold off the ground like that. I guess I could put insulation between the frame members and attach directly to the solid ply floor? What thickness of ply would you think I would need if going this route?
I dont know much about this filon stuff. Actually I don't know much about exterior aluminum either. It seems the filon must be attached to something. I like that I can build the frame and put on the inner skin and attach it to floor and leave the exterior unskinned until I am ready to put on aluminum. That way I full access for installing/attaching furniture, wiring etc as I go along. Can one do something similar with filon? By that I mean just attach to the underlying frame or does it lack the rigidity it needs. Where does one go to see/purchase filon?
thanks again,
Lori

[lstyles]

One more question:
What is a nailer? You mention this in your post. Is that just a piece of wood attached at the edge of the floor for the wall to attach to?
thanks,
Lori

[bbarry]

Thanks for the comments. I had thought about just a solid floor and no insulation but was afraid that might leave it too cold off the ground like that. I guess I could put insulation between the frame members and attach directly to the solid ply floor? What thickness of ply would you think I would need if going this route?
I dont know much about this filon stuff. Actually I don't know much about exterior aluminum either. It seems the filon must be attached to something. I like that I can build the frame and put on the inner skin and attach it to floor and leave the exterior unskinned until I am ready to put on aluminum. That way I full access for installing/attaching furniture, wiring etc as I go along. Can one do something similar with filon? By that I mean just attach to the underlying frame or does it lack the rigidity it needs. Where does one go to see/purchase filon?
thanks again,
Lori

If you are indeed going to be camping in the dead of winter, I'd probably make the floor insulation a priority. Otherwise, for normal three season camping, you could probably get by without it (my teardrop doesn't have any insulation in the floors and it's been fine down to about 40 degrees with no heater. That being said, it would be a piece of cake to attach foam board to the bottom of the floor after bolting to the trailer frame.

As for what ply to use for the floor, you may get a variety of opinions. In a standy, it's more important to have a sturdy floor as you are standing on it and your weight is concentrated into smaller areas. I used 3/4 on my teardrop and it would been overkill had I not extended my floor beyond the metal frame. For your application, if you are using a pop up frame and the framing is closely spaced, you could probably get away with 1/2 or 5/8...just depends on the space you are spanning.

I don't know anything about filon, maybe somebody else can chime in. You are exactly right on the nailer...typically a 2x2. The only downside to this is that it's usually on top of the floor and crates a little bump on the inside corner of your living space.

[angib]

Lori, you are mostly describing 'traditional' trailer construction and I suggest two information sources:

- The larger models in the 'Vintage Plans' link at the top of this page will show you how trailers were home-built many years ago and exactly the same construction would work today.

- The Glen-L trailer and truck camper plans have some good photo sets of building their designs, which are also mostly traditional with aluminium sheet exteriors over wood/ply interor skins:
http://www.glen-l.com/campers/sequoia-constr-1.html
http://www.glen-l.com/campers/fairhaven-constr-1.html

[lstyles]

Thanks for the links! I agree that my preference for construction looks pretty traditional. Is there an alternative that I might consider to make it more lightweight? Or are there newer materials which might enable me to make it lighter? I don't mind spending some extra cash in order to make it lighter weight. Am considering using Okume plywood as my understanding is that it is lighter but stronger (and more expensive). This is at least one way I might be able to spend a little extra cash and lighten things up???
thanks,
Lori

[angib]

Is there an alternative that I might consider to make it more lightweight?

No, I think if you look at the old plans you will see some very lightly built trailers - lighter than most of the teardrops on this forum.

Almost anything is strong enough overall to work as a trailer. By overall, I mean it won't blow off the chassis at speed or the roof collapse in the snow. Heavier construction mostly makes the body stronger locally - so if for example, you need to punch your trailer when you're angry without it being damaged*, you need to build it stronger and heavier than the old plans!

Using an aluminium exterior skin is the one place where 'traditional' trailer building is not that light - it will generally be lighter to use a plywood outer skin, as long as you keep the plywood thin. But then you have to protect/finish the plywood and that means quite a bit of work and time, which in a trailer-building company would be expensive, so they use aluminium or Filon (fiberglass).


*Hey, I've watched Hollywood films - Americans do this all the time.

[bbarry]

so if for example, you need to punch your trailer when you're angry without it being damaged*, you need to build it stronger and heavier than the old plans!

*Hey, I've watched Hollywood films - Americans do this all the time.

Whoa, whoa! If we're building to Hollywood standards, our trailers also need to be able to survive being hitched behind a 60s muscle car and jumped across a river with 7 cop cars in pursuit.

[Rock]

Lori,

If you look at the old Serro Scotty Sportsman (several here have them and I just bought a '64) they are less than 1,000 lbs. No potty/shower but barely a standy, stove/sink, sleeps 2 adults and 2 children.

As Andrew said many teardrops come in heavier than that. The great thing is you can build whatever you want but there is no need to re-invent the wheel.

Eric

[doug hodder]

I think that one of the things that people need to remember is that there is a big difference in what a home builder and a manufacturer can do. How you are "tooled up", budget, abilities and material purchases really effect your ability to build a light economical trailer. Throw enough money at it and you can probably get what you want, but you'll pay for it. Some materials may require tools or more money than planned so for many an alternative is in order. Usually, it involves more weight.

While many of us do indeed overbuild, a lot of it isn't all that bad. Most of the "home builders" are using much better adhesives, screws, materials etc...that many of the original manufacturers weren't using. I'll take some epoxy and screws over an air staple any day, however like Andrew mentioned...there are lots of very light trailers that have been built over the years.

I'm kinda wondering how they figured the weight on some of the older trailers. Steve E on his Scotty resto...used the existing Scotty frame, axle, skins, all the hardware etc..., and built exactly how it was originally done, same materials ...came in 400# over what was the POS (point of sale) weight, unloaded and no personal stuff. We're head scratching on that one. Maybe they stripped the cushions, battery, propane etc. out of them to make weight for the sales. Doug

[Rock]

That's good info Doug. I just took the weight in the literature for granted. To be honest a Sportsman looks like way more than a 1,000 lbs. The frame/axle/wheels have to be at least 400.

Mines not even here - still in the outlaws' barn. I'm not even gonna start on it until next winter. I'll have to get a before and after weight.

Eric

[angib]

I'm kinda wondering how they figured the weight on some of the older trailers.

The folks over at FiberglassRV with early Scamps and Bolers have GVWRs of 1000 pounds - but whenever they weight actual trailers they come out at 1400 pounds or so.

Maybe they looked at what a Chevrolet Vega could tow and quoted that as the weight.....? People nowadays seem to forget just how light (and small) smaller tow vehicles were in the past.