Teardrops n Tiny Travel Trailers

This comes up from time to time, but I'll do the old song and dance again.

How much you can cantilever your walls and floor really all depends on how well your bulkhead and end walls are tied in to your side walls and floor. On a camper that overhangs the frame rails and covers the wheels, it is actually the side walls that are holding the edges of the floor up; and the bulkhead(s), front and rear walls hold up the side walls. The floor only needs to be stiff enough to bridge between trailer side frame and cabin wall, which is generally a shorter distance than in between trailer xmbrs. The walls have the deepest vertical section, so longitudinally they are the stiffest beams in the entire structure. The trailer frame and floor have the shortest section, so they are the most flexible (if left unsupported by stiffening bulkheads, front and rear walls and cabinets). The walls, bulkheads, cabinets (if made integral as stiffening structure) and roof (yes the roof) stiffen the cabin structure, stabilizing the walls so that they don't buckle and can stiffen the trailer frame.

Just making the floor thicker out of solid plywood is a waste of weight. Are you even going to be walking that close to the walls? Consider building the floor up out of thinner skins and foam core; the depth of section adds stiffness by pushing the outer fibers further apart; the outer most fibers (the skins) take most of the tension and compression loads from any bending, while the middle fibers don't do much but hold the outer fibers apart, which the foam is suitable for and much lighter. In a built up floor, if you will be walking on it you probably want the upper floor skin to be a bit thicker, maybe 3/8 inch, but the under side can be thinner to save weight. If weight is a real concern, consider using the thicker ply only in areas that will actually be walked on.

If you want to cantilever off of the front of the trailer frame it would be a good idea to have a forward cabinet with structural face frame, or a low shear wall built into a bench face/under seat storage bin, etc. Same thing in the rear, if you aren't doing a TD style bulkhead, add shear walls under your bed frame, storage lockers, upper cabinet face frame (think trestle) or a structural arch to bridge between the walls. You are not building a stone pyramid where everything gets stacked on top of the thing below it, resulting in a massive structure; you are building a bird cage Maserati (a classic race car that had no traditional chassis, just small tubes welded in a structural array of triangulation) where the sum of all of the small structural parts tie together into a very light yet rigid structure.

With a properly designed cabin you can cantilever quite a bit without having to add any outrigger structure at all; up to 1 foot is pretty common.

I recommend that you read a few more successful build threads of similar size to your project before making any decisions.

Here’s the bottom braces we added to our OSB floor to support the Foam cabin structure … which is pretty Light .

Thanks to everyone and their suggestions and ideas. We have taken many of your ideas and forged them into a plan. KC, you in particular have done an excellent job of succinctly describing what I thought I understood from the hours and hours of reading about foamies in the past year. I appreciate your willingness to describe the support process one more time! More to come after our workday and experiments.

So what we were hoping for really worked!! What we found were heavy duty steel brackets (the kind sold for supporting granite countertops) We are using 7 of them--2 in the back, one on each side behind the wheels, 2 in the front side where the door will be and one on the other side front. A pair of them are rated for 500# of weight which is beyond anything we would ever need. All simply done for a total of 25# additional weight and no additional height. We are still using the PVC in the front because it is well supported by the 1/2 inch c-channel attached to the cross pieces on the tow rail. This adds support to the tow rail which seems to be a weak link on some of these trailers. I wish we had found these brackets earlier! Pictures to follow. Thanks for the ideas that led to this!!

Jana, really happy you figured out an alternative to the PVC. We are going to start a build this fall, and we also live in ABQ. I'll be watching your build closely. Best of luck!

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I look forward to seeing your pictures too. I kept thinking about your build and couldn't figure out the details on how it was constructed even though you described it in detail. I'm glad it is working out and that you don't have to tear apart and rebuild any of it.

Don, actually we did get rid of 75% of the PVC. Your picture of the welded steel extensions was the inspiration for our modifications. Since we do not have welding skills and out trailer was bolted together from a kit, I researched heavy duty brackets and found steel ones that were designed to support countertops. We ordered 3 and we installed them today--bolted into place much like your welded extensions. We ordered 5 more which will come in next week. We also modified the floor sandwiching the foam between 2 layers of plywood. I wish we would have found the brackets earlier--they would have saved us a lot of work!! We worked on the layers of the floor and have holes drilled for the bolts. Can't take the floor off to take pictures of the supports until we glue the layers.

BBQBOY60, since you are in the neighborhood, when we get further along on our build, you would be welcome to stop by and see it--if you would like.

Thanks Jana! Ill pm you once you're further along.

Cheers,

Bobby

Jana wrote:BBQBOY60, since you are in the neighborhood, when we get further along on our build, you would be welcome to stop by and see it--if you would like.

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Jana, that's interesting about the bolt on brackets. Great find!
As far as re-doing things it's just water under the bridge as they say. Now you're past that and making good progress! That's a good feeling.

I can't weld either and luckily I found the camper with the frame already done. Late 1960's vintage.

We worked hard this week. We got the floor brackets on--a very solid improvement over the earlier plan. The floor layers got waterproofed and the bottom layer was painted with Black beauty--an asphalt paint. We used flat PVC as shims to even the floor. Half of the floor is layered and glued. Tomorrow we hope to finish the floor and begin planning for walls and furniture supports. And here are pictures!

So last week we got the side walls glued together and the shape cut. We are ready to work on the bed frame and benches over the wheel wells. Also marking for windows and doors. Still deciding about spars for the roof. People have been all over the board about spars--use wood, use foam, make bulkhead cabinets, use wood with ceiling fans or use metal to tie in screws. Lots of different ways. If my trailer is approximately 6'4" x 11' will I need at least a few wooden spars in addition to bulkhead cabinets? I will be supporting a ceiling fan. I will be using a commercial door and 2 windows. I will use wood for window framing since they are compression windows. I am open to all suggestions. Pictures to follow.

Just a thought on spars … many ways you can do it … basically your choice … And as we all know , although very basic Foamies have proven themselves, it’s still best to err on the side of “overbuilding". Do what You think You need !!! You have to camp in it ...