Teardrops n Tiny Travel Trailers

I'm wanting to build my first foamie. I've seen several build that are 48 inches wide, outside to outside, which would give in inside dimension of 44 inches. At 48 inches no stringers are required, just foam canvas. I'm sure there is a width limit for structural strength of foam and canvas. How wide can you go before stringers are required?

I would like a little more room inside. If I built one 64 inches wide outside, 60 inches inside, will the foam an canvas be enough to span the extra 16 inches width? Or will I need to adds some stringers?

On my son's foamie, which is 64" wide and 60" inside (2" foam walls), we used 1/8" lauan for the ceiling and 1 1/2" foam over the top. That was covered in PMF (10oz canvas). No stringers/spars needed. A bulkhead at 80" and cabinet frames at the foot of the bed plus shelving for the headboard is all the additional structure we installed.

Edit... I should mention that the curvature of the lauan as well as the bulkhead, footboard cabinets and headboard cabinets provide a good amount of support. The flat portion of my son's foamie roof is maybe 24" without framing. The lauan was braced on the flat section during foam install and when set the assembly became rigid. There's little air pressure on the flat surface while towing. However, if you add spars in that area all the better. We haven't had any issues with it so far and it is stored indoors so snow load isn't a factor.

I built from the inside out with a slight crown/arched radius in my roof profile, and in the beginning planned to use 5mm Okoume ply ceiling without spars. 64 wide with cabinet face frames front and rear, plus 2x cedar spars and bridging around the roof fan. When I put the ceiling ply up on the cabin for a dry fit I noticed that the ply sagged in the middle, under it's own weight, and did not maintain the desired profile.

I decided to glue the fan spars/frame and additional spars to the top of the ceiling prior to installing it on the cabin, which solved the sagging issue and gave me additional peace of mind for potential snow loading here in the northeast.

Now if you have a more pronounced roof arch and you apply canvas to the outside of your roof foam it would likely act as a "strecher" helping the foam bend around your profile and there would likely be no sagging because the foam is so light. Applying PMF to the inside after the fact would be a total pain, IMO. The load carrying ability would depend on several factors including: the thickness of the foam; weight of canvas; and radius of roof arch.

The one sided skin stretcher would strengthen the tension side, while allowing the compression side to compress during the bending process, possibly precluding the need for kerfs that would otherwise weaken the roof panel. If you were to skin both sides prior to installation it would resist bending too much, I think.

For a flat roof, even with 3 inch thick foam, I don't think I'd risk it. There is bound to be some, even a small amount of sagging (especially with even a modest amount if snow load) and the resulting puddling/pooling of rain/melt water would challenge most all methods of sealing.

I’m curious if you’ve started your build yet. I’m getting ready to build at 64” wide and am considering either just using a regular glued butt joint or else trying wood biscuits to strengthen the roof joints. I’ll also be using PMF which seems to add a fair amount of strength. My build will not have any roof rack or awning. Let me know what you chose to do. Thx

hybridfan wrote:I’m curious if you’ve started your build yet. I’m getting ready to build at 64” wide and am considering either just using a regular glued butt joint or else trying wood biscuits to strengthen the roof joints. I’ll also be using PMF which seems to add a fair amount of strength. My build will not have any roof rack or awning. Let me know what you chose to do. Thx

I started the build this spring, got all of the foam cut. I had another project come up and put the camper put on hold for the summer. It's about time to start on the camper again. I was planning to use a but joint with bamboo barbeque skewers every 6-8 inches or so for reinforcements. I was planning to overlap the canvas along the edges, which will also reinforce the joint.

I have not decided on stringers reinforcements yet. The first thing is to experiment with some canvas to see if PMF alone will be strong enough for the extra span. My concern is if the foam & canvas will be able to withstand the wind loads of going down the highway. I'm confidant it is strong enough for a 48" wide build, not sure if the extra width (64" wide) would be too much and cause the foam to fail.

I live in a zone that use to get 12” to 14” of snow in a night,
I need to add support and want a small arch to keep the water off,
I would like to, get stared on mine as well,
Too wide is when you need to add extra light’s, I did on my first.
I still have a lot to do on it, but like the back open until it isn’t.

Is it a mistake to go 1” narrower inside & is that enough to keep a mattress from moving ? say 59”
With 1-1/2” foam walls that’s (todays) plan

The only problem with having to compress a foam mattress into a narrow space, like an inch or two narrower than the mattress, is getting a fitted sheet on the mattress. And that isn't a biggie..
Otherwise I've had no problems.

My woodie is about 56.5" wide inside. I cut an inch off the 60" wide memory foam mattress and it fits real nice. Cutting was done with an electric carving knife.

Is it a mistake to go 1” narrower inside & is that enough to keep a mattress from moving ? say 59”

It won't be an issue.



:thumbs-up:

Tony

Carving knife it is for my king, now it won’t be open, that was easy
Two Fer, it’s way heavy.