Weight difference of foam vs plywood

[SteveW]

Foam, when given an appropriate skin, is extremely strong. Aluminum w/ spars or a foam/fiberglass...which one would you rather have if a 180 pound man jumped on top of your camper?

http://www.youtube.com/watch?v=7eUt0YnNF3o

[Larry C]

Now there is a key word in this whole weight loss drive is structural integrity. If you had a foot of snow fall on your foam structure can it withstand the added weight on top of it? DOT and OSHA standards are in place for many reasons and safety being the number one thing. That's why on the exterior shell surface is where my greatest concerns lie for stiffness and strength of the overall structure. If a person couldn't lay or walk on the roof of the camper, I'd sure not be very comforted sleeping in it. What if a storm blew through and took a tree limb onto the structure? Lots of things to ponder more than light and cheap in life.

Steve,
Have you ever seen how lightly many travel trailers are built. I helped a friend dismantle one to get some of the parts he wanted. The frame was 1" square wood placed 12-16" apart even around doors. It had 1/8" paneling on the inside and just the aluminum skin on the outside. Between the 1" studs was fiberglass insulation. I don't think anyone could walk on this roof without falling through.
Also, I witnessed the aftermath of an accident where a travel trailer being towed went off the highway, down an embankment and rolled over. It was difficult to tell what was actually there. Other than the chassis, the rest of the entire TT could have fit in a couple of 55 gal drums!
Look at an aluminum PU camper shell. The ribs are spaced 2' apart, the walls are glass or plastic, and don't try walking on top of one, but they hold up for years traveling down the highways at 80MPH.
If a tree limb falls on my tent, house, car, or teardrop, it's probably going to have the same result.

[linuxmanxxx]

Yes and the point is we aren't the TT industry and can build light yet very strong compared to the crap they put out. I'd feel safe of a branch falling on mine unless it was the actual whole tree and then I'd be concerned. But think of just foam skinned in and out with canvas wouldn't stop a small branch if it fell on it during a storm and storms are possible when out and about camping.

I just want people to think at least about the minimum level of whatifs before they jump on board of any type of build and realize the risks involved with focusing on weight reduction and giving up structural strength with the weight loss.

[GPW]

After my experience with limbs and a commercial TT , I’m all for a good roof ... No reason it can’t be light and strong ..
Please don’t get me started on the commercial TTs which are neither light nor strong ... (POS)

[pete42]

been camping for over 50 years from tents to travel trailers.
never once in those 50 years has a limb fallen on me, nor have I shot frozen turkeys at any of the trailers or tents.
If one were to really use a trailer in which he would feel safe from falling objects,
meteorites come to mind, it would be built in Lima Ohio where they build tanks for the army.
If you are so worried about falling limbs, hailstones or what ever stay home don't build
but then I have read about the dreaded blue ice from passing airliners going through roofs of houses.
build something don't live your life in fear..............

Pete

[GPW]

Same odds as winning the Lottery ....

[Larry C]

I just want it strong enoygh to keep the "Walkers" out

[linuxmanxxx]

I live in texas where hail storms are a huge reality and pop in nothing flat so mock that all you want but we are talking about kids safety as well if you ut your kids in your camper. Would you send your kids to school in a tent or a subsafe structure? Same chances of something happening there as in a camper.

My point is there are consequences to structural integrity being traded off for weight and towability and if that one branch did fall and kill someone you strongly urged to ditch it all and go canvas and foam how you gonna feel? You gonna blame it on the foam or canvas when they weren't suggesting to use themselves to build?

If you get caught in one in a blizzard and 3 ft of snow is piled on it and it collapses on someone inside was the weight savings worth getting smothered to death? My point is consider the environment and try and make it as safe as possible. If its just you in it and you don't care about overall safety is one thing but if others are involved they are at risk as well.

[GPW]

Now I’m thinking I’ll just buy an old Army Tank instead ..

[eaglesdare]

i will tolerate a good discussion, but i will not tolerate an arguement. not here on the foamies threads.

everyone take a deep breath and back off for awhile!

to some, a foamie is a great idea, period. to others it is not, period. i do not think we are going to change each others opinions, or beliefs.

things do happen, a branch can fall while camping in a tent, rv, td, anything. a bear can break into a car, tent, rv if he wants to. a car can run into your house. hail storms can damage vehicles. things do happen. build your td/ttt how you want with regards to safty, towability, and whatever else you choose for priorities.

again, i will not let bickering take place here in the foamie section, period. i don't care who it comes from (well except mike, cuz he's the boss).

the points have been made on both sides here.
this is the first, final and only warning i will put out here. i will close this thread immediately if there is one more post about the issue. please stay on topic.

[StPatron]

Katozzi,

You MAY realize some weight savings by using insulating foam as a structural component but you need to aware of the risks involved. Plywood is a tried and tested building material that has been used in teardrop and tiny travel trailer building for many years. It is a true structural material. The foams referenced lately are not, they are designed only for use as insulation. Structural integrity, from an engineer's viewpoint, is a very important consideration... much more so than cost savings or aesthetics.

Both materials are readily available, neither are exotic. Costs are comparable.

If you are willing to accept all the risks of a lightweight, more fragile structure that's still in the very early stages of experimental development... go with foam. Or, you can build light and still use plywood. Many examples here on the forum.

[loaderman]

Why not have lightweight, strong, and inexpensive? The foamie idea is an old one, a new look at old building methods. Very durable canvass boats have been built.
It is a stressed skin panel. The same as SIPs (Structural Insulated Panels) in house building. The main strength comes not from the foam, but rather from the wrapping of the canvas, the sock efffect.

We need someone to build a Foamie and test the strength scientifically.

[GPW]

We do have a Real Engineer on board now to splain’ it all ...

[S. Heisley]

We do have a Real Engineer on board now to splain’ it all ...

He's still standing on the shore! Let him get his feet wet. Being a mechanical engineer doesn't mean he knows everything and we don't want to scare him away by expecting a lot out of him immediately. I used to be very familiar with a mechanical engineer and he could tell you a lot about an engine or steam but I doubt he could say jack about foam unless he worked at becoming familiar with it, especially the way you're using it. …Patience, Grasshoppah.

Putting this entire thread in perspective, my thoughts are that the foamies are evolving and getting better with time and all will prove itself in the end.

Foamie Pioneers, please remember: Many scoffed at Noah when he was building the Ark. I follow your progress with interest and cheer from above the race track.

[S. Heisley]

I live in texas where hail storms are a huge reality and pop in nothing flat so mock that all you want but we are talking about kids safety as well if you ut your kids in your camper. Would you send your kids to school in a tent or a subsafe structure? Same chances of something happening there as in a camper. Yup! It would probably get dimpled pretty well. So does the metal on a car roof.

My point is there are consequences to structural integrity being traded off for weight and towability and if that one branch did fall and kill someone you strongly urged to ditch it all and go canvas and foam how you gonna feel? You gonna blame it on the foam or canvas when they weren't suggesting to use themselves to build? I've seen a tree branch fall through a house roof! The foam might help cradle a person.

If you get caught in one in a blizzard and 3 ft of snow is piled on it and it collapses on someone inside was the weight savings worth getting smothered to death? My point is consider the environment and try and make it as safe as possible. If its just you in it and you don't care about overall safety is one thing but if others are involved they are at risk as well. I wouldn't want anybody to get stuck in a blizzard with 3 ft. of snow on their roof! ...Even in a plywood trailer! Anybody that does that might be a little

You're absolutely correct when you say use common sense. Right now, foamies are one step above a tent and that's okay, as long as people recognize that the final outcome of what can be accomplished may not yet be realized. Further, since riding in a camping trailer is against the law in most (all?) places, from a health standpoint, a foamie becomes the equivalent of a rolling tent, with the additional advantages of:
1) It's already erected when you get to the camp ground.
2) The comfortable bed is already made (hopefully).
3) It has more insulation than nylon or canvas alone.

Some people may not be ready commit to the work and/or expense of a plywood trailer. For them, this may be the first step or an answer to their need. If we discourage this, we discourage experimentation and research into what could be in our future. One does not know what the end result will be until we get there.