Weight difference of foam vs plywood

[katozzi]

Hello!

We are still in the drawing/design phase of our trailer, but are stuck on the decision to build the sidewalls out of foam or plywood. We have been going back and forth about weight, ease of building materials, and so on.
Basically, this being our first new build, we want it to be easy to work with. Also, we are going to be pulling it with a little Chevy Cavalier, so we want it to be light as possible. Were just trying to weigh our options. I have worked with fiberglass before, just not on this scale.

Any suggestions?

[eaglesdare]

i voted for foam. but i am a bit partial since i have a foamie. it is easy to work with and it is light weight.
test a piece yourself, you'll be surprised. see if maybe the stores have a broken peice of something they may just give you. cover it with the glue and canvas. you will be surprised at the strength of it.

[starleen2]

I vote for plywood - as you can see by the green lantern - I came in very lightweight and got some size to boot - 1100 lbs. I could have made a few changes and still gone lighter! I don't think you're gonna get any lighter if you are going for a larger TTT.

[GPW]

I vote for a combination of both ... used wisely !!!

[eaglesdare]

I vote for a combination of both ... used wisely !!!

op is talking about just the side walls. that is why i said foam. wood around doors/windows for framing, but the wall itself could be foam.

[GPW]

Given the trend of thoughts , there seems to be a size trailer (cabin) that is reached , when the use of plywood becomes a positive stiffening force in reinforcing the structure , perhaps on the “Largerâ€

[Oldragbaggers]

If I were doing it over (or if I hadn't already spent so much money and done so much work on my walls for this build) I think I would have tried a foam wall laminated with 1/8" ply on both sides and minimal lightweight framing only around doors, perimeter and crucial attachment points. Of course the exterior would be covered with a lightweight fiberglass cloth.

[Larry C]

I understand the pursuit of light weight, I am going there with my build, but I don't really get the canvas/glue/paint thing? I like the foamie idea, it's just the covering I don't get. I doesn't seem this method is any lighter than fiberglass/epoxy, and I doubt it's less expensive.
The foam core reinforced with light weight wood (cedar) where needed and covered with fiberglass/epoxy would seem to me anyway that it would be superior in strength, water resistance, weight and cost, but what do I know?
I am curious if anyone has calculated the actual weight of canvas with glue per sq. yard? The glass with epoxy I use is a total of 6oz. per sq. yard.


Larry C

[pete42]

LarryC I too have wondered about the foam/canvas/glue/paint builds but GPW and eaglesdare have made a convert out of me.
having said that I'm holding off on how big of a trailer can be built until mike and others have completed theirs.

I do think fiberglass is the way to go but it takes a lot more skill and is less forgiving than the canvas/glue method plus way more toxic.

since katozzi will be pulling theirs with a chevy cavalier and didn't mention how big or what style they were looking to build.
If it were me doing a build using their restrictions foam/glue would be my choice.

Pete (isn't this site great?)

[katozzi]

Pete, yes I would agree. This site is great!!

We are planning on trying to use the Superleggera dimensions for our trailer, the only pain being the plans are in metric. http://www.angib.pwp.blueyonder.co.uk/t ... tear32.htm
I am about 6'3, so i am ruling out anything smaller than that might be a cramp.
Does anyone have a good weight comparison of foam vs wood(4x8 trailer size)? If the difference isn't staggering, then I may just stick with wood. But there sure is an appeal to using modern materials. Hence being so torn!!

[eaglesdare]

not sure about a woody trailer, but my foamie is approx 500lb total, with mattress. that includes the frame, which is 265lbs.

[GPW]

Plywood ... 57 lb./ cu.ft.
Foam ... 2 lb./ cu.ft. That says it all eh !!!

[aggie79]

Keep in mind the entire weight of the teardrop.

I like the idea of a foamie and may use the method on my second build. However, I believe that you may be able to have a less substantial trailer - meaning less weight - if for plywood construction as compared to a foamie.

If I were to construct another teardrop with light weight being the sole criteria, I would use minimalist framed sidewalls - profile perimeter, door surround, and any other hardpoints - and 3/4" foam between the framing with a single 1/8" plywood skin on the exterior only. The interior finish would be hull liner fabric adhered to the foam. The exterior would be a single layer of fiberglass epoxied to the plywood. I wouldn't fill the weave - just paint over the glass/epoxy.

My frame would be designed like Larry C's.

Take care,
Tom

[GPW]

That sounds like a real Good way of making one Tom !!! .... No Rules eh !!!...

[mikeschn]

I vote for plywood.

I built the foamie standie to learn about the pros and cons of foam.

And while there are a lot of benefits, I keep hitting a brick wall when it comes to finishing foam.

First of all, while you are working on it, every time you look at the foam wrong, you get a dent that needs to be filled. I know it'll be stronger once it's covered with canvas, but I'm not that far along yet.

Secondly, you probably should have a generous radius on the sharp corners. But I'm really struggling with how to get the canvas to lay flat on those radii.

Mike...