Teardrops n Tiny Travel Trailers

I finally sold my golf cart and when the buyer came to pick it up, upon seeing the mess in my garage he asked about my project.

After explaining briefly about the foam building process and how I was trying to collect as much of the building materials from the free section of craigslist. He said "Oh that's pretty cool" but didn't seem very impressed.

So we load the golf cart in his truck and we're saying our thank-you's and nice to meet you's. Then just as he's getting ready to leave, he pulls his business card out, hands it to me and says "I'm the General Contractor on a project not too far from here and I've got some left over material I think you could use. Give me a call tomorrow and you can come take a look at it."

Next day I went and took a look and came home with this:





I got 2 full 4 x 8 sheets, 2~ 4 x4 pieces, 4 pieces roughly 2 x 8, It's 4 inch foam bonded to 1/2 inch plywood.
He also gave me 70 feet of thick metal "L" flashing that is 4inches tall. It's the real shiny metal in the 2nd pic.

What a score!!!! That looks like the good stuff.

That’s not the brown crumbly polyurethane foam eh ???

It's the same as the blue and pink foam. It's actually an off white color but looks yellow in the pic.

He told me it was used as an under layment for a flat section of the roof. It's 4" thick foam that is sandwiched between what looks like asphalt roofing paper only a lot thinner than normal roofing paper. Then that is bonded on one side with 1/2" plywood.

Whatever they used for glue has the best adhesion of anything I've seen. I tried tearing the paper off the foam and it's almost impossible to get it off. The bond on the plywood side is just as strong.

The foam itself behaves just like the xps foam. Real easy to cut, real fine "foamdust" instead of the little round "bb's" that you get from eps foam.

Best thing about it was the price!

I think that it is a so called "polyiso" foam. I did some testing with such material sometime ago, see the topic here: http://www.tnttt.com/viewtopic.php?f=55&t=61457
It is structurally similar to XPS at 20psi strength, except it is not completely a closed cell as XPS and chemically it is different.
This is what is used in refrigerator walls and roof insulation these days, it has better R-value than XPS.

You could try to hot wire the foam to test it out. If this is polyiso foam, it will not cut or melt like XPS or EPS, it will first go charcoal. Keep away from fumes. I would also be carefull with saw dust. One of similar material MSDS: https://www.carlislesyntec.com/view.aspx?mode=media&contentID=5142
As long as there is strong structural skin on top of it positively attached, the structure would work.

Splicing the foam for thinner thickness is possible with cold tools. I did not try to cut this particular kind, but I did do some cold cutting of other foam to a needed thickness so I am not new to the "idea". I would probably try to use an old (thinest) band saw blade if that could be tensioned straight or even a slightly roughened steel string tensioned straight above flat surface and then the foam could be moved in a small sawing motion on the surface to make splicing cuts. Just my 2 cents.