ISO Board Lightweight Foam Teardrop

[TomsTwin]

Hi, a while ago I posted some renderings of an expandable teardrop design. I was going to use FRP (fiberglass reinforced paneling) with foam insulatio sandwiched between. As exra support, I was going to put wood edging. However, FRP is NOT light. That plus the wood (1/8") would still have been heavier than I wanted.

Here is my original design...


Recently we had our roof redone at work. I saw them laying down thick foam sheets for the floor. Each side of the sheet was layered with a strong fibrous paper. I asked and discovered it was ISO Board, a high density foam that you can walk on without leaving marks.

http://www.solartex.com.au/view_article.asp?id=26&cat=12

I purchased some from the local building supply store. I also contacted Raka and spoke with Larry. I told him my plan and gave him info on the product. He sent me some epoxy

Today I ran my first test. I took a 2' cut of ISO and tore the paper off of half of it. I applied the epoxy, some with fiberglass.

The results were interesting. The area where the paper was removed was poorly effeceted by the heat of the curing epoxy. It became bumpy and not flat.

HOWEVER... The areas where the paper remained, whether with or without glass matt, looked great. The paper soaked up enough of the epoxy, allowing it to bite into the foam underneath.

Based on this, I have redisigned my camper and will attempt a build with just the Epoxied ISO board. I plan on using it for the roof and walls as well as the floor. I will post my new designs soon.

Thanks for all your help... Tommy[/url]

[Miriam C.]

Well this sounds interesting. Do you have weight comparisons with the ISO and plywood? Generally walking on a tear isn't the big stressor but we get 70mph winds here all the time and they are building with it here....... Don't forget the

[TomsTwin]

Hi Miriam,

I don't have actual weight figures, but I can tell you that a 2" thick 4'x8' board can be EASILY picked up with 2 fingers.

I will pick up more boards, and start my build. Because I plan on having the roof raise and place panels in to make up the remainder of the room heaight, I will be embedding 1" Alum tubes in the side walls to act as tracks for the roof. I am using a Carry-On trailer with a rim all around. I will be bolting these tubes through the wall to the rim of the trailer for extral support.

Tommy

[b.bodemer]

Wow......this will be cool to watch you build your teardrop. Keep us posted with pics!
Barb

[aggie79]

The link was to an Australian web site. Is there a US distributor?

[TomsTwin]

Hi, here is a link to an American site. The picture looks exactly what I purchased.

http://www.polyiso.org/ContentPage/ContentPage5,45.html

They call it PolyISO.

My next experiment will be joining the walls at the corners. I will probably cut channelt out to interlock them and glue them with something like Gorilla glue or a construction adhesive. As I mentioned before, applying epoxy on the bare foam causes it to become "bumpy". There isn't any paper around the edges.

To coat the walls and roof, I will leave the paper on since it soaks up the epoxy nicely. Then glass over to of the paper.

I will post more after I purchase more board and start cutting.

Tommy

[kennyrayandersen]

However, FRP is NOT light. That plus the wood (1/8") would still have been heavier than I wanted.

The only reason it would be heavy is if they used a lot of plies in the facesheets, otherwise, it should be quite light. For most of the cabin I think one ply of fiberglass will be sufficient. I will institute a small test program before finally determining the ‘allowable’ but much of the body has little load on it.

The results were interesting. The area where the paper was removed was poorly affected by the heat of the curing epoxy. It became bumpy and not flat.

That is really strange as this is a VERY common technique used in building foam airplane wings. Did you leave a lot of it together in a cup, or did you spread it out quickly to keep the heat down? I’m not sure why it would have done that as the melting temperature for polystyrene is 460 deg F – that’s pretty hot! Was the foam completely bare, or was there some type of adhesive left from the paper being glued to the foam? Could it have been the adhesive that was bumpy?

HOWEVER... The areas where the paper remained, whether with or without glass matt, looked great. The paper soaked up enough of the epoxy, allowing it to bite into the foam underneath.

What joins the paper to the foam, and that is the matrix that binds the paper together? I don’t know, but I wonder about the compatibility of the epoxy and whatever binds the paper together (unless it’s epoxy…).

Based on this, I have redisigned my camper and will attempt a build with just the Epoxied ISO board. I plan on using it for the roof and walls as well as the floor. I will post my new designs soon.

How do you plan on making the panels curved, or are you going to use only flat panels in the construction? Post away and let’s have a look, I for one, and really interested.

[TomsTwin]

Hi Kenny,

Good thought about the binder used to keep the paper on the foam being left on the foam. Perhaps that caused the strange surface. And, it may have had to do with the rough surface that remained after removing the paper. It doesn't come off easily and leaves a lot of ditches inthe foam surface where epoxy pools.

Either way, I was very happy that leaving the paper on worked as well as it did.

As for the curved areas, I am wondering if I got the thinnest sheet avaiable, how much bed I can getout of it. Another thought would be to cut it into smaller sections with beveled edges to forma curve. OR, use another material altogether that bends easily an nd just use the foam underneath between spars.

Tommy

[kennyrayandersen]

Hi Kenny,
Either way, I was very happy that leaving the paper on worked as well as it did.

AS long as you test a little beam of it and it doesn’t cause a delamination or failure at the bond line between the skin and the core, you should be good to go.

As for the curved areas, I am wondering if I got the thinnest sheet available, how much bed I can get out of it.

It’s not exactly zero, but let’s just say we could use it for approximating zero! This is one REAL challenge when working with composite panels. I’ve thought about this one LONG and HARD – I nearly hurt myself! Anyway, when people do this for real they make tooling and either machine the core or hot form it (in the case of honeycomb) to contour using tooling. You could cut the foam using patterns and a hot wire, like they do for airplane wings. Or you could set up a bit of tooling and machine it with a router (I’ve done that with wood in the past – not so hard).

The thing I finally decided was to lay up the inner ply (roof, front) with fiberglass and bond the foam to the inner ply (you could co-cure). I’m thinking of slicing the outside of the core in the inboard outboard direction every inch or couple of inches to just short of the inner skin and then wrapping it around the tear (the inside facesheet and foam would be machined away and used as a form to bend the outer panel around). All of the slits in the core would allow it to be very easily formed and then subsequently glued in place. Now, I’d epoxy the outside of the core and wrap a 1/8 inch thick plywood over the outside. This way, you wouldn’t even need to fill the slits in the foam. The inner and outer corners would be ‘stitched and glued’ to complete the assembly. (you could also do this with just plywood and no fiberglass).

Another thought would be to cut it into smaller sections with beveled edges to form a curve. OR, use another material altogether that bends easily and just use the foam underneath between spars.

This is also a viable option, but anyway the panel is not going to bend without the facesheet exhibiting a stability failure (it will experience local buckling).

[Chip]

ISO insulation is a common material used in commercial roofing applications,,, it typically comes in 1 to 4 inch thickness and has a cured high R-value,,,,(4" r-25) one thing to be careful of is the irritation factor of the fiberglass reinforcements facers,, and also get a copy of a Material Safety Data Sheet (MSDS),,, there is some irritation of breathing dust and or vapors,,, however fully enclosed in fiberglass epoxy may well eliminate this,,, any one of many commercial roofing supply companies will have access to or stock these materials,,, and a better price than Lowes,, R-Max, Hunter, Manville,AC Foam are but a few manufacturers,,,

Lemme know where ya want the first truck load delivered,,,

chipper

[kennyrayandersen]

ISO insulation is a common material used in commercial roofing applications,,, it typically comes in 1 to 4 inch thickness and has a cured high R-value,,,,(4" r-25) one thing to be careful of is the irritation factor of the fiberglass reinforcements facers,, and also get a copy of a Material Safety Data Sheet (MSDS),,, there is some irritation of breathing dust and or vapors,,, however fully enclosed in fiberglass epoxy may well eliminate this,,, any one of many commercial roofing supply companies will have access to or stock these materials,,, and a better price than Lowes,, R-Max, Hunter, Manville,AC Foam are but a few manufacturers,,,

Lemme know where ya want the first truck load delivered,,,

chipper

Wouldn’t this just pretty much be the 2 lb/cu ft EPS foam similar to what home depot sells (sans the paper facing?). I’m thinking 2 inches for the floor and 1 inch for the walls. You know after thinking about that previous post I made and thinking about what was said earlier, I think for the curved part you could use the one inch material and just strip of the paper facesheet, score the sheet across, bend it like I was saying and then cover with 1/8 ply wood. Again, this is so you could avoid filling all if the slits, which will spread open as you bend the sheet around the tear.

[Chip]

EPS is more short form for us roofers,,,, Expanded or Extruded polystyrene,,,, kinda sorta same as Isocyanurate (Iso) but completely different materials and the paper facers dont have all the fiberglass fibers in them that Iso has,,, there is less fuming problems wid EPS but it does poorley with most epoxy's plus it melts around 185 to `195 degrees f ,,, also eps will smolder and give off nasty fumes if a fire were to start around it,,, iso is more heat resistant,, we can mop 500 degree f asphalt directly to the facer sheets without much if any damage,,, Both insulations can be used to an advantage but just be aware of where ya are using it and what each would be exposed to,,, Eps is cheaper per bd foot than iso but R valus to R value there is less difference in cost,,, expanded (styrofoam cooler) has a 4.17 r value,, while extruded,,(blue board) had an r of 5 per inch and iso is up around 7.25 per inch,,,

hope this info will help and not scare ya off,,, just be aware of each of the insulations properties

chipper

[kennyrayandersen]

EPS is more short form for us roofers,,,, Expanded or Extruded polystyrene,,,, kinda sorta same as Isocyanurate (Iso) but completely different materials and the paper facers dont have all the fiberglass fibers in them that Iso has,,, there is less fuming problems wid EPS but it does poorley with most epoxy's plus it melts around 185 to `195 degrees f ,,, also eps will smolder and give off nasty fumes if a fire were to start around it,,, iso is more heat resistant,, we can mop 500 degree f asphalt directly to the facer sheets without much if any damage,,, Both insulations can be used to an advantage but just be aware of where ya are using it and what each would be exposed to,,, Eps is cheaper per bd foot than iso but R valus to R value there is less difference in cost,,, expanded (styrofoam cooler) has a 4.17 r value,, while extruded,,(blue board) had an r of 5 per inch and iso is up around 7.25 per inch,,,

hope this info will help and not scare ya off,,, just be aware of each of the insulations properties

chipper

So you’re saying that the blue HD extruded foam melts at 195 F? I can only find the 240deg C number for the melting temperature of EPS. I found this on a building materials site:

Polystyrene's most common use is as expanded polystyrene (EPS). Expanded polystyrene is produced from a mixture of about 90-95% polystyrene and 5-10% gaseous blowing agent, most commonly pentane or carbon dioxide[4]. The solid plastic is expanded into a foam through the use of heat, usually steam.

Extruded polystyrene (XPS), which is different from expanded polystyrene (EPS), is commonly known by the trade name Styrofoam. The voids filled with trapped air give it low thermal conductivity. This makes it ideal as a construction material and it is therefore sometimes used in structural insulated panel building systems. It is also used as insulation in building structures, as molded packing material for cushioning fragile equipment inside boxes, as packing "peanuts", as non-weight-bearing architectural structures (such as pillars), and also in crafts and model building, particularly architectural models. Foamed between two sheets of paper, it makes a more-uniform substitute for corrugated cardboard, tradenamed Fome-Cor. A more unexpected use for the material is as a lightweight fill for embankments in the civil engineering industry [5].

Expanded polystyrene used to contain CFCs, but other, more environmentally-safe blowing agents are now used. Because it is an aromatic hydrocarbon, it burns with an orange-yellow flame, giving off soot, as opposed to non-aromatic hydrocarbon polymers such as polyethylene, which burn with a light yellow flame (often with a blue tinge) and no soot.

Are you referring to the beaded stuff, as opposed to the rigid blue or pink stuff? I know that the blue/pink stuff is used in homebuilt airplanes and that temperatures sitting on the tarmac can reach 180 deg F, so it would seem to be a problem if the melting temperature were as low as 195 F, no?

Also, it would seem extraordinarily handy if you could get it in 5 foot widths, which I think I can get the EPS in (BTW, it is used for building insulation) in blocks 5’x5’x10’ and you can have it sliced in the thicknesses that you want, I believe (I’m hoping to be able to buy part of a block 5 foot wide so I don’t have to splice). Do you think that this stuff is the ISO material that you are talking about?

[Chip]

Maybe I wasnt tatally clear,, EPS (expanded) has a low melt temp, while EPS (extruded) has a slightly higher melt point and yes around 240 f is a good approximation,,,, Iso has a very high melt point,,, Now to clarify,, "melt" point,, is not where it shrivles up into a pool of jelled mass but the point it starts to deform and melt,, all three insulations work well in particular cases but each is completely different,,,

EPS(expanded) is manufactured in blocks called pigs,,, I am not sure of the size but 4 or 5 foot x 4 or 5 x 30 foot is about right,, this is not ISO,,, 4" is about max thickness for manufacturing,, but if ya get in touch with an EPS expander they can cut the blocks into any shape you want with a hot wire cutter,, most have their cutters set up on a computerized cnc type set up,, also,, density of the bead board is important as to how hard it is,,, 1# nominal density is basic stuff,, real soft ans breaks apart easy,,, The 2# and up density is fairly hard and stable ,,, good stuff to work with

chipper

[kennyrayandersen]

Thanks for the info!