R value difference between foam sandwich panel vs honeycomb panels.

[SamMazer]

I'm sure it's been covered but I can't find it.
I am building a ex truck and got quote on 2.36" FRP/ foam panels and 3" honeycomb panels. Nice lady that gave me the quote has no idea on R values and no engineers were available.

It's about the same price , I know the honeycomb is much stronger and what I'm leaning to, but insulating quality is VERY important for my intended use.

Any help would be appreciated.
Thanks

 

[Victorian]

r-value

Extruded Polystyrene (blue foam)(XPS) has an R Value of 5-5.4 per 1" thickness

Polyurethane (yellow foam)(PU) has an R value of 6 per 1" thickness. Compare to the XPS it will break down sooner (15-20 years) but can handle chemicals better (like polyester resin)

PP Honeycomb has an R value of ~ 2.5- 3.5 per 1" thickness

 

[IdaSHO]

r-value


Polyurethane (yellow foam)(PU) has an R value of 6 per 1" thickness. Compare to the XPS it will break down sooner (15-20 years) but can handle chemicals better (like polyester resin)

Are you referring to Polyiso?

If so, the biggest factor that lead me away from it to XPS is flammability.
Second to that is that is is an open-celled foam, and it will absorb water.


This PDF has some great info on XPS and Polyiso.

Whats interesting is the R-value performance of both as the temps drop.

The results are interesting, and provide even more reason to go XPS :ylsmoke:

http://www.owenscorning.com/NetworkShare/EIS/10019950-FOAMULAR-XPS-vs-Poly-FAQ.pdf

 

[Victorian]

That's a good read! Thank you for sharing.
I'm not sure if Polysio is the same as Polyurethane... But I don't think so. Will have to look into it.
As for flammability: I did some very basic testing with a lighter and a couple of pieces of foam. I recorded it but it's not internet worthy. I found that neither type of foam will burn on it's own. As soon as the heat source is taken away the smoking/burning stops. The XPS produced a flame durring the testing, the PU was just "crackling away". In any case, both foams will be incased between fiberglass skins anyway and they can take a lot of beating before any fire would reach the core.
As for holding water: I have worked with both foams in the RV industry and none of them will "hold" water. At least not like a piece of cloth. No matter what, just don't get it wet. If you get water inside a panel, simply drill a drain hole in the bottom edge and let it drain.

 

[SamMazer]

Exactly what I needed
Thanks

 

[NeverEnough]

Unless the honeycomb cavities are filled with foam, a foam-core panel will have far better thermal performance. That's why my build (all PPE honeycomb) included an aerogel insulation layer in the living spaces. If you're looking into PPE honeycomb, it has some great attributes for a box destined for abuse, but thermal performance is not at the top of the list. The foam-core panels have proven to be strong enough for expo vehicles. However, if you are willing put the cash out and suffer a bit of a weight penalty, you can go for Transonite panels and have both strength and thermal performance. That's some tough stuff!

 

[IdaSHO]

Interesting, thanks for posting about Transonite panels

Do you have any specific data about them, like R-value?

My google-**** is failing me

 

[david506th]

The "Adrift in the Green Room F550" build is using transonite and I believe he has said that it's hard to get ahold of

 

[NeverEnough]

Here's specs from one of the configurations:
Thickness: 3.5” (88.9mm)
Face Skin Thickness: 0.17” (4.3mm)
FIPSI: 4.0 Staggered Pattern
Weight: 5.3 psf (25.9 kg/m2)
Core Material: Polyisocyanurate Foam 2 pcf density
Thermal Resistance: 11.67 hr*ft2*°F/BTU

Last I checked, Creative Pultrusions has the manufacturing and distribution license to Transonite. It's expensive stuff to make, and so there's a minimum order involved, which makes its use for "one off" projects difficult. I got some samples about two years ago, did some testing, and was very impressed. Here's the URL for Creative's Transonite page: http://www.creativepultrusions.com/index.cfm/products-solutions/transonite-panel-system/

 

[Ozarker]

Unless the honeycomb cavities are filled with foam, a foam-core panel will have far better thermal performance. That's why my build (all PPE honeycomb) included an aerogel insulation layer in the living spaces. If you're looking into PPE honeycomb, it has some great attributes for a box destined for abuse, but thermal performance is not at the top of the list. The foam-core panels have proven to be strong enough for expo vehicles. However, if you are willing put the cash out and suffer a bit of a weight penalty, you can go for Transonite panels and have both strength and thermal performance. That's some tough stuff!

Why not try honeycomb and foam core together, glue up your own panel. ???

 

[IdaSHO]

Depends on how think you are willing to make your walls. :sombrero:

Every time you increase their thickness you add weight and loose space.

 

[S2DM]

Here's specs from one of the configurations:
Thickness: 3.5” (88.9mm)
Face Skin Thickness: 0.17” (4.3mm)
FIPSI: 4.0 Staggered Pattern
Weight: 5.3 psf (25.9 kg/m2)
Core Material: Polyisocyanurate Foam 2 pcf density
Thermal Resistance: 11.67 hr*ft2*°F/BTU

Last I checked, Creative Pultrusions has the manufacturing and distribution license to Transonite. It's expensive stuff to make, and so there's a minimum order involved, which makes its use for "one off" projects difficult. I got some samples about two years ago, did some testing, and was very impressed. Here's the URL for Creative's Transonite page: http://www.creativepultrusions.com/index.cfm/products-solutions/transonite-panel-system/

Never Enough is right, minimum order size, hard to come across. Circuitously, we managed to score some overage from another job which made it less unreasonable, but its still rather expensive. Incredibly strong stuff.

We were quoted an r of 12.5 for a 3.5" thick panel. They come in several varieties, all with different R values and different methods of pultruded crosslinking between the faces. We used a 2" panel in the floors and 1" everywhere else. The 2" panel is outrageously burly.