XPS Sandwich Panels availability in the US

[rruff]

You will obviously need some sort of framing, but yes, avoid wood in the construction where you can so you are avoiding the inevitable wood rot.

No framing is needed actually... Just foam and skins. Use angle for the edges.

Why bother with epoxy resin and fiberglass? The resin is expensive, caustic and a PITA to work with, so is fiber glass.

Polyester resin is nasty, but I thought the epoxy I used was fine. And not that expensive either... most I bought for $30/gal but it rose to $60 during covid. I think someone bought them out also.

Sanding fiberglass is nasty and messy though... one of least favorite things. I agree that gluing skins onto foam seems like the best method... but I wouldn't use XPS, rather PVC foam. XPS is quite weak.

 

[dbhost]

No framing is needed actually... Just foam and skins. Use angle for the edges.



Polyester resin is nasty, but I thought the epoxy I used was fine. And not that expensive either... most I bought for $30/gal but it rose to $60 during covid. I think someone bought them out also.

Sanding fiberglass is nasty and messy though... one of least favorite things. I agree that gluing skins onto foam seems like the best method... but I wouldn't use XPS, rather PVC foam. XPS is quite weak.

On the Epoxy instead of Polyester resin with XPS foam, Polyester resin with basicall melt XPS foam.

On the framing thing. I would have to test that... I am a big, quite fat man and I am not sure I would trust XPS / Fiberglass alone to support my fat tail in an overcab sleeper...

 

[windblown]

I just got a quote on premade sandwhich panels from corelitecomposites. 6 panels (PET core, FRP skin) to make a 6.5x11.5x6.75 box. $9300.

 

[The Artisan]

I just got a quote on premade sandwhich panels from corelitecomposites. 6 panels (PET core, FRP skin) to make a 6.5x11.5x6.75 box. $9300.

The shipping cost can get expensive unless that is shipped or you can pick them up.
Kevin

 

[rruff]

I just got a quote on premade sandwhich panels from corelitecomposites. 6 panels (PET core, FRP skin) to make a 6.5x11.5x6.75 box. $9300.

Just a rectangular box? Anyway, if it's ~400 ft^2 that comes to $23/ft^2 which isn't terrible. I think you could DIY for around half that (not XPS; structural foam), and a TC kit would be around double.

Did you inquire about any other prices? PVC, just foam, etc.

 

[rruff]

On the framing thing. I would have to test that... I am a big, quite fat man and I am not sure I would trust XPS / Fiberglass alone to support my fat tail in an overcab sleeper...

I wouldn't trust hardware store XPS without framing, either.

 

[rruff]

You might find the link interesting:

Carbon Fiber Truck Camper Build: The Titan Expedition Vehicle

Eric Davis designed and built a remarkably innovative hard side pop-up carbon fiber truck camper. Check it out!

www.truckcampermagazine.com

He used to have a thorough build site, and a thread on here as well... since deleted. I think he ended up selling the truck and camper both for $15k prior to covid... ah, the good old days when bargains could be had! As I recall he thought the bond between the skins and foam was very iffy (he built the camper out of foam first), but the carbon (!) skins were robust and thick enough that it had enough structural integrity anyway. There was no framing.

I've seen several people have bonding and foam-structural issues XPS that I'd have a hard time trusting it.

 

[dbhost]

I wouldn't trust hardware store XPS without framing, either.

Not just hardware store XPS, I am not sure I would trust pre made XPS panels without framing support.

 

[KiwiMtnClmbr]

There are more and more structural foams available; I was able to get PE marine foam for 35% less $ than the equivalent rated PVC. It's heavier, but for my needs that's worth the financial outlay at this time. PU foam isn't as desirable because of its friability, but many many builds are out there with PU composite panels getting pounded over rough terrain, especially in Oz, and they seem to be holding up well.

 

[1000arms]

You might find the link interesting:

Carbon Fiber Truck Camper Build: The Titan Expedition Vehicle

Eric Davis designed and built a remarkably innovative hard side pop-up carbon fiber truck camper. Check it out!

www.truckcampermagazine.com

He used to have a thorough build site, and a thread on here as well... since deleted. I think he ended up selling the truck and camper both for $15k prior to covid... ah, the good old days when bargains could be had! As I recall he thought the bond between the skins and foam was very iffy (he built the camper out of foam first), but the carbon (!) skins were robust and thick enough that it had enough structural integrity anyway. There was no framing.

I've seen several people have bonding and foam-structural issues XPS that I'd have a hard time trusting it.

Have you tested Loctite PL 300 VOC Foamboard Adhesive? https://www.loctiteproducts.com/en/...line/loctite_pl_300_vocfoamboardadhesive.html

I suspect that even with a good bond across the entire adhered surface, one would need to minimize stresses that would tend to peel the foam from the other material (the adhesive might hold while the foam fails).

 

[rruff]

Have you tested Loctite PL 300 VOC Foamboard Adhesive?

Pretty sure I tried that many years ago and had no luck. PLPremium was better.

The best method I came up with was to sand the XPS surface, use a wallpaper perforator to give the surface a lot of little cone-shaped indentations, work epoxy into the indentations and let cure until firm but not fully, then do the final FG layup or skin bonding. If you were to use a ply skin, you'd want to epoxy to soak into that also before bonding.

It's still weak compared to PVC, and obviously more work. Since you can get PVC foam from Carbon Core for not too much (~$6/ft^2 for 1.5"; free shipping for quantity... with a whole camper being enough for that), that seems like a better way to go. Thermal resistance is just as good also. **Note, last time I bought foam was a couple years ago, so I don't know if free shipping is still in effect. I checked prices recently and that is about the same, though.

 

[1000arms]

Pretty sure I tried that many years ago and had no luck. PLPremium was better.

The best method I came up with was to sand the XPS surface, use a wallpaper perforator to give the surface a lot of little cone-shaped indentations, work epoxy into the indentations and let cure until firm but not fully, then do the final FG layup or skin bonding. If you were to use a ply skin, you'd want to epoxy to soak into that also before bonding.

It's still weak compared to PVC, and obviously more work. Since you can get PVC foam from Carbon Core for not too much (~$6/ft^2 for 1.5"; free shipping for quantity... with a whole camper being enough for that), that seems like a better way to go. Thermal resistance is just as good also. **Note, last time I bought foam was a couple years ago, so I don't know if free shipping is still in effect. I checked prices recently and that is about the same, though.

Thank you.

 

[Louisd75]

Pretty sure I tried that many years ago and had no luck. PLPremium was better.

The best method I came up with was to sand the XPS surface, use a wallpaper perforator to give the surface a lot of little cone-shaped indentations, work epoxy into the indentations and let cure until firm but not fully, then do the final FG layup or skin bonding. If you were to use a ply skin, you'd want to epoxy to soak into that also before bonding.

It's still weak compared to PVC, and obviously more work. Since you can get PVC foam from Carbon Core for not too much (~$6/ft^2 for 1.5"; free shipping for quantity... with a whole camper being enough for that), that seems like a better way to go. Thermal resistance is just as good also. **Note, last time I bought foam was a couple years ago, so I don't know if free shipping is still in effect. I checked prices recently and that is about the same, though.

My main concern about PVC is that offgassing can cause an aluminum or fiberglass skin to delaminate over time should the temperatures get too high. Other than that, it checks a lot of boxes. I'm not sure if the offgassing issue is eliminated by avoiding a skin and laying up the fiberglass directly on the foam.

 

[KiwiMtnClmbr]

Check the marine spec structural PVC foams from Gurit, Divinycell, etc. as they're well established for use in tropical conditions. Fwiw, one of the benefits of PE over PVC is it's ability to handle very high environmental temperatures.

This gives a good picture of the pros and cons: https://www.boatdesign.net/articles/foam-core-properties/index.htm

 

[rruff]

My main concern about PVC is that offgassing can cause an aluminum or fiberglass skin to delaminate over time should the temperatures get too high. Other than that, it checks a lot of boxes. I'm not sure if the offgassing issue is eliminated by avoiding a skin and laying up the fiberglass directly on the foam.

Where did you see that? I have heard of outgassing XPS delaminating the hand-laid FG... but not PVC. I think a continuous bond with epoxy would be as good as FG layup. Temp specs for the foam are up to 185F skins when made as a sandwich panel.

Mine did sit out in the sun last summer and isn't showing signs of delaminating. I hope it doesn't since I'll be in big trouble if it does!