Lets talk about rigid foam insulation

[IdaSHO]

Custom camper builds, what is being used?

Im in the final planning stages of my camper, and need to make a final decision on insulation.

So far I have is narrowed down to two options...

Extruded polystyrene, and Polyisocyanurate w/ foil face.

I like the idea of the radiant shield, and the additional R-value of the Polyisocyanurate, but it has its drawbacks.

R-value of 6.8 per inch
Foil face on both sides
brittle
Cellular reception within camper will suffer greatly
easy to seal joints (foil tape)
I have a concern of moisture condensation on the aluminum surfaces



The Extruded polystyrene is tough stuff, has a slightly less R-value, but can be difficult to seal joins 100%

R-value of 5 per inch
closed cell foam
very tough
nothing seems to stick to it, hard to tape joints.


Any comments? Suggestions?

 

[Greg]

Extruded Polystyrene (XPS polystyrene)

The expert here is Pods8. His build thread and design thread are both posted under the pop-up section.

http://www.expeditionportal.com/for...re-fiberglass-skin-pop-up-camper-build-thread
http://www.expeditionportal.com/forum/threads/54664-POD-Custom-camper-design-stage

Tribu built his Kubic camper using XPS polystyrene sandwiched between two thin layers of PVC foam then coated with polyurea coating

http://www.expeditionportal.com/forum/threads/58224-Making-my-Uro-Camper-Kubic-1-0
http://www.expeditionportal.com/forum/threads/70648-Polyurea-as-a-camper-skin?highlight=polyurea (see video in post#3)

The HUF adventure camper used XPS polystyrene
http://www.hookedupfilms.com/category/huf-adventure-vehicle/


From the boatdesign.net see post#14 by pcfithian
http://www.boatdesign.net/forums/fi...-building/extruded-polystyrene-xps-24213.html

 

[Greg]

XPS Polystyrene

Forgot that the teardrop trailer people are heavily into DIY trailers with XPS polystyrene. They call them Foamies

http://www.tnttt.com/viewforum.php?f=55

 

[AeroNautiCal]

You may find this to be useful, as the guy did some good research on insulation for his expo build.

 

[Greg]

IdaSHO,

After re-reading your question I now see you were just looking at using rigid foam for thermal insulation, not for any structural core. My thoughts have been so locked on how to use rigid foam as a structural core and how to quickly, cheaply get a skin to cover it that my answer was way off.

Anyway, good luck with your project, hopefully we'll see some photos.

Greg

 

[IdaSHO]

Thanks Greg.

You are correct, the foam will not be structural. Though once part of the complete wall system it WILL provide a good deal of additional strength.

 

[Haf-E]

The foam will only add much strength if it is attached to the structural portion - i.e. using an adhesive. I've heard that XPS is hard to get anything to stick to...

The Iso type foam is also much more fire resistant - something to consider. XPS is very flammable. I used the iso type foam on the walls of my shop for that reason.

 

[Greg]

IdaSHO,

Regarding adhesion to XPS polystyrene please take a look at the link I posted to boatdesign.net as pcfithian was very positive about using 3M's Fastbond 30 water based contact cement as it "Because it allows for an instant bond between the foam and the thin luan plywood skin." (quoted from post#27)

Also regarding adhesion to XPS polystyrene see http://www.surfersteve.com/polystyrene.htm
SurferSteve says,
"Please allow me to insist you do the following:
Use an epoxy glue joint/s (in place of a stringer/s) - one is o.k., two is better.
Finish the blank by sanding lightly with #20, leaving hundreds scratches and small pits.
Add about 5% more resin to the laminate after dragging the excess resin out of the cloth."
and also
"The extra resin will fill in all the pits and scratches left on the rough blank. I realize it is hard to scratch and tear the foam of a blank you worked so hard to perfect, but do not skip this step. The pits and scratches greatly increase the bond, and with the glue joint/s, will minimize the delamination problem to a level equal to other foams. As with all boards, but especially XPS, avoid exposing an XPS board to a car interior on a hot day with the windows rolled up."

Hope this helps.

Greg

 

[jronwood]

Good info, subscribed.

Jronwood

 

[IdaSHO]

Thank for the responses guys. Looks like Ill stick with the Extruded polystyrene foam. :ylsmoke:

 

[OutbacKamper]

Another option, that could work well for filling voids of uneven shapes and thicknesses would be 2lb spray foam. The R value is approx. 6 per inch and it forms a nearly perfect vapour and air barrier. There are special trimming tools that allow you to achieve a flat surface after it has been applied.

 

[IdaSHO]

Ive looked into it, and while they do do the job very well, they are seriously cost prohibitive.

We carry "froth-packs" at work. Even at wholesale cost they cost nearly $2 per square foot @ 1-inch thick.

XPS foam is roughly $0.40 per square foot @ 1-inch thick.

For this project at 1.5" and 2" thick walls/ceiling, that's a difference of nearly $1500. With the very slight R-value difference, thats money that I would never see a return on.

 

[Adventuro-Us]

Wheres the updates on this? Id love to know how its working out.

Adventuro-Us

 

[IdaSHO]

I have a slow thread over on Pirate.

A couple of pictures though...

Im in the process of skinning the camper. Then comes the insulation this thread was regarding. Ill be using XPS foam.


Skeleton...

And working on the 6mm marine ply skins...

 

[stomperxj]

Looks great IdaSho. Got a link to your Pirate build thread?