Foam Board or Rubber Mat For Under Camper?

covered wagon wrote:

bigfootford wrote:
Bigfoot's and Northern Lite's, NO foam!
I have the same plywood in the bed of my truck for about 12 years...
I used a 1/2" rubber pad for a few years but the camper dug into it and was stressing the bottom perimeter of the camper.... Bigfoot has a thin fiberglass bottom cover for access to the holding tanks. NL does not have that but the perimeter is where the weight is distributed and is where it is the strongest!

Jim

Nice Post..... and solid advice.:)

Sorry but I believe it incorrect to come up with blanket statement such as "No Foam" and consider it solid advice without looking into the details.

Not all foam is made the same and the foam used by myself and others (and used with success) can be well suited for this application. The concern raised in this thread was whether foam was suitable for fiberglass campers because the structural support is at the walls of the base of the camper.

In my case I used FOAMULAR® 250 Extruded Polystyrene (XPS) Rigid Foam Insulation comes with a minimum compressive strength of 25 PSI. Just looking at the outside 2" edge of foam supporting the camper walls that is 2"x96" for a total area of 192 square inches with a 25 PSI rating giving me 4800 lbs of compressive strength PER side for a total of 9600 lbs of compressive strength to hold the edges of the camper. If I was to look at the total support of the entire area under the camper using the same foam I'm looking at an area of 48"x96" for a total supported area of 4608 square inches giving me a total minimum compressive strength of 115,200 lbs.

The point here is that the RIGHT type of foam is well and capable of supporting the weight requirements we are discussing. If one just needs to raise the camper by an inch or so then a sheet or two of plywood makes sense. However, in my case I need 4" of height and that would have taken over 5 sheets of plywood and added 362lbs of weight. Of course I could have built some type of structural support frame to shave some weight but then I'm stuck guessing where to try to support the underside of the camper and where not to.

That being said, if this is a matter of warranty and the manufacturer specifically states don't use foam or it will void the warranty then by all means, abide by the manufacturers recommendation. But... if you have a camper not under warranty and need to add significant height to clear your cab then pink foam is a viable option if you use the right product.