rib insulation

[vet57air]

Getting to insulating the walls which is a topic in its self. What i am concerned with is insulating the ribs. I have seen trailers that have had water condensating only along the ribs. I am assuming that this because the outside being aluminum being in contact with an aluminum rib transfers cold well (heat not so much a problem) and if the inside skin is placed directly over the rib condensation can occur at that point. Has anyone had this problem? Is there a good cure?

[Wabbiteer]

One point to consider is if this AS will be a stationary trailer - or will see 1000's of miles of travel, secondary roads, gravel roads etc..

A concern with anything not metal on the ribs is* how to achieve the proper anchor for interior skin to work in concert with the true riveted exterior skin to make the eggshell monoque structure as immobile as possible.

The shear strength of a pop rivet succesfully installed and compressing two of more sheets of metal together gets multiplied by 12, 24, 36 other rivets on the same full length sheet of interior liner.

Allow a low density material insert a gap inbetween each of those riveted metal surfaces and under travel vibrations the pop rivets will rapidly loose their bite and accumulate movement; along with 'black rings' showing on the interior liners from aluminum dust and allow shell flex that will get transmitted to odd places away from the loose rivets.

anyhow - assembling panels by hand without using jigs and full rib curve clamps increases the likelihood on building slack in even without adding any thermal break.

Protecting the pinch point surrounding each rivet by inserting a large metal washer or rectangular shim; and increasing the number of fasteners might eliminate the weaknesses inserted by adding a thermal break.

Note, I have bulk high density silicone sheet waiting to cut strips out of, and rolls of the gnarliest 3M 'tar' adhesive I could find.. . And am still undecided how to best install a thermal break!!

[rangebowdrie]

I'am also thinking that certain materials, between the skin, and ribs, might lead to lose rivits. I wonder if something as simple as a layer, or two of the tape that they use to wrap gas pipes migh not serve as a fairly good barrior,,,,?
Just something to reduce the direct metal contact.

[dwightdi]

If the only problem you are worried about is condensation at the places the ribs are, you can simply reduce the relative humidity inside the trailer by increasing the air flow through the trailer. By bringing in more outside cold air and heating it with the furnace you reduce the relative humidity. The RH drops by a factor of two for each 15 degrees temperature difference between the outside temperature and the exit temperature of the furnace. Newer Airstreams incorporate a foam tape (double back adhesive) over the ribs (on the outside) which both tries to improve the insulation of the trailer and reduce the number of rivets required to transmit the stresses between the outer skin and the ribs. You could likely find out what brand and grade they use by calling Jackson Center.