[VAC] Re: Insulation

[Dan Weeks <theprofileco@xxxxxxx>]

I'd replace the fiberglass with something else, and the fg isn't a very good
insulator, and is great mouse food, as you've discovered.

The most efficient insulation per inch available is polyisocyanurate--I've
no doubt spelled this wrong--it's sold under the brand name Celotex at most
home stores in sheets of varying thickness, with a foil facing to reflect
radiant heat. an inch is equal to about r-11, as I remember, with the foil
adding even more to the value. Problem is, this stuff won't completely fill
the wall cavity, allowing for air movement in there, which will negate some
of the value of the insulation.

Better solution would be to spray foam insulation in there, or have it done,
completely filling the wall cavity. Even that, though, wouldn't solve the
biggest insulation problems with airstreams--namely, that the inner skins
collect heat, transfer it through the aluminum ribs to the outer skins,
which radiate it out to the atmosphere very effectively. This is called
thermal bridging, and allows much of the heat to get around the insulation.

Best solution would be to fur out the original ribs with some material that
has some insulation value to create additional space between the inner and
outer skins, and to create a thermal break between the aluminum ribs and the
inner skin, then spray foam into that cavity, then cut down the inner skin
panels and reattach them. You'd loose some interior space, but gain huge
insulation benefits. For more on this technique, see www.healthy-homes.com.
They retrofit old airstreams this way for cold-climate habitation.

A far cheaper, easier, and less invasive is to buy Reflectix brand
insulation--the type described below--also at home center stores. Relatively
cheap, flexible, comes in rolls. I think I am the fellow the writer below
was refering to--I've found this stuff easy to install on the interior
surface of the inner skins using fiberglass double-sided carpet tape. The
stuff creates a barrier for radiant heat loss, and a thermal break with the
aluminum skin-rib-skin route for heat out. I've so far only applied this
stuff inside the closets of my rig, but it does make quite a difference. Of
course, it makes the interior look like a space station . . .

Dan Weeks
75 Argosy 26
Des Moines