Part of the reason the roof on this 1963 Airstream Safari was collapsing under the weight of the air conditioner has to do with the Airstream design. Most of the structural aluminum ribs that arch up from the plywood floor to support the interior and exterior skins don’t span the entire width of the travel trailer. Instead of making a complete arch from one side of the trailer to the other they stop at the center of the roof. As they are also placed on alternating sides and 30″ apart on average, there isn’t a whole lot of load bearing capacity for anything besides the structure itself. The reason the ribs don’t span from side to side seems to primarily involve window and door placement. As a rib arches up from one side of the trailer there is either a window or the door in the way of that rib continuing down the other side. One of these half ribs runs on either side of the opening in the roof where the air conditioner sits. I decided the best way to spread that load out would be to continue the rib down the other side as far as possible.
Since I couldn’t run out and buy new ribs at the auto part or RV store I had to fabricate them. (I suppose I could have had a metal shop bend some aluminum C channel to the desired shape but that wasn’t really in the schedule or the budget.) I bought some off the shelf aluminum C channel that was 1.5″ wide with .5″ legs and .125″ thick. I cut it into lots of 6″ long pieces which I then riveted together in the approximate shape of the rib that I needed.
I determined that shape by forcing the roof back to it’s natural position with a couple boards wedged between the existing ribs and the plywood floor. I was then able to rivet the 6″ sections on one at a time matching the contour of the exterior skin. I also attached two pieces of 1.5″ square aluminum between the two ribs on either side of the air conditioner opening as extra reinforcement.
After everything was riveted into place I removed the 2 boards I used to wedge the ceiling in place. The structure didn’t stay exactly in the desired shape, but the sagging was very minimal and infinitely better and stronger than what existed previously. As a final test I grabbed onto the sides of the opening and pulled my feet off the ground to see how well it would support my 155 pounds. It passed the test, so I had no worries that the new 95-100 pound air conditioner would be supported adequately. Yes, that’s right I said new air conditioner. It
was hoped that the 1970’s Coleman unit would be salvageable, but after I opened it up to have a look the news wasn’t good. Rather than get everything back together and have the unit fail in a year or two it was decided to go ahead and replace it with a new one. So it was ordered and the rewiring commenced.