Here is my tutorial for installing insulation in an enclosed cargo trailer.

I installed a Coleman Polar Cub 9200 BTU rooftop air conditioner last year in my trailer, I was hoping for a cool place to relax during some of the hot days at the air field, but during the Jet World Masters event in Dayton the weather was 95 degrees almost everyday for two weeks and the air conditioner did not cool the trailer. I think it was cooler outside than in the trailer. I touched the ceiling of my trailer and it was so hot during the day I could not leave my hand on the bare metal for more than a second.

I decided that I needed to insulate the ceiling of the trailer. I looked around at the events and not many people have rooftop air conditioners and I could not find anyone who insulated their own trailer ceilings. I talked to several people about what type of insulation should I use and what would be the best/ easiest/cheapest way to insulate the ceiling. We came up with Styrofoam board, bubble wrap and spray foam insulation. I called United Cargo, I am following their recommendation.

1 Remove the lights, air conditioner and other things from the ceiling.
2 Prime and paint the 1/8” luan sheeting and 1x3 boards.
3 Cut 1x3 boards to length and mount to the black steel ribs with #10 1-7/16” self tapping screws. These will be used to screw the luan plywood to.
4 Cut 3 ½” thick by 24” wide insulation to length to cover ceiling and about 6” down to the walls.
5 Spray one ceiling bay at a time with 3M #08088 General Trim Adhesive.
6 Press each precut block of insulation in there respective bay.
7 Cut luan to size, I started in the back with full pieces 32” wide with the seam down the center of the trailer and the front seam landing in the center of a 1 x 3 board.
8 After the plywood was installed, I removed two sections at a time and painted them with a final coat of high gloss paint, reinstalled them and then repeated the process with the other set of plywood.
9 I have a little cleanup work to finish, but I am happy with the look of the ceiling. Hopefully this will allow the air conditioner to cool the trailer to a milder temperature.