How to Insulate a Cargo Trailer

by John Cagney Nash

Cargo trailers, whether those used as 18-wheeler rigs or vehicles needing no special operator's license, tend to be hard-sided units skinned in aluminum sheeting and made rigid with support hoops and rails. The supports are usually approximately 1 1/4-inch deep. This structure lends itself well to the installation of insulation.

Step 1

Remove any preexisting paneling or liner from the inside of the cargo trailer. Clean the walls using a 10-to-1 dilution of dish washing detergent, then rinse with clean water.

Step 2

Create a vapor barrier to protect the finished project from condensation that can form in extreme temperatures. Proprietary vapor barriers are available in the air conditioner aisles of home improvement warehouses. An extremely efficient and cost-effective alternative is to glue sheets of bubble-wrap to the inside of the cargo trailer's skin. Some rigid insulation panels are supplied with an integral vapor barrier; if using these products this step should be ignored.

Step 3

Install batt -- sometimes called blanket -- insulation, commonly available in 18- and 24-inch widths. Apply a proprietary glue to one section of inner wall at a time. Unroll the batts on the floor and cut them to size with shears. Press them into position over the glue. Leave the bottom 2 inches without insulation to create an area into which condensation can settle, and provide drainage from this space. Batt insulation is a cost-effective option for walls, but cannot be attached to ceilings.

Step 4

Install fire-resistant rigid panels made of fiberglass or polystyrene. As soon as possible --- usually when the space between each support hoop has been filled with batt --- install the interior panels to help hold the batts in place. Panels finished on one side with a silver-colored metallic coating help to reflect external heat back out through the cargo trailer's skin. Cut the panels to the sizes dictated by the cargo trailer's support hoops and rails. Brush proprietary glue over the walls and press the panels into place. Again, leave the bottom 2 inches without insulation and provide drainage from this space.

Step 5

Panel the interior according to the trailer's predicted use requirements. If light, pre-packaged cargo is anticipated, use 8- by 4-foot sheets of luan plywood cut to size; if heavy use and palletized cargo is anticipated, use sheet steel or aluminum. Both types of paneling should be attached to the support hoops and rails using either self-tapping machine screws or blind rivets.

Step 6

Insulate the floor by installing a new layer of wooden flooring over the preexisting floor.

Step 7

Paint the outside of the trailer roof with insulating paint available from most home improvement warehouses and recreational vehicle dealerships.

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