How to Insulate a Cargo Trailer

Written by john cagney nash
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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 aluminium 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.

Skill level:

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Things you need

  • Cleaning solution
  • Rinse water
  • Vapour barrier
  • Insulation material
  • Glue
  • Lining
  • Fasteners
  • Flooring
  • Insulating paint

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  1. 1

    Remove any pre-existing panelling 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.

  2. 2

    Create a vapour barrier to protect the finished project from condensation that can form in extreme temperatures. Proprietary vapour 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 vapour barrier; if using these products this step should be ignored.

  3. 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.

  4. 4

    Install fire-resistant rigid panels made of fibreglass 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-coloured 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.

  5. 5

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

  6. 6

    Insulate the floor by installing a new layer of wooden flooring over the pre-existing floor.

  7. 7

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

Tips and warnings

  • Roof vents such as those used in recreational vehicles allow heated air to escape.
  • Insulation is rated in "R-values;" the higher the R-value the greater the product's insulation capabilities.
  • Heavy carpet is also an excellent insulator for trailer flooring, but only if the cargo is unlikely to leak fluids and doesn't require forklifts to manoeuvre.
  • Neither loose-fill or expanding foam insulation is a viable option when retrofitting a cargo trailer.

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