2 of my enclosed came with just a bare, square tubing frame on the inside. I just bought some insulating panels from Home Depot, or Lowes and cut pieces to fit in the frame. Then I covered the inside with some thin plywood, masonite board, or aluminum panels. I put an extra 12" strip of 3/4 plywood along the bottom of the walls, where a mower might bounce around on it. One trailer, I order with the insulation and interior laun walls and aluminum ceiling. It was about the samw money to let the factory do the work, unless your labor is worth less than the $10 an hour that the factory workers are paid.