All types of portable storage buildings have one thing in common: a polyethylene canopy. The canopy usually serves as the covering for the roof, although shed-like structures often use them for walls and doors. This type of canopy has the same composition as a polyethylene tarp and, in many cases, a replacement canopy for one of these shelters can be created by a tarp fitted to the appropriate size. Although some shelters, such as carports, may be designed with a metal roof, the polyethylene material is designed to last a long time, as well. Warranties on the canopy itself generally last up to five years and then the material can be replaced easily then.
The polyethylene used is heavy duty, as this is ideal for constant outdoor exposure. The heavy-duty polyethylene canopies are then treated to have several qualities to withstand any of the elements outside. This includes being treated to be waterproof, UV resistant, rot resistant, and mildew resistant. Some are even treated to be fire retardant, according to stringent California fire codes. Aside from these treatments, the heavy-duty nature of the fabric has a 14 by 14 denier count, which is designed to be rip-proof. These qualities not only prevent the fabric from deteriorating or ripping but also protect any of the investments inside the canopy structure.
For some structures, a simple tarp can serve as a replacement canopy, especially as individual tarps for any outdoor uses are designed in white, silver, or green. Some canopy structures, however, have a more specific design, which isn’t always met by the design of a tarp. Shed-shaped portable shelters, for example, often have a canopy with three walls and a roof shaped like a shed that fits over the traditional frame. Rounded roof canopies have the same type of concept. Dealers of portable garages and other portable buildings often carry these specific replacement canopies for outdoor shelters of various shapes.