Depending on your needs and your budget, there are several types of plastic film or solid material that can be used for the plastic roof and/or sides of a greenhouse. A common greenhouse film is flexible 6 mil polyethylene, an economical choice that should last between one and four years before needing replacement. It can easily be stretched over a Quonset-style tubular frame, but is more difficult to secure to a gabled structure. A second type of polyethylene has a bubble-like texture which makes it stronger and more versatile. It serves to diffuse light more efficiently, and is more durable than lightweight poly, but it is also more expensive. Other types of plastic include copolymer plastic, polyvinyl plastic or polycarbonate plastic, all available in different weights and varied textures for greenhouse coverings.
Greenhouse covering materials are available as reinforced or non-reinforced film. Although the reinforced covers are more expensive initially, they are more durable and offer better value for the money. Woven fibers are embedded in the center of two or more layers of polyethylene to add strength and prevent rips from spreading as easily. Greenhouse covers can take a beating from wind and weather, so the reinforcement is worth the extra expense. Copolymer Plastic is another upgraded covering that is more durable and lasts longer than 6 mil poly. Polyvinyl, the clear heavy plastic used frequently for the see-through windows of boat covers, is thicker than 6 mil poly and not nearly as flexible, but it is much more durable. Polycarbonate, which comes in sheets, is also a popular greenhouse covering, ideal for the do-it-yourself enthusiast or a backyard greenhouse gardener. Sheets of polycarbonate can be found at big box home supply and building outlets.
