If you purchase greenhouse grade polyethylene film (Teflon Coated on one side) the film will normally last 4 - 5 years. When putting on the film, the Teflon coated side faces the outside toward the sun. - Millet (1,121-)

This is true. I haven't gone that route yet because I haven't gone three years that I haven't changed the size of my greenhouse! When I finally settle on what size I want the permanent house I'll go with real greenhouse plastic.

My experience with plastic anything in Florida is to knock at least one year off the supposed life of the product. When the PVC pipe in my current house gives it up in another two to three years I'll probably put the permanent house in.

.....Alan.