Polyethylene films rank high among the relatively new materials which have helped the field of construction. A case in point is the recent use of a polyethylene hood the size of a football field to cover an entire concrete construction project. Designers of the building had specified lift-slab concrete construction. To place 4,500 cubic yards of concrete in eight weeks meant full protection every day. But Georgia's coldest winter in history threatened to shoot holes in the tight schedule. Accordingly, it was decided to cover the entire project with 6 mil polyethylene. It took 40,000 square feet of the plastic. After the first 50 foot steel columns had been positioned, a peaked framework was constructed of 2 by 12 inch rafters and 2 and 6 inch purlins, with 1 by 4 inch ribs to support the plastic. Stretched over the framework, the plastic was held with 1 by 2 inch ribs nailed to the lower 1 by 4 inch pieces. Allowing more than a dozen doorways in one side of the plastic cover gave the concrete crews easy access to work areas.