The quality of concrete cast in winter, when suitable protection is afforded, can be good or better than that cast in other seasons. Winter concrete construction techniques are aimed at several objectives. (1) Providing temperatures high enough to harden concrete. (2) Maintaining these temperatures to prevent concrete from freezing. (3) Obtaining the strength required for construction loads. (4) Improving worker's comfort and efficiency. (5) Protecting materials. These techniques cost money in added labor and materials; the question is, do the benefits justify the added expense? To make this decision we must first determine what the added expense will be. Let's examine some aspects of enclosure construction costs. Materials for enclosure must be inexpensive and relatively durable to permit reuse. They must seal the opening against the entry of cold air. They must be easy to erect and light in weight. Translucent material is preferable because it permits sunlight to help heat the enclosure and makes supplementary lighting unnecessary for the most part. Sizes, amounts of material involved, as well as labor will affect the cost of enclosures. Unfinished 1 by 2 inch lumber at a cost of about 2.5 cents per lineal foot can be used to fabricate these elements. Reinforced polyethylene will cost about 6 to 7 cents per square foot. The costs of materials discussed above do not reflect all costs of enclosed construction. Other costs are incurred in erecting the enclosure and dismantling, packaging, and storing the enclosure materials. Furthermore, if reuse of the enclosure materials is possible, the cost of materials and fabrications charged to the original job should be modified. The added costs of cold weather construction, as indicated by the cost of enclosures, are moderate. When these are compared with the advantages possible through continuous winter operation, they appear even more reasonable. Such extra advantages include the opportunity for the contractor to retain skilled workmen while engaging them in profitable activity.