With flashing, as with most purchases, you get what you pay for. Deformed copper or stainless steel flashing, at more than $4 per square foot, certainly will long outlast polyvinyl chloride (PVC) flashing, averaging 10 to 25 cents per square foot. Flashing selection is a controversial topic, pitting forensic engineers and restoration specialists against designers and masonry contractors working under budget constraints. All exterior masonry walls are subjected to water penetration. Flashing materials must be impervious to moisture and resist abrasion, corrosion, and puncture. They must be able to retain an applied shape. In addition, flashing should be compatible with joint sealants, perform at elevated temperatures, and not cause masonry discoloration. The chosen flashing material should last for the life of the building, since repair costs are enormous. A wide assortment of flashing materials is available, including copper, stainless steel, PVCs and other plastics, and numerous composites, such as rubberized asphalt, copper fabric, and fiberglass-reinforced polyethylene. All have their benefits and drawbacks. Flashing materials can be divided into three general categories: sheet metals (the most expensive), flexible composites (moderately priced), and plastics (the least expensive).