This traditional flashing material is durable and compatible with CA- and ACQ-treated lumber. It is expensive, however. At least two manufacturers sell flashing with a sheet of copper on one side and a sheet of polypropylene on the other. Not only is it a good bit cheaper ($45 to $68 for a 12-in. by 20-ft. roll) than straight copper, but it also can be formed by hand.
14-in. by 10-ft. roll: $110
Vinyl lasts indefinitely and won’t dent. If treated with a UV inhibitor, it also resists fading and cracking. As with other vinyl products, vinyl flashing moves with changes in temperature. To accommodate this movement, cut slotted holes for fasteners (stainless steel or hot-dipped galvanized) if they’re not already there, and nail the fasteners loosely. Vinyl flashing is generally available in white and tan.
14-in. by 30-ft. roll: $20 15⁄8-in. by 8-ft. panel: $10
Using a peel-and-stick membrane is a good idea with galvanized-steel flashing, whose zinc-covered surface degrades over time, especially in coastal environments. Frequent application of rock salt and certain other deicing chemicals on a deck also can speed up corrosion. For the best protection, choose G185 galvanized steel, which has 1.85 oz. of zinc coating per sq. ft.
14 in. by 25 ft. roll: $19 15⁄8-in. by 8-ft. panel: $20
Stainless steel is Guertin’s favorite material for flashing deck ledgers. In his coastal New England environment, stainless steel holds up very well on homes near salt water. It does the same on decks that receive salt during the winter to melt ice.
15⁄8-in. by 8-ft. panel: $30
Aluminum was the most common flashing material until CA and ACQ replaced CCA for treating lumber. Both chemicals contain more copper than CCA, which means that they corrode aluminum flashing. Separating the aluminum from the lumber with a peel-and-stick membrane is one way around this problem, but it adds a step to the installation process, not to mention an additional cost. Still, aluminum is inexpensive and readily available, so for some builders, particularly those in regions that receive little rainfall, this extra step may be worth it.
14-in. by 10-ft. roll: $6.50 15⁄8-in. by 8-ft. panel (painted): $21