What to consider when specifying and installing the most durable of flashings.
Considered the "Cadillac" of flashing materials, stainless steel and cooper match the durability and longevity masonry provides. Both types of metal flashing are often specified for masonry buildings designed to last 50 to 100 years or more, and offer several advantages over other flashing materials: Durability; UV-resistance; Installation at any temperature; Compatibility with sealant and caulks; Corrosion resistance.
Stainless steel is a hard, durable material. Used as a flashing material in masonry buildings, stainless steel should meet the requirements of ASTM A 167 "Specification for Stainless and Heat-Resisting Chromium-Nickel Steel Plate, Sheet, and Strip, Type 304."
Most architects specify stainless steel flashing to be "dead-soft", indicating a more malleable composition.
Stainless steel is generally more reflective than copper. Today, stainless steel flashing is usually lower in cost than copper flashing of equivalent weight. Prices quoted range from $2.50 to $3.35 per linear foot for 12-inch-wide Type 304, 26-guage stainless steel with two bends and a drip.
Copper for use in masonry should conform to ASTM B 370 "Specification for Copper Sheet and Strip for Building Construction, soft-tempered." Lead-coated copper should meet the requirements in ASTM B 101 "Specification for Lead-Coated Copper Sheet and Strip for Building Construction."
The primary advantage of copper is that it is more flexible than stainless steel, while still being very durable.
Copper is often used in historic restoration to match existing materials and on new buildings designed to blend in with older surroundings.
Prices of copper quoted vary even more widely than for stainless steel. Material costs of 16-ounce cold-rolled copper ranged from $3.00 to $8.00 per linear foot for a 12-inch-wide section with two bends and a drip edge.