Copper and its alloys are readily joined by mechanical techniques, such as crimping, staking, riveting, and bolting; or by bonding techniques, such as soldering, brazing and welding. Selection of the best joining technique is determined by service requirements, joint configuration, thickness of components, and alloy composition.
Soldering is the preferred joining method where strong, watertight joints are required, such as for internal gutters, roofing, and flashing applications. A soldered seam joins two pieces of copper into a cohesive unit that expands and contracts as one piece. Well-soldered seams are often stronger than the original base material and provide many years of service.
Mechanical fasteners, such as screws, bolts, and rivets, are often used to strengthen the joints and seams. Continuous, long runs of soldered seams can cause stress fractures and should therefore be avoided.
Common 50-50 tin-lead bar solder is often used for uncoated copper; 60-40 tin-lead solder is used for lead-coated copper. Many lead-free solders are also acceptable.
Adhesives can be used in certain applications. Relatively thin sheet alloys can be bonded to plywood or certain types of foam which act as rigid insulation.
Brazing is the preferred method for joining pipe and tube copper alloys. Copper metal sections are joined with a non-ferrous filler material with a melting point above 800 degrees Fahrenheit but below the melting point of the base metals. Blind or concealed joints are recommended since the color match of silver filler material is fair to poor.
Welding is a process where pieces of copper are effectively melted together, either by flame, electricity, or high pressure. With increasing availability of modern TIG welding equipment, welding of even light-gauge copper decorative elements is gaining acceptance.
Instructional videos are available regarding fluxing and soldering techniques; how to make flat seam solder joints, double-lock standing seams, lap seams, soldering vertical sheet copper lap seams, and stitches (including the butterfly stitch); as well as copper tinning, bending, flaring, and brazing.