Solder and Sealants: Copper Gutter construction methods have traditionally relied on solder to ensure water tightness and to strengthen joints and seams.The solder used is common 50 50 tin-lead bar solder for uncoated copper, and 60-40 tin-lead for lead-coated copper. It is typically applied to mechanically fastened or formed, rigid joints. Soldered seams and joints are permanent; they should last the life of the copper. Continuous, long runs of soldered seams should be avoided to limit stress fractures.
In the weathering process, the lead contained in solder turns gray. Exposed solder in the finished joints can be minimized with the use of blind soldering. In this technique, solder is applied to the back or concealed edge of copper surfaces.
Design Area of Pitched Roofs for Copper Gutters: The roof area to be drained is a key factor in designing copper gutters and copper downspouts. The area of roof contributing runoff to each copper gutter and copper downspout should be determined. The maximum accumulation of rainfall occurs when it falls perpendicular to the roof plane. With flat roofs, it is a simple matter of calculating area, since the true roof area is equal to plan area.
When a roof is pitched, its plan area is less than its true area. However, using the true area in the calculations has typically resulted in oversized copper gutters, copper downspouts and drains. Table 4.4.1 shows the factors that should be used to determine the design area for pitched roofs. The plan roof area should be multiplied by this factor. The result is the design roof area that is