Expansion joint

As the sun heats up a copper liner, every 20-foot run has the potential to expand approximately 1/4 inch, moving from the fixed end point toward the center. Without an expansion joint on a gutter this long, the solder joints would likely fail. Where expansion joints should be located depends on the gutter’s width and the thickness and profile of the copper. As a general rule of thumb, there should be an expansion joint no less than every 30 feet. Following guidelines from an old edition of Revere Products’ Copper and Common Sense, I determined that our new gutter—built with 16-ounce copper, a 5 1/4-inch bottom dimension, and sidewalls angled at 73°—should have expansion joints somewhere between 19 and 21 feet on-center, which works out to be dead-center in our 39-foot run, between the two 44-inch panels.

One end of each of these short panels overlapped the full-length panel next to it. At the other end, where the two short panels faced each other, we bent 1-inch upturned hems. We left a gap of a couple of inches between the two panels—this would become the expansion joint—then soldered vertical “dams” in the troughs. Hems at 90° on the edges of these dams would interlock with the expansion-joint cap where it crossed the gutter trough.

We installed the cap in two pieces, bending its hemmed edges over the hemmed edges in the panels, then soldering the horizontal seam between the piece running up the roof and the one covering the trough. The unsoldered hemmed edges would act as slip joints as the gutter expanded and contracted.

With the expansion joint set, we finished off the returns at each end. We used the brake and a pair of tin snips to form filler pieces that capped the ends of the trough and also covered the remaining exposed roof and the crown-molding cap returns. Where the filler met the trough, we bent a 1/2-inch leg that would form the soldered connection. To install these pieces, we slipped the legs under the liner trough, molded the upper portion to the roof, the crown-molding cap, and the gutter return, and soldered the seams.

Drop tubes

We install drop tubes last. A typical flaw with older built-in gutters is undersized drop tubes—I’ve seen them with diameters as small as 1 inch. For this gutter, we planned for larger, 3-inch-diameter drops. We began by drilling a 3-inch-diameter hole through the copper liner, plywood trough, and pine soffit. We then shaped an 8-inch-wide piece of copper over a piece of pipe and closed the tube with a single-lock seam. Next, we inserted the drop pipe through a 3-inch hole drilled into a 2×8 clamped in a vise, then pounded down the top 3/8 inch with a hammer, creating a flange that would seat itself against the trough bottom. (Copper is only so malleable—any more than a 3/8-inch flange and it will tear.) After soldering the seam, we slid the drop tube into the gutter trough—it projected about 4 inches below the pine soffit—and soldered the flange to the trough liner.

With the copper work finished, we peeled the paper from the last 12 inches of the peel-and-stick and sealed it to the copper, then nailed off the bottom three shingle courses, being careful not to drive any nails through the copper lining.

Cost

Start to finish, the work described here was mostly done with a three-man crew and took about two weeks to complete. The total cost for the gutter, including the plywood trough, was about $6,400, with the copper fabrication and installation portion accounting for about $3,100 of that (roughly $165 per linear foot). Every project has complicating factors; this one was made more difficult by the work that had to be done to compensate for the bowed, sagging wall. I expect the other gutters on the house to be a bit easier and less costly to repair when we return in the spring.