is done because the gutter itself must be hung level and true to form the cornice. When such inner-linings are used they are formed of not less than 16-ounce copper to fit the contour of the gutter and are set in place and soldered to the sides to provide a sloping floor to the outlet. Where possible, such construction is to be avoided as it is expensive both from a material and labor standpoint. It will generally be found more economical to design the gutters with enough outlets to make inner-linings unnecessary.

SIZES OF SEAMS

   The development of a standing seam is shown in Fig. 72. To form a standing seam the sheets of copper are prepared by turning the edges of the sheets at right angles, 1¼ inches on one edge and 1½ inches on the other edge. Then (1), two sheets are placed together on the roof with the l¼-inch face of one against the 1½-inch face of the other. (2) The projecting ¼ inch of the 1½-inch face is turned completely back (180°) on the 1¼-inch face of the other. (3) The two sheets thus joined are then turned again 90° and, (4) then again 90°, and the folds pressed tightly together. The seam thus formed finishes 1 inch high. A ¾-inch finished standing seam is made by turning the edges 1, and 1¼, inches.

Fig. 72. The Standing Seam

   A double-lock flat seam or copper-lock is shown in Fig. 73. To avoid confusion the cleats necessary to hold the seams to the roofing are omitted. The steps in forming this seam are as follows: (1) Bend the edges of the sheets at right angles, one edge 1¼ inches, the other 1½ inches. (2) Place the sheets together, a l¼-inch edge against a 1½-inch edge. (3) Turn the l½-inch edge 180° down on the 1¼-inch edge. (4) Turn both together again, in the same direction, another 180° and then, (5) turn both in the same direction 90° down on the roof sheet, mallet together and, on flat roof work, tip the outer edge with solder.

Fig. 73. A Double or Copper-lock Seam

The method of securing copper sheets by cleats and a single-lock flat seam is shown in Fig. 74.

Fig. 74. A Single-lock Flat Seam and Cleat

   The steps in the process are as follows: (1) Tin the edges of the sheet. (2) Bend the edges of the sheets at right angles. (3) Place the sheet with the short bend on the roof. (4) Place the cleat against the sheet and nail the cleat to the roof and turn the end back over the nails. (5) Place the second sheet in position and, (6) turn the edge of the second sheet and the cleat 180° down over the edge of first sheet. Then, (7) turn all together 90° in the same direction down on the first sheet, flatten and solder.

   Fig. 75 illustrates the lap seam. The edges of the sheets are tinned 1½ inches, placed in position, and soldered. Lap seams are often made less than 1 inch wide, and in places where there is little or no strain on the seam, a ½-inch lap may well prove sufficient. All lap seams on flashings where there is any likelihood of strain should not be less than 1 inch.

Fig. 75. A Lap Seam

- 49 -