(Illustrated on Plate 2)

   The spacing of the seams is a matter of design and architectural effect.

   The width of the sheets is determined by the spacing of the seams. An allowance for seams must be made of 2¾ inches. Accordingly a sheet 24 inches wide would give a seam spacing of 21¼ inches. Copper sheets are stocked in widths in multiples of 2 inches and the seam spacing should be worked to these dimensions.

   Vertical bends are made on the lengthwise edges of the sheets — on one side 1½ inch and on the other 1¼ inch, the 1½-inch vertical bend on one sheet always adjoining the 1¼-inch bend on the adjacent sheet. Copper cleats, attached to the sheathing beneath the edge having a 1½-inch bend, engage the verticals, which are turned down and locked together as in Fig. 3. The seam so formed is again turned over, forming a double lock.

   If a ¾-inch finished seam is desired, the edges are bent up 1 and 1¼ inches, respectively.

   The crosswise edges are well tinned, locked, and sweated full of solder.

   On steep slopes (15 degrees or more) the tinning and soldering of the cross seams may be omitted.

   The standing seam allows lateral expansion and contraction in the space between the two vertical sections above the plane of the roof and below the lock. It should not be used on flat roofs, for, being unsoldered, it is not water-tight.

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