Fig. 117 shows a portion of a roof covered in this manner. The sheets run lengthways down the slope of the roof, their side edges being turned up against the rolls, which are placed 2 feet 10½ inches apart from centre to centre.
A section of one of these rolls, showing the method of securing the zinc, is shown on a larger scale in Fig. 118.
The scored portion of the section shows one of the zinc clips, which are strips about 2 inches wide, fixed about 3 feet apart along the roll. Being doubled over the upturned side edges of the sheets, the clips hold them down, without preventing their expansion and contraction under changes of temperature.
After the sheets are laid and secured by the clips, the rolls are covered by the cap C,also formed of sheet zinc, doubled down as shown. In very exposed situations these clips may be continued so as to turn up again over the sides of the cap C, and be secured at the top.
The cap is secured by "fork connections." These consist of pointed pieces of zinc 2 or 3 inches long by about an inch wide, one end of which is soldered to the inner surface of the cap on each side, the point being free. As the cap slides on to the roll, the points of these forks ship in under the hooked portion of the clip. They thus prevent the clip from flying off, without impeding its expansion and contraction in direction of its length.
The extreme ends of the roll caps may be covered with a piece soldered on, as shown at 0 and P; but this plan has been improved upon by merely spreading out the roll cap itself at 0, forming what is called a saddle-piece, and dressing it up against the side of the ridge ; and at the end, P, by turning the end of the cap over the end of the roll, and doubling the corners of the sides of the cap under the end - thus, in both cases, doing away with soldered joints, and allowing perfect play under expansion and contraction. There are other patented methods of effecting the same object, which cannot here be described.