Trough And Cap

This method is much the same as that used for copper, the difference being that the cap a is slipped over the lock b of the trough, as in Fig. 85, clips not being required to keep it in place. The fiat portions of the roof are secured with clips at the head of each sheet, made to fit into the lock seam, the clips being nailed to the roof boards.

The sides of the sheets are secured by the locking or seaming over them of the edges of the trough b. The ends of the rolls should be closed or stopped by turning down a portion of the roll cap a against the wood roll, and by folding the corners of the sides of the cap b and trough c under this end. See Fig. 86.

If the roof is very flat, drips should be used at the end of each sheet, as described and shown for lead roofing in Fig. 82. The lower edge of the sheets, next to the eaves, should be strengthened by turning or doubling it back so as to form a bead, or by locking it to the gutter edge, where it joins the roof.

Standing Seam

Same as described and shown for tin roofing. See Fig. 49.

Corrugated zinc is laid with the flutes running up and down the incline. The sheets overlap to the extent of one corrugation at the sides, and 4 inches at the ends where connections are made. This method is shown under galvanized-iron roofing.

Standing Seam 315

Fig. 85.

Standing Seam 316

Fig. 86.

Ridge caps or rolls should have the edges a, Fig. 87, turned up and under, to make a strong edge, and should be secured in place by slipping the edge over the clips b, which are placed at intervals of 15 inches and nailed to the ridge. The cross-seams, where the lengths of the caps meet, are closed with a single lock seam. Flashings for Chimneys, etc. - The same as for other metal roofs, save that no other metal but zinc should be used, on account of the great difference in the expansion and contraction.

111. The gauge, thickness, and weight per superficial foot of zinc used for roofing purposes, are given in the following table:

Standing Seam 317

Fig. 87.

Table 14

Gauge Number.

Thickness. Inches.

Weight.

Ounces per

Square

Foot.

13

.0311

10

14

.0457

12

15

.0534

14

16

.0611

16

17

.0686

18

18

.0761

20