Fig. 461 represents a plan of a roof, and will show most of the positions in which lead is used on a roof, the letters on the plan referring to the following members: A, a ridge; B, a hip; C, a valley; D, a flat; E and F, gutters between two roofs; G, gutters behind a parapet; H, a cesspool; L, a roll; M, a drip; N, a gutter behind a chimney; P, an apron in front of a chimney; Q, the parapet wall; R, the top of cornice; S, a gable where the flashings and secret gutter would be used; T, a step-flashing on the side of a chimney; V, junction of flat and roof; W, an iron eaves-gutter.
Following this key plan, we have, first, the ridge A, which is treated as fig. 462, a wood-roll 2 1/2 inches in diameter being secured by double-shouldered spikes to the ordinary ridge as shown; or nailed to a bevelled fillet secured to the ordinary ridge, as fig. 463, the object of which is to enable the plumber to be the better able to dress the lead under the roll, in order to form a key, so as to prevent the sun from drawing it off.
In practice, the bottom of the roll should be no less than 2 inches above the top of the ridge to allow for this key; and the wings or sides of the lead covering should extend 7 inches down the roof over the slates. The lead is put on in 7 or 8-feet lengths, with a 6-inch lap at the joints.and fastened down on the top (so that it has freedom to move elsewhere) by round-headed copper spikes, or by lead tags about 1 1/2 inches wide, fixed by copper nails, 2 or 3 feet apart, to the woodwork underneath, as fig. 464.
B. Hips are treated in section in a similar way to ridges, the difficulty at the junctions with the ridge being got over by the hips being dressed down first, and the ridge lapping over, as fig. 465; and the foot of the hip is bossed, as shown at the foot of the same figure, the roll itself stopping several inches off the eaves, and being rounded off for the lead to be dressed over as illustrated.
C. Valleys are internal angles, as opposed to hips, which are external. Fig. 466 represents a section of a valley; 5 inches of lead should be visible from the edge of the slate to the centre or angle of the valley, to allow a person to walk up them without breaking slates, and the lead should go 6 inches under the slates, and be nailed by copper nails, always over the tilter, and just turned up the roof, as shown. They are put on in 7 or 8-feet lengths, and, where a joint occurs, the bottom piece is copper-nailed 6 inches under the upper piece, which is dressed over similarly to fig. 467. A saddle-piece is used at the top, next the ridge, just as for hips, the valley-piece going 6 inches under the saddle-piece.
D. Flats, as the name implies, are roofs with small pitches which have to be covered with lead (or zinc), as slates and tiles are wholly unsuitable and ineffectual. The boards on which the lead is to be dressed should be laid "with the fall," so that there may be no projections and sharp edges across the fall to cause the lead to wear; and for the same reason they should be also of such thickness that there is no possibility of their warping.
The boards being laid according to the above principle, and to a fall of 1 1/2 inches to 2 inches in 10 feet, and as the lead should never be in more than 10-feet lengths at the outside, and that only in exceptional cases - 7 or 8-feet lengths are the best, and also the most economical, as the lead sheets are only 7 feet 9 inches wide, sizes above that length having to be cut lengthwise - the rolls to joint it are fixed at certain distances apart, usually 2 feet 10 1/2 inches from centre to centre, or about 32 inches apart, so arranged (for economy) that two widths can be cut without waste out of the width of a sheet 7 feet 9 inches wide; it is also unadvisable to have the lead in larger surfaces, in view of the sun's power over it.
These roils, fixed at the above distances apart, are used as a basis for the joint, one side of the sheet of lead going over and being secured by copper nails to one roll as X, on fig. 468; and the other side is lapped to a distance of 1 1/2 inches on the flat, over another sheet already treated as the first side. This, it will be seen, makes a complete covering, and allows the lead to expand, as it will be noticed that it is only fixed at one side, as X, the other being loose and dressed over the roll to keep it in position. The ridge and hips, on the fiat shown in fig. 461, are treated in exactly the same manner; the mitres being dealt with as fig. 469, one sheet lapping over the complete joint, covering up the other different sheets in a manner similar to the sections on fig. 468. The ends of the rolls are bossed similarly to hips.
The nose, or eaves, of the flat, on to the roof, is worked as fig. 470, the under-piece (called an apron) being dressed and copper-nailed into a rounded rebate worked on the boards across their grain, so that the top piece of lead may not be tilted up by the under-piece.