This section is from the book "A Treatise On Architecture And Building Construction Vol3: Stair Building, Ornamental Ironwork, Roofing, Sheet-Metal Work, Electric-Light Wiring And Bellwork", by The Colliery Engineer Co.. Also available from Amazon: A Treatise On Architecture And Building Construction.
When coping blocks are used to surmount cornices, the flashing\ or wash of the crown may be extended through to the back of the wall, where it may connect to the roof covering, or to a gutter lining, as the case may be. When it is necessary, however, to entirely cover the blocking course with the same kind of metal as the cornice, the metal work of the cornice may be extended up and continued over the blocking course, as shown in Fig. 23; the sheets being crimped and held in place by cleats in the seams a, b, and c. A wooden wall cap is placed on top of the brickwork to protect the top course and take the cleat nails.
36. Stone cornices may be flashed as shown in Fig. 24. The copper is bent over the face of the stone and doubled over with a beaded edge on the under side to form a drip. This also prevents the flashing from rising in front. When the top surface is narrow - i. e., less than 12 inches - it does not need to be held down, but when it is wide, the copper should be held down with fastenings, as shown at a and b.
The arrangement shown in Fig. 24 is used at the junction between a stone cornice and an asphalt roof laid on fireproof construction, the asphalt covering being shown at c. Sometimes the copper is bent down flat over the back of the stone, but the best method of attaching it is to groove the stone at the back and let the copper into it, as shown at d. This holds down the flashing at the back.
37. The common method of fastening the sheet to the stone is to drill 1/2-inch or 5/8-inch holes at intervals over the surface of the stone. These holes should be cut wider at the bottom than at the top, so that the lead plugs cannot be pulled out. An iron rod, whose diameter is less than that of the screws to be used, is greased and placed upright in the hole. Molten lead is then poured around the rod until the hole is full.
The rod is then pulled out, and when the flashing is all laid and neatly set in place, it is screwed down to the lead plugs with brass screws.
Expansion bolts (see Fig. 25) are now generally used for fasteners. After the holes are drilled and the stone covered, the holes are "found" and the expansion bolts are inserted. A washer a is placed between the bolt head and the copper, and the bolt is screwed down tight. This draws up the tapered, or wedge-shaped, nut b and presses the sides c, c against the sides of the hole. A cone d is then soldered over the fastener, as shown, to make it water-tight. If fasteners are not used, the copper is likely to rattle when the wind blows.
38. Chimney caps are made in different styles. The most simple, and perhaps most common, form is a plain sheet-metal cap which is slipped down over the brickwork about 6 inches, the sides of the cap being nailed into the joints of the brickwork. A superior chimney cap, however, is shown at a, Fig. 26. The brick chimney is built up to the course b, then the cap is bedded on, and finally the brickwork c is filled in from the top, so that its weight on the flange, which is turned over the course d, will prevent the cap from being blown off. The moldings of the cap, being of small projection, do not require any lookouts. The brickwork must, however, be built up tight to the top of the cap to prevent it from settling down and flattening the molding.