Fig. 37. When a roof surface is covered with gravel or slag a device called a "gravel-stop," shown in Fig. 37, is used. It is made of copper and applied along the edge of the roof and secured at the side and top. A brass edge-strip (described in detail on page 54) is fastened to the edge of the roof. The copper is hooked over this strip and brought up over the edge and out on the roof with a "crimp" above the roof surface to keep the gravel in place. The copper should extend out on the roof on top of the felt 4 inches and be nailed through the felt to the roof sheathing with copper nails and then covered with two layers of felt.

   The metal may also be laid in between the layers of felt instead of on top, or it may be laid on top of the felt and covered with two additional layers of felt extending 6 inches out on the roof as described in Fig. 40. Many roofers prefer this method as it prevents interruption of the roofing work.

   THE COPPER SHOULD NEVER BE LAID DIRECTLY ON THE ROOF BOARDS. The felt will pull away from the copper and an open joint result at the junction of the copper and the felt.

Fig. 38. When a flat deck covered by a copper roof is built over a sloping shingle roof the edge of the deck is flashed in the manner shown in Fig. 38. The flashing should lap the shingles 4 inches and be joined to the copper roofing by a flat lock seam with the seam turned in the direction of the flow.

Fig. 39. A gravel-stop flashing at the edge of a roof laid on a concrete slab is secured as shown in Fig. 39. Holes are drilled into the slab about 12 inches apart and ⅜ inch in diameter and a small cylinder of sheet lead slightly shorter than the depth of the hole is inserted. A brass wood-screw with a slotted washer is then used to fasten the copper to the concrete, as shown in detail in Fig. 63.

Fig. 40. A flat deck covered with felt-and-gravel roofing above a sloping shingle roof, is flashed as shown in Fig. 40. The lower edge of the copper is turned back on itself ½ inch for stiffness, and should lap the shingles at least 4 inches. It is brought up on to the main roof and, after forming a crimp to retain the gravel, is extended out on the roofing 4 inches and nailed about 8 inches apart near the inside edge, through the felt into the roof sheathing. The joint between metal and felt is made tight as described in Fig. 37.

   If the vertical distance from the shingles to the top of the crimp is more than 8 inches it may be advisable to make the flashing in 2 pieces joined by a flat lock seam secured by cleats to the vertical surface of the roof boards.

Fig. 41. When clay roof tiles are used on a sloping concrete slab roof and project but little beyond the eaves, the use of flashing is necessary. It is placed in the manner shown in Fig. 41. Sometimes this flashing takes a molded form and is treated in the design as a cornice, but the method of application is still essentially that shown in Fig. 41, except that the copper may be formed in two parts with a horizontal lock seam joining the parts at or near the first horizontal sleeper. The first step in placing the flashing shown in Fig. 41 is to secure to the concrete a brass edge-strip. This is done by drilling holes in the concrete about 12 inches apart and fastening the brass edge-strip as described in Figs. 39 and 63. The holes in the concrete should never be filled with wood plugs as the wood will dry out and shrink and the edge-strip will work loose. The flashing is brought up on the wall and turned back over the first sleeper and up on the roof far enough so that no water-pocket will be formed and the high end of the flashing will be about 2 inches vertically above the top of the first sleeper. No nailing is necessary for this part of the flashing as the weight of the tiles will hold it in place, but copper nails should be used to secure the tiles to the sleepers.

Fig. 42 shows three types of Hip or Ridge Flashings. It should be noted that the methods are to a large extent interchangeable. For instance, the brass straps shown in the upper right-hand corner can be used with either of the other two methods.

   When a low ridge-flashing without any projecting roll is desired it can be made as shown in the upper left-hand corner. The ridge boards covering the shingles are secured to the roof by nailing to blocks placed at intervals on the sheathing (the shingles being cut to fit around), or on a continuous block formed of ⅞-inch strips. After the shingles are laid the ridge boards are placed over them as shown, and are covered by the flashing piece. This is secured to the edge of the ridge boards by nails, as shown, or by brass wood screws. The flashing is given a slight projection (about 1 inch), which is bent down to the shingles after the nailing is done. This sheds the water and covers the nail holes.

   The method shown in the upper right-hand corner requires a specially shaped ridge-piece to take the flashing roll. The roll is secured by screws in the sides as shown, and the apron, if over 4 inches wide, should be stiffened against wind action by brass clamps or straps, spaced about 30 inches apart. These straps are secured by screws through counter-sunk holes as indicated, or are sometimes soldered to the apron. If placed under the apron they are riveted to it before the piece is set in position.

   The method shown in the lower left-hand corner requires no special shaping of the ridge-board, and is an excellent way of securing a large ridge roll. The board keeps the metal in place and it is set so that it can be fastened by screws in the ridge-board, making it unnecessary to drill the shingles or slates.

   Perhaps the simplest method is to use stock ridge and hip rolls. These are made of hard (cornice temper) copper in sizes up to 3-inch roll and 3½-inch apron. They are fastened by brass screws set through washers into holes drilled in the shingles or located above the upper edge. They require no ridge-board. When these are used the screw-heads should be soldered. On hips small pieces of copper should be built in with the shingle courses to prevent water working under the edge of the apron and thence under the shingles.

   Elaborate ornamented or molded rolls require special bracings and fastenings, and each case should be specially considered.

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