Copper Flashings - A Manual - 1925 - Page 10
Fig. 25. The method of flashing a copper ventilator set on a sloping shingle roof is shown in Fig. 25. The ventilator is fastened to the flashing by a soldered lap seam either before or after the ventilator is in place. When placed on the roof the flashing should lap the shingles on the sides and bottom from 6 to 8 inches and be formed over the edges. At the top the shingles lap over the copper, which should be carried up on the roof far enough so that the upper part of the sheet is covered by at least two thicknesses of shingles. The flashing is fastened to the roof sheathing by long brass woodscrews. To avoid breaking the shingles the holes for these screws should be drilled, not punched, and the screws set through slotted brass washers. Only 4 screws are shown in the illustration but if the ventilator is a large one more will be required. They should be spaced not over 12 inches apart. When completed the screw heads and washers should be well covered with solder. The lower edge of the flashing should be turned back on itself ½ inch for stiffness. Attention is called to the matter of "guying" as described in Fig. 26.
Another method of fastening this flashing is to place the sheet on a soft pine block and drive holes in it with a blunt nail-set — in effect a counter-sinking. After the sheet is in place on the roof ordinary wood screws are set through these holes and covered with solder.
Fig. 26. If the ventilator is placed on the ridge of the roof instead of the slope the detail shown in Fig. 26 is used. The method is similar to that described in Fig. 25 except that the flashing is entirely outside the shingles. In both cases (Figs. 25 and 26) in order to avoid strain on the flashing connections, if the ventilator be a tall one, it should be steadied by rods or wires secured to the roof. These rods or wires are fastened to the ventilator as near the top as possible by a brass collar and to the roof by brass screw-eyes or similar devices. The flashings for these consist of pieces of copper extending out on the roof about 8 inches on each side, and long enough to extend from the butts of the shingles next below up and under the shingles above as far as possible. The sheet is soldered to the shank of the fastening, or a thimble is fitted around the shank, soldered to the sheet, and filled with waterproofing-compound. These screw-eyes can also be flashed as described in Fig. 28.
Fig. 27. Vent- or other pipes through a roof are flashed as shown in Fig. 27. The lower edge of the flashing laps the shingles not less than 4 inches, but the sides and top are placed under the shingles and covered about 6 inches. If the flashing is over 12 inches wide the lower edge should be turned back on itself ½ inch. This stiffens the metal and prevents lifting by the wind. The flashing around the pipe should be flared out at the bottom and soldered to the roof sheet. It should extend up to the top of the pipe and be secured either by an iron cap screwed in place, as shown in Fig. 29, or by a copper cap, as shown in Fig. 30. (See description of these figures.) The flashing should be carried up above the top of the shingle course on which it rests and held in place by nailing along the upper edge.
Fig. 28. Many instances occur where the roof is pierced by steel members such as struts to hold a platform or similar structure. Great care should be used at these places not only to make the point of penetration water- and damp-proof but also to allow room for expansion and contraction of the steel. For this purpose the detail shown in Fig. 28 is recommended. The composition roof is laid in the usual way close to the steel and a copper collar is formed around the steel extending out on the roof 2 inches. The ends of the collar are lapped and soldered and the pan thus formed is filled with pitch or other waterproofing-compound. The steel should be heated with a torch to secure proper adhesion, especially in cold weather. The part extending out on the roof is covered with two layers of fabric, the copper having been first carefully swabbed with pitch. Where a tile roof is used the flashing is laid on top of the regular roof waterproofing. When it is necessary to make the vertical and horizontal parts of this pan in two pieces the joint between the parts should be a soldered lap seam.
Fig. 29. There are two methods of terminating the flashing when a vent-pipe comes through the roof. One method is shown in Fig. 29. The horizontal flashing is turned out over the roofing 6 inches. A copper sheet is placed around the pipe and soldered to the horizontal sheet. Some roofers coat the outside of the pipe with white lead or asphaltum before placing the flashing. The roof flashing is covered by two layers of roofing and the flashing on the pipe is held in place by a cap screwed on the top of the pipe and enclosing the flashing. Before placing this cap the threads are coated with white lead. This method is used only with screw-pipe.
There are on the market several practicable and satisfactory types of patented vent and pipe flashings for various kinds and conditions of roofing.
Fig. 30. Where cast-iron pipe is used the flashing is shown in Fig. 30. It may also be used for threaded pipe. The roof and vertical portions are constructed as described in Fig. 29 but the top of the vertical portion is held in place by a copper cap forced down over the pipe and the flashing. This cap should be 6 inches high and should project into the pipe at least 2 inches. The vertical flashing should be carried high enough so that the cap will lap at least 4 inches.
Fig. 31. Where a flag pole extends through the roof the flashing is shown in Fig. 31. The flashing is turned out on the roofing 6 inches. The copper collar around the pole is lapped over the base flashing and well-soldered. The collar and the flashing must be kept away from the pole to allow for vibration. A flared hood is then placed around the pole extending down so that it will lap the collar at least 3 inches. This hood is held by a brass band 1 inch wide set in white lead and bolted. The lower edge is turned back on itself ½ inch for stiffness. Very tall poles are usually braced by rods secured to a collar several feet up on the pole. The method of waterproofing the rods at the roof is similar to that described in Figs. 26 and 28.
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