Copper Flashings - A Manual - 1925 - Page 4
Fig. 5. When two adjoining slopes of a roof deliver unequal quantities of water to a valley, the larger quantity of water may force the smaller quantity back on itself and up beyond the top of the flashing. To prevent this a 1 inch crimp is sometimes put in the copper at the bottom of the valley. This breaks the force of water and prevents it from ascending the opposite slope.
Instead of the crimp shown an angle, or a Tee, formed of copper, may be used. It is soldered to the valley sheet on the slope opposite the one which delivers the larger quantity of water.
Fig. 6. In the construction of open valleys care should be taken to extend the copper flashing far enough up under the shingles so that the copper will be covered by at least two thicknesses of shingles as shown in Fig. 6. A larger detail of the cleats and the manner of fastening is shown on page 51 of the text.
Fig. 7. The return on the upper edge of the flashing and the "fold-over" are shown in Fig. 7. A slight opening shows between the layers of metal. This has been done in order to clearly illustrate the method employed. In practice the metal should be pressed together in both these places. This insures an even ridge for the shingles to rest upon. A larger detail of the method of cleating is shown in the text on page 51. The advantage of this type of valley is that the "fold-over" provides a means of expansion for the copper.
Figs. 8 and 10. Flashings for a wood window frame in a stud wall are shown in Figs. 8 and 10.
Fig. 8 shows two methods of flashing the window head. The left-hand drawing shows the edge of the flashing covered by the molding. At the right it is shown fastened by nailing along the exposed edge. Both methods are good. The flashing is placed after the frame and outside trim has been set but before shingling. It should be carried up on the wall at least 3 inches (but must always be covered by at least two thicknesses of shingles). A better fastening for the exposed edge shown in the right-hand drawing is by means of the edge-strip illustrated in Fig. 12 and on page 54 of the text- This is especially recommended when the trim has considerable projection or when an uneven row of nails on the upper edge of the trim would be unsightly.
Figure 10 shows the method employed for flashing the sill. The flashing is set after the sheathing is in position but before the window frame is placed. It should extend 4 inches out on the roof and as far as possible up under the sill. After the window frame is set it should be secured to the sill with copper nails. The edge should be turned back on itself ½ inch and after the shingles are placed turned down on the shingles.
Another method of securing this flashing is by nailing along the upper edge under the shingles and turning the lower edge at a sharp angle so that it presses tightly against the top fillet of the molding.
Fig. 9. Certain fundamental precautions to be observed in the construction of all valley flashings are enumerated in Fig. 9. A large detail showing the manner of forming cleats and securing them to the copper sheets and to the roof is more fully illustrated in the text on page 51.
Fig. 11. When a wood window or door sill is set on a stone or concrete sill an open joint between the two sills, where rain or wind can enter, must be avoided. To prevent this a water-bar of 20-ounce copper 2 inches or more wide is set in the wood sill. A reglet is cut in the stone sill and filled just before the wood sill is placed with pitch or other waterproofing compound. The wood sill with the projecting water-bar is set in this compound.
Fig. 12. At the base of a frame building where a projection (sometimes called a water-table) is formed the upper surface is protected by copper flashing in the manner shown in Fig. 12. A brass edge-strip is first secured to the wood by brass screws or nails and the copper flashing hooked over this strip and extended up on the sheathing and secured by copper nails not more than 8 inches apart along the upper edge. A cheaper and less efficient method of fastening is by nailing along the lower edge only. In either case a drip should be provided to prevent rotting of the wood work. Four inches up on the sheathing are sufficient when the shingles are doubled at the bottom of the wall but more is needed if shingles are but single course and the copper must be covered by the second course. The manner of applying the brass edge-strip is described on page 54 of the text.
Fig. 13. When a shingle roof abuts a shingle wall the copper flashing is arranged as shown in Fig. 13. This flashing should be extended 4 inches out on the roof over the shingles and up on the wall sheathing at least 4 inches and secured along the upper edge by copper nails. Note the ½-inch "fold-over" of the lower edge.
Fig. 14. When a felt or other laminated roof abuts a wall covered with stucco the detail shown in Fig. 14 is used. An extra board may be placed on the sheathing as shown to bring the flashing out to the face stucco. The lath should lap the cap flashing at least 1 inch. The base flashing should extend out on top of the roofing material at least 4 inches and be nailed to the roofing boards. Two additional layers of the roofing material should then be placed on top of the base flashing after the flashing has been well swabbed with pitch. Base flashing should extend up far enough to allow a 4-inch lap of the cap flashing. The lower edge of the cap flashing should be turned back on itself ½ inch.
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