Fig. 105. Shingle Tins Fig. 106. Valley
Of the many ways of protecting the intersection of hip shingles when in place upon a roof, the simplest is that of employing tin shingles. Such shingles should be of sufficient length to allow the corners to be turned under as shown in [Fig. 105], and still extend far enough under the next course of shingles to permit the nails holding the tins to be covered. It is not good practice to nail thru these tins after the roof has been covered, that is, to place these tins after the roof has been shingled because the action of the weather "lifts" the nails when exposed thus.
Valleys are covered with a strip of metal to a width of 20 inches. Upon steep roofs and short valleys this width may be reduced to 16 inches. Space must be left between the edges of valley shingles as shown in Figs. [106] and [107]. The amount will depend upon the length of the valley and the steepness of the roof. For a ½ pitch with a length of twelve to fourteen feet of valley, the space at the top of the valley may well be 1 inch to each side of the valley center line, widening gradually toward the lower end to 2½ inches to each side. Chalk lines snapped upon the tin or other metal forming the valley indicate the location of shingle edges. Nails in valley shingles should be kept well back from the valley edge of the shingles.
Fig. 107. Shingling Valley
Flashing consists in placing tin shingles or other material about the members making up a joint so that the joint shall "turn water." Counterflashing consists in placing a double layer of tins in such a way as to doubly insure turning water from a joint.
[Fig. 108] is an illustration of flashing where shingles meet lap siding. Shingle tins are forced under the siding on one side and either under or over the shingles, several inches of lap being allowed all about.
[Fig. 109] illustrates a counterflashed chimney. A layer of tins is placed as in flashing against siding except their top edges are not inserted. Over these tins a second layer is placed as shown, the top edges being inserted ¾" between the layers of brick, the mortar being raked out so that this can be done. These turned edges are held in place by the insertion of a wedging nail or tack, after which the cracks are filled with cement, or better, an elastic roofing composition.
Tins should be carried high enough to prevent drifted snow from entering; 2½ or 3 inches at the narrowest place.
