These fillets are used when the roof is covered with boards. The fillet is shaped as shown at a, Fig. 40, and extends the full length of the gutter. A number of strong cleats b are nailed to the roof and bent over the fillet. The gutter is then laid and the cleats are doubled back over the edge, as shown. This is considered first-class practice. The method of laying slates or shingles flat on sheet-metal gutters, valleys, flanks, or other flashings should never be followed. Water will work up between them by capillary attraction.

Fig. 39.

Fig. 40.