This section is from the book "The Building Trades Pocketbook", by International Correspondence Schools. Also available from Amazon: Building Trades Pocketbook: a Handy Manual of reference on Building Construction.
In Fig. 4 is shown a strong and durable box gutter, suitable for either a frame building or for a brick or stone structure, having a wooden cornice. A series of lookouts are nailed to the wall studs (or built into the brickwork or stonework), forming a solid base for the cornice and gutter. The width of the lookouts may be varied, to obtain the grade for the gutter bed, or it may be uniform, strips being nailed to the upper edges of the pieces. On a gable roof the cover-plate over the crown mold should be kept in line with the sheathing on the roof slope. In lining this gutter, if a strip of hoop iron is tacked to the fillet of the crown mold, with its lower edge kept 1/4 in. below the mold, the lining may be tightly clasped over the strip, and face nailing dispensed with, thus making a neat and durable job.
The lining should pass behind the eave mold, but need not be carried up the slope.
The insertion of a triangular strip at the angle of the gutter bed and the wall is of advantage, as the gutter is more readily cleaned by the wash than with a square corner. The end of the gutter is closed at the gable, so that the crown mold can run up the facia and be continuous; it is usual to leave a space of from 4 to 6 in. between the closed end and the gable facia.
Figs. 5 and 6 show methods of forming standing gutters, the former being adapted for shingled roofs, and the latter for either shingle or slate roofs. It is important to insert the tilting fillet in both cases, for two reasons: First, to obtain the tilt for the lower double course so that the bed of the second course will lie close to the back of the lower course; and second, to form a drip at the edge of the lower course, so that water will not be drawn up by capillary attraction under the shingle or slate and pass over the upper edge of the flashing. These are durable forms of gutters, but they have the disadvantage of acting as guards, retain snow on the roof, and mar to some extent the appearance of the roof planes.
Trough gutters of wood, tin, or copper are frequently used, and where securely fastened in place, below the drip line of the roof covering, give good results. Gutters should have a pitch of 1/8 in. per lineal foot, wherever practicable, so that the bed of the gutter will be well cleansed during a rain fall. Where the pitch is less than stated, it is difficult to flush the dust out of the pockets formed by the "kinking" of the gutter lining.