11. The following terms are applied to express the different elements or details which exist in nearly all roofs: Span is the distance between the supports. Rise is the vertical distance between the ends of a slope. Run is the horizontal distance between the ends of a slope.

Pitch is the slope of the rafters as determined by both the rise and run.

The eaves are the lower part of the roof projecting over the walls.

A gable is that portion of a wall extending above the eaves; it is generally built to the shape of the roof abutting or covering it. Hips are the salient angles formed by the intersection of the roof slopes.

Valleys are the re-entrant angles formed by the intersections of the slopes. A close valley is that in which the material used in covering the roof is mitered and flashed at each course, no metal being exposed. Open valleys are formed by sheets of metal laid with a portion of their sides under the material used in covering the roof, and with the center part, or valley gutter, left exposed for a width of 4 or 5 inches on each slope.

The ridge is the line formed by the meeting of the slopes of the roof at its summit, or apex.

Saddles are small inverted V-shaped pieces of roof, placed at the backs of chimneys or other portions of a building, protruding through and above the roof. They serve the double purpose of shedding the water and preventing snow and ice from accumulating.

A cant is an angular-shaped piece of roof, used on flat-pitched roofs with parapet walls and placed at the lower end of the roof, commencing at a point at the leader head, and gradually running out on the roof, until, at the opposite end, it is 4 or 5 feet wide and extends up on the wall about a foot. It is also used back of bulkheads, etc. for the same purposes as the saddle.

Roofing 237

Fig. 14.

A curb, or combing, is a support for a skylight, or scuttle, and surrounds the opening cut in the roof.

A bulkhead is formed by a partition built around the openings cut into the roof for elevators, stairways, dumb waiters, and air-shafts. It is also occasionally applied to the vertical or sloped backing in the rear of the main cornice.

A tilting strip, or fillet, is a triangular strip of wood used to raise the flashing, shingles, slate, tile, etc. at the eaves, gable ends, around chimneys, skylights, bulkheads, and ventilators, oragainst parapet and gable walls, to prevent the accumulation of dust, water, or snow.