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Greek: the ridge height is 1 ⁄ 9 to 1 ⁄ 7 the span (an angle of 12.5° to 16°); Roman: the ridge height is 2 ⁄ 9 to 1 ⁄ 3 the span (an angle of 24° to 34°); Common: the rafter length is 3 ⁄ 4 the span (about 48°); Gothic: the rafters equal the span (60°); and; Elizabethan: the rafters are longer than the span (more than 60°). [7]
Building codes in the U.S. specify ventilation rates as a minimum of 1 sq ft (0.093 m 2) of opening per 150 sq ft (14 m 2) (1:150) with a ratio of 1:300 in some conditions. [8] Warm air rises, so ceiling insulation is designed to have a higher r-value and the insulation is often installed between the ceiling joists or rafters.
Compass rafter: A rafter curved or bowed on the top (the top surface of a rafter is called its "back") or both the top and bottom surfaces. Curb rafter: The upper rafters in a curb (kerb, gambrel, Mansard roof) roof. Hip rafter (angle rafter): The rafter in the corners of a hip roof. The foot of a hip rafter lands on a dragon beam.
The hip or valley rafter also connects the ridge to the plate, but lies at a 45-degree angle to the common rafter. This number gives the length of the hip or valley rafter per seventeen units of run. Difference in lengths jacks. The jack rafters lie in the same plane as the common rafter but connect the top plate (the wall) or ridge board to ...
In solid mechanics and structural engineering, section modulus is a geometric property of a given cross-section used in the design of beams or flexural members.Other geometric properties used in design include: area for tension and shear, radius of gyration for compression, and second moment of area and polar second moment of area for stiffness.
The "hips" and hip rafters sit on an external corner of the building and rise to the ridge. Where the building has an internal corner, a valley makes the join between the sloping surfaces (and is underlain by a valley rafter). Hip roofs have the advantage of giving a compact, solid appearance to a structure. The roof pitch (slope) may vary.
Cutting speed may be defined as the rate at the workpiece surface, irrespective of the machining operation used. A cutting speed for mild steel of 100 ft/min is the same whether it is the speed of the cutter passing over the workpiece, such as in a turning operation, or the speed of the cutter moving past a workpiece, such as in a milling operation.
Key: 1: principal rafters, 2: collar beam, 3: arch braces. Lacking a tie beam, [ 11 ] the arch-braced (arched brace) [ 12 ] truss gives a more open look to the interior of the roof. The principal rafters are linked by a collar beam supported by a pair of arch braces, which stiffen the structure and help to transmit the weight of the roof down ...