Roof Slope

Figure 1-67.Constructing a typical ceiling frame.

Builder 3&2 Volume 02 - Construction manual for building structures
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Figure 1-64.—Ribband installation. in the same direction as the rafters, as shown in with two 16d nails to the top of each ceiling joist, as figure 1-62. The 2 by 4s should be nailed to the top of shown in figure 1-65. The strongbacks are blocked up each ceiling joist with two 16d nails. The 2 by 4 pieces and supported over the outside walls and interior should be spaced no more than 4 feet apart, and the ends partitions. Each strongback holds a ceiling joist in line secured to the heels of the rafters or to blocking over the and also helps support the joist at the center of its span. outside walls. Roof Slope When ceiling joists run in the same direction as the roof rafters, the outside ends must be cut to the slope of the roof. Ceiling frames are sometimes constructed with stub joists (fig. 1-63). Stub joists are necessary when, in certain sections of the roof, rafters and ceiling joists do not run in the same direction. For example, a low-pitched hip roof requires stub joists in the hip section of the roof. Ribbands and Strongbacks Ceiling joists not supporting a floor above require no header joists or blocking. Without the additional header joists, however, ceiling joists may twist or bow at the centers of their span. To help prevent this, nail a 1 by 4 piece called a ribband at the center of the spans (fig. 1-64). The ribband is laid flat and fastened to the top of each joist with two 8d nails. The end of each ribband is secured to the outside walls of the building. A more effective method of preventing twisting or bowing of the ceiling joists is to use a strongback. A strongback is made of 2 by 6 or 2 by 8 material nailed to the side of a 2 by 4 piece. The 2 by 4 piece is fastened Figure 1-65.—Strongback. 1-37

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