Figure 2-25.-Setting up and bracing a ridgeboard when only a few workers are available.called collar ties (fig. 2-23). In a finished attic, the tiesmay also function as ceiling joists.To find the line length of a collar tie, divide theamount of drop of the tie in inches by the unit of rise ofthe common rafter. This will equal one-half the lengthof the tie in feet. Double the result for the actual length.The formula is as follows: Drop in inches times 2,divided by unit or rise, equals the length in feet.The length of the collar tie depends on whether thedrop is measured to the top or bottom edge of the collartie (fig. 2-23). The tie must fit the slope of the roof. Toobtain this angle, use the framing square. Hold the unitof run and the unit of rise of the common rafter. Markand cut on the unit of run side (fig. 2-24).METHODS OF RIDGE BOARD ASSEM-BLY.— Several different methods exist for setting upthe ridgeboard and attaching the rafters to it. When onlya few Builders are present, the most convenientprocedure is to set the ridgeboard to its required height(total rise) and hold it in place with temporary verticalprops (fig. 2-25). The rafters can then be nailed to theridgeboard and the top wall plates.Plywood panels should be laid on top of the ceilingjoists where the framing will take place. The panelsprovide safe and comfortable footing. They also providea place to put tools and materials.Common rafter overhang can be laid out and cutbefore the rafters are set in place. However, manyBuilders prefer to cut the overhang after the rafters arefastened to the ridgeboard and wall plates. A line issnapped from one end of the building to the other, andthe tail plumb line is marked with a sliding T-bevel, alsocalled a bevel square. These procedures are shown infigure 2-26. The rafters are then cut with a circular saw.Figure 2-26.-Snapping a line and marking plumb cuts for agable-end overhang.2-17
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