Figure 3-8.-Simple cornice.Figure 3-9.-Open cornice.CORNICESThe type of cornice required for a particularstructure is indicated on the wall sections of thedrawings, and there are usually cornice detail drawingsas well. A roof with no rafter overhang or cave usuallyhas the simple cornice shown in figure 3-8. This corniceconsists of a single strip or board called a frieze. It isbeveled on the upper edge to fit under the overhang orcave and rabbeted on the lower edge to overlap the upperedge of the top course of siding. If trim is used, it usuallyconsists of molding placed as shown in figure 3-8.Molding trim in this position is called crown molding.Figure 3-10.-Closed cornices: A. Flat boxed cornice; B. Slopedboxed cornice.A roof with a rafter overhang may have an opencornice or a closed (also called a box) cornice. Inopen-cornice construction (fig. 3-9), the undersides ofthe rafters and roof sheathing are exposed. A nailingheader (fascia backer) is nailed to the tail ends of therafters to provide a straight and solid nailing base for thefascia board. Most spaces between the rafters areblocked off. Some spaces are left open (and screened)to allow attic ventilation. Usually, a frieze board is nailedto the wall below the rafters. Sometimes the frieze boardis notched between the rafters and molding is nailed overit. Molding trim in this position is called bed molding.In closed-cornice construction, the bottom of the roofoverhang is closed off. The two most common types ofclosed cornices are the flat boxed cornice and the slopedboxed cornice (shown in figure 3-10, views A and B,respectively).3-9
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