138 CHAPTERTWELVE
FIGURE 12.5.Structural Metals Quantification. FIGURE 12.4.Structural Metals Takeoff.12–4 Metal Joists
Metal joists,also referred to as open web steel joists,are pre-
fabricated lightweight trusses. Figure 12.6 shows various
types of metal joists. The weight per foot is typically found
in the manufacturer’s catalog. Figures 12.7 and 12.8 are
excerpts from a bar joist catalog that show weights and
anchoring.
To determine the quantity of bar joists, calculate the lin-
ear footage of joists required and multiply this number by its
weight per foot; the product represents the total weight. The
cost per pound is considerably greater than that for some
other types of steel (such as reinforcing bars or wide flange
shapes) due to the sophisticated shaping and fabrication
required.
Metal joists by themselves do not make an enclosed
structure—they are one part of an assembly. The other
materials included in this assembly are varied, and selection
may be made based on economy, appearance, sound con-
trol, fire-rating requirements, or any other criterion. When
doing the takeoff of joists, the estimator should be aware of
the other parts in the assembly; they must all be included
somewhere in the estimate. The mechanical and electrical
requirements are generally quite compatible with steel
joists; only large ducts have to be carefully planned for job
installation.Specifications. Specifications will list the type of joists
required, the type of attachment they will have to the rest of