Estimating in Building Construction

94 CHAPTER TEN

This sketch shows how the footing dimensions for side G were
determined. Figure 10.3 is a tabulation of all dimensions for the
3  2 -wide footings. One of the advantages of takeoff software is
that the estimator can measure the length of footings directly
off the plans, marking the footing and keep a running total as
she goes.

Volume of concrete (cy)39.6 cy1.0542 cy

Add 5 percent for waste and round off

Volume of concrete (cy)1,068> 27 39.6 cy

Volume of concrete (cy)cubic feet > 27

Volume of concrete (cf )3.167 sf337.3¿1,068 cf

Volume of concrete (cf)Cross-sectional area (sf )Length (ft)

Cross-sectional area (sf )3.167¿1.0¿3.167 sf

Cross-sectional area (sf ) 3 ¿ 2 –  1 ¿ 0 –

Cross-sectional area (sf )Width (ft)Height (ft)

FIGURE 10.3.Linear Feet of 3 2 -

Wide Continuous Footing. 

FIGURE 10.4.Spread Footing Detail. 

FIGURE 10.5.Cross-

Section of Drilled Pier.

EXAMPLE 10-2 SPREAD FOOTING

Drawing S8.1 detail 16 in Appendix A (Figure 10.4) of the small
commercial building details the one spread footing.
The concrete contained in this footing is found in virtually the
same fashion, as was the continuous footing.

Use 1 cy

Volume of concrete (cy)0.33 cy1.050.35 cy

Add 5 percent for waste and round off

Volume of concrete (cy)9 cf>27 cf per cy0.33 cy

Volume of concrete (cf ) 3 ¿ 0 –  3 ¿ 0 –  1 ¿ 0 – 9 cf

Volume of concrete (cf )Length (ft)Width (ft)Height (ft)

Drilled Piers. When dealing with drilled piers, some
information about the soil is needed. If the soils are loose
or the water table is high, it may be necessary to case the
piers. The casing prevents the sides from caving in and
water from seeping in. The casing, if steel, is typically
removed as the concrete is placed; however, heavy-duty
cardboard tubes can be used as casing. If this type of mate-
rial is used, it is left in place and will eventually deteriorate.
In clay soils, which are cohesive and impermeable, casings
are rarely required.
To quantify a drilled pier, as shown in Figure 10.5, the
shaft diameter, bell diameter, and angle of the bell must be
known. The volume of the drilled piers can be calculated, or
tables similar to the ones found in Figure 10.6 could be used
to find the volume. If the volume is to be manually calcu-
lated, the bell diameter and angle can be used to find the
height of the bell by using Formula 10-1 or 10-2. Then the
volume of the bell is found using Formula 10-3 or 10-4,
which is added to the volume of the shaft (Formula 10-5) to
determine the volume for a specific pier.