Estimating in Building Construction

Concrete 107

EXAMPLE 10-14 LABOR COSTS FOR CONTINUOUS
FOOTINGS

Determine the labor cost for placing the reinforcing steel for the
continuous footings (refer to Figure 10.26).

(4,298 pounds/2,000 pounds/ton)

hours/ton

/hour

Figure 9–27 is a complete estimate for the reinforcing found in the
building in Appendix A. 

10–4 Vapor Retarder

The vapor retarder or barrier is placed between the gravel
and the slab poured on it and is usually included in the con-
crete portion of the takeoff. This vapor barrier most com-
monly consists of polyethylene films or kraft papers. The
polyethylene films are designated by the required mil thick-
ness (usually 4 or 6 mil). The material used should be lapped
about 6 inches, so an allowance for this must be made
depending on the widths available. Polyethylene rolls are
available in widths of 3, 4, 6, 8, 10, 12, 16, 18, and 20 feet, and
are 100 feet long. Careful planning can significantly cut
down on waste, which should average 5 percent plus lapping.
Two workers can place 1,000 sf of vapor barrier on the gravel
in about one hour, including the time required to get the
material from storage and place and secure it. Large areas
can be covered in proportionately less time.
Vapor retarders are part of CSI Division 7, Thermal and
Moisture Protection (Chapter 13). They are included here
since they are part of the concrete slab takeoff.

Labor cost$459

Labor cost32 .2 hours$14 .25

Labor hours32.2 labor hours

15 labor

Labor hours

Estimating Vapor Retarder. The most accurate

method of determining the vapor barrier is to sketch a lay-

out of how it might be placed on the job (Figure 10.28).

Often several sketches must be made, trying rolls of vari-

ous sizes before the most economical arrangement is

determined.

EXAMPLE 10-15 VAPOR RETARDER (BARRIER)



Labor. The time required for the installation of the

vapor barrier has been estimated from the data presented

in Figure 10.29. The hourly wages are based on local labor

and union conditions; for this example, the wage is $9.25

per hour.

Labor cost7.2 hours$9.25 per hour$66.60

Labor hours7.2 hours

1 labor hour per thousand sf

Labor hours7.2 thousand sf (actual)

16 ¿ wide (total) 143 ¿ 52 ¿ 195 ¿Use 2 rolls 3,200 sf

16 ¿ wide (basement) 26 ¿ 26 ¿ 52 ¿

16 ¿ wide (main level) 24 ¿ 24 ¿ 60 ¿ 35 ¿ 143 ¿

20 ¿ wide (main level) 60 ¿ 60 ¿ 120 ¿Use 2 rolls 4,000 sf

FIGURE 10.28.Vapor Retarder Layout.

FIGURE 10.29.Vapor Barrier Labor Productivity Rates.

Sq. Ft. of Labor Hours per

Vapor Barrier 1,000 Sq. Ft.

Up to 1,000 1.5

1,000 to 5,000 1.25

Over 5,000 1