8/26/13 Man-Day Estimates and Durations
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Naval Construction Force/Seabee 1&C -
Construction manual for building
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Table 2-1.Production Efficiency Guide
Factor Chart
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description of each master activity, it will be clear to
all where each work element falls. A good narrative
description reduces the chance of omitting any work
items from the estimate. Master activities for a typical
building might look like the following:
10XX Sitework
20XX Underslab Utilities
30XX Foundation and Slab
40XX Walls
50XX Roof
60XX Rough Utilities
70XX Interior Finish
80XX Finish Utilities
90XX Exterior Finish
Construction Activities
As the crew leader, you must break the master
activities into construction activities. The work
element checklist contained in appendix A to the
NAVFAC P-405, Seabee Planners and Estimators
Handbook, is a good guide for the development of the
construction activity list. A typical Naval Mobile
Construction Battalion (NMCB) project might contain
between 15 and 50 construction activities. Construc-
tion activity numbers are usually four digits. The first
two digits identify the master activity and the second
two digits show a specific construction activity within
a master activity. The number also includes a prefix
assigned by Ops that identifies the specific project.
Looking at the list of master activities example, this
project could have a construction activity for Pull
Wire numbered 6025. The number 60 represents
master activity Rough Utilities and 25 distinguishes
Pull Wire from other construction activities in that
same master activity.
and reporting are always done in 8-hour man-days,
regardless of the length of the workday.
MDs = QTY of WORK UNIT SIZE x MHRS PER
UNIT 8 x DF
For example, to install 16,000 SF of 1/2-inch drywall
over wall studs would require how many man-days?
(See page 4-78 of the P-405.)
MDs = 16,000 SF 1000 SF x 33 MHRS 8 = 66 x DF
Production Efficiency Factors
Production efficiency factors are the first step in
adjusting man-day estimates based on your unique
circumstances. The intent of a production efficiency
factor is to adjust for factors that will make you more
or less productive than the average Seabee. In
calculating a production efficiency factor, consider
only those factors that affect the crew while on the
job. Table 2-1 has listed eight production elements in
the far-left column. You need to consider the impact
of each of these production elements on each activity
given a specific crew, location, equipment condition,
and such. You need to assign a production factor
between 25 (low production) and 100 (high produc-
tion) for each element. A production factor of 67 is
considered average. Average these eight factors to
figure your production efficiency factor (PEF).
Delay Factors
Before you can adjust the man-day estimate, you
must convert the production efficiency factor to a
delay factor. You can find the delay factor by dividing
67 (the average production factor) by the production
efficiency factor (DF = 67/63.6 = 1.05). (See table
2-1.) Using the delay factor of 1.05 you now can adjust
the original man-day estimate.
66 x 1.05 = 69.3 or 70 MD
MAN-DAY ESTIMATES AND DURATIONS
You need to know how to calculate mandays and
duration for each construction activity, The P-405 is
the primary reference for Seabee man-day estimates.
This mathematical procedure has limitations. If
for example you are working outside in extremely bad
weather, and all other factors are considered average
(weather = 25, all others = 67), you would obtain a
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the primary reference for Seabee man-day estimates.
The P-405 lists how many man-hours it takes to do one
unit of work, The size of the unit is also given. The
quantity of work is divided by the unit size and
multiplied by the man-hours required to do one unit.
You then divide by 8 man-hours per man-day and
multiply by a delay factor (DF). Tasking, estimating,
(weather = 25, all others = 67), you would obtain a
production efficiency factor of 62 and a delay factor
of 1.08. This 8 percent increase in the man-day
estimate would not adequately compensate for
working in extreme weather. You are not limited to
the method of delay factors in the P-405. Use common
sense when impacted by extreme circumstances.
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