rates from a database, the estimator must determine whether
the retrieved data are appropriate for the current estimate. If
job conditions are different for the job being estimated than
typical conditions, the estimator must make the appropriate
adjustment to the price or productivity. To help avoid these
errors, the estimator must have a strong understanding of
estimating concepts and processes. She must look at each
number the software has prepared and ask herself, “Does this
number make sense?”
The second danger is to use the software for a project
that it was not designed to estimate. For example, one may
prepare a spreadsheet to estimate the installation of a water-
line up to a depth of four feet. If this spreadsheet were to be
used on a project where the waterline was at eight feet deep,
the software would underestimate the cost of the waterline
because additional safety measures would be required for
the additional depth. When using estimating software, it is
important for estimators to understand the intended use
and limitation of the software. It is also good to understand
the methodology used by the software to calculate quantities
and costs.
Estimating software can be divided into three broad
categories: spreadsheets, specialized estimating software,
and takeoff software. These are discussed in the following
sections.
5–3 Spreadsheets
Spreadsheet software, such as Microsoft Excel, is a powerful
tool for the construction estimator. Its usage ranges from
simple spreadsheets that are used to add up quantities to
complex spreadsheets that take hundreds of hours to
develop and continue evolving over time. Spreadsheets are
often used to augment specialized estimating software pack-
ages. In 2003, the American Society of Professional Estima-
tors reported that 29 percent of construction companies
used Excel as an estimating tool.^1
Excel and other spreadsheets have many advantages. If
they are not already available on the estimator’s computer,
they can be purchased cheaply. They are easy to use and can
be readily adapted to the company’s existing style. For a
company that uses paper forms, the forms can simply be
converted to a spreadsheet by creating the form’s layout in
the spreadsheet and then by adding the formulas needed to
perform the mathematical calculations. Spreadsheets can
make simple decisions by using IF functions. Simple data-
bases can also be integrated into the spreadsheet.
There are many examples of estimating spreadsheets
throughout this book, and sample spreadsheets have been
included on the companion disk. The Warehouse.xls spread-
sheet on the companion disk incorporates both IF functions
to make simple decisions and a simple database.
5–4 SPECIALIZED
ESTIMATING SOFTWARE
In 2003, the American Society of Professional Estimators
reported that 47 percent of construction companies used
specialized estimating software, such as WinEst or Timber-
line.^2 These estimating software packages use a spreadsheet
layout for the estimate, similar to what you would see in
Excel (Figure 5.1), and combine it with a database (Fig-
ure 5.2). The spreadsheet layout displays the costs associated
with each bid item in table format. These items are selected
from items in the database. The database contains standard
costs, productivity rates, labor rates, crews, and so on for
each item. When selecting items from the database, the esti-
mator must verify that the data selected are appropriate for
the project he is bidding. The costs shown on the spread-
sheet layout are summarized on a totals page (Figure 5.3).
The features available vary from software to software, and
some software allows you to select additional options or add
on modules.
Specialized estimating software packages can increase
the productivity of the estimator. They have the following
advantages:- They can take off a group of items (an assembly) at the
same time. For example, all of the components of an
interior wall (studs, track, sound insulation, drywall,
paint, and base) can be taken off by entering the length
and the height of the wall. The software then uses for-
mulas to determine the materials needed (the number
of studs, length of track, rolls of insulation, sheets of
drywall, gallons of drywall mud, pounds of screws, gal-
lons of paint, etc.) and the labor and equipment needed
to install them. - The estimate can be easily and quickly viewed in differ-
ent formats. For example, the sales tax can be listed on
the totals page or be spread out over the individual
items. Different formats can be used to print the esti-
mate. You can present one format to your boss and
another to the client with little preparation time. - The software can prepare standard and custom reports,
such as materials lists. - Changes can be made quickly to the estimates.
The disadvantage of specialized estimating software is
that they are expensive and require a substantial commit-
ment to set up and maintain them. They are useful for com-
panies that do a lot of estimating. For companies that
perform a low volume of estimating, the time it takes to
maintain a specialized estimating software often exceeds the
time it takes to perform the estimating, using Excel or paper
forms. These companies often abandon specialized estimat-
ing software after a short while.
An educational version of WinEst is included on the
companion disk.
Computers in Estimating 39(^1) American Society of Professional Estimators, 2003 ASPE Cost Estimating
Software Survey, posted on http://www.aspenational.com/cgi-bin/coranto/
viewnews.cgi?id=epzkzkupuyhepgiait&tmpl=fullstory&style=fullstory,
downloaded February 4, 2004.
(^2) Ibid.