=1. Scope of Subject.=—The art of estimating is very important both to
the architect and to the builder; to the latter, in that he must employ
some systematic method of estimating in order to carry on his business
successfully, and to the former for the reason that he should at all
times be able to estimate the cost of the buildings that he designs.
The science—for such it is—of fixing prices on a piece of work in any
branch of the building trades must be based on an extended experience.
With a little practice, any one can learn to take off the quantities
of materials, but when it comes to determining the rates, only persons
having extensive and varied knowledge of building and costs of various
details can accurately estimate the time and labor required to
complete the work. In order, then, that the duties and requirements
of a practical estimator may be thoroughly understood, a number of
detailed estimates will be given in this Section as guides. It should
be remembered, however, that as the prices of materials and labor vary
from those assumed, so will the estimates vary. The information given
in detail should be considered only as a general guide in analyzing the
elements that enter into the constructive problems in each department
of the building trades. In this way it will be possible to determine
intelligently the various unit costs. The estimates given are, in
general, net figures, and do not include any contractor’s profit.
=2. Qualifications of the Estimator.=—In the United States, there are
no standard or definite rules on estimating that hold good in every
section. The builders of each locality have their own ideas and customs
regarding the subject. This fact, together with the difference in the
cost of labor in various parts of the country and the fluctuations
in the market price of materials, requires, as before remarked, that
a competent estimator be a man of long and varied experience in the
business. There are, however, certain practical rules and suggestions
that will materially assist in taking off the quantities and in valuing
the labor required for any building operation. These points will
therefore be taken up and considered in detail in this Section.
=3. Important Factors.=—The prime considerations in making an estimate
are accuracy and time. To these ends the estimator must systematize
his efforts, and endeavor to do a maximum amount of work in a minimum
amount of time. This, however, should not be done at the expense of
accuracy, for accuracy is the most important factor and is only insured
when the figures are carefully checked. The estimator, therefore,
while avoiding too great refinements in calculation, should aim at
correctness rather than at speed in doing the work. Very frequently
do the effects of haste and inaccuracy in estimating the cost of a
structure become evident when it is too late to remedy the errors,
resulting sometimes in the financial ruin of the builder that trusts
too implicitly in the estimator’s figures.
A record should be kept of all estimates made, as this kind of
information is most valuable and establishes a precedent on which to
base subsequent estimates, as well as a check on the work at hand.