This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
The taking-off of quantities and making-up of an actual estimate, is the end toward which our efforts are now directed. This is done, as has been said, in a number of ways, no two persons arriving at the same conclusion or following exactly the same methods. To give the student a practical idea of how estimates are made, we shall now demonstrate the method of procedure in an actual instance. For this purpose, we shall take the case of the wooden Colonial residence of which the plans and working drawings, and the method of making these, are fully described in the course on "Architectural Drawing," and of which the details are also described to a certain extent in the chapters on "Building Superintendence;" and shall proceed at once to take off the quantities and make up an estimate of cost.
Method. The usual method followed is to take off the quantities in the order in which they occur in the specification or in the operation of building, beginning with the Excavation and ending with the Painting.
Two methods of procedure are open to the Contractor, which he may avail himself of according to his experience or confidence. He may take off simply his own particular branch of the work, relying on each sub-contractor to give him a price for the detailed portions of the work; or, if he is a general contractor, he may, with the requisite knowledge of general building operations, take off all the quantities, pricing them according to his knowledge, and may submit his proposition on the basis of his own figures. The latter method requires great experience and is followed generally by large contractors, who have in their employ men whose business is mainly to take off quantities and make up estimates.
The following estimate has been carefully made up on the basis of the data given in Part I as to prices of materials and labor. In actual practice, details of more or less importance will vary in different localities and among different contractors; but the example here given illustrates the process fully.