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.
Introductory. The ability to estimate may be considered as the dividing line between the journeyman and the master builder, for, no matter how skilful a mechanic may become, he can never "hang out his shingle" and invite patronage in his distinctive line of work, unless he becomes able to make reliable estimates of material and labor to be furnished. To do this something more than mere accuracy and quickness in figures or a mastery of mathematics is needed; namely: experience and judgment, an understanding of the more or less complicated details which go to make up a building, and a knowledge of current prices and discounts in the trade. It is the object of this paper to point the way toward the acquirement of such of these needs as may be imparted by words or figures; that is, to put in condensed form some of the common methods by which estimates are made up, and to point out some of the things which are to be avoided.
Prices. As prices of labor and materials are constantly shifting, those quoted in this paper must be taken only as proportionate, to be used in comparison with known quantities and methods. All prices given are as current in Boston, Mass., in December, 1906, and are subject to immediate change. On account of the variableness in price of labor and materials, it is better, in general, to make estimates on the basis of days or hours, and quantities of materials, so that they may be used for comparison in future work. To this end all estimates should be carefully labelled and filed away for future reference. This should be done whether the bids were successful or otherwise. If a successful bid, there will arise a good opportunity to compare the estimates of cost of the different items, with the actual cost of execution; and if a bid fails to win the job, satisfaction and experience may be gained by noting the items which may have been priced too high or too low. This data may be of great service in preparing future estimates, especially in the comparisons between estimated and actually executed work.
* There is no such a thing as a universal or permanent standard price for anything. Prices vary in different localities at the same time and in the same locality at different times. The estimator must therefore acquaint himself with local market conditions in every case.
Catalogues. Catalogues and price lists of all standard articles are easily obtained and should be kept at hand, properly indexed, for ready reference, as they contain a great deal of specific information. For close figuring, however, it will not do to rely upon these prices, as the amounts of trade discounts are not always included. These vary greatly from time to time, and often there are two or more discounts, a trade discount, a cash discount, and a variation in discounts made by different merchants, all of which the contractor must become aware of to obtain bottom prices.
All data of this sort should be carefully tabulated for constant reference, in such a form that it may be easily revised and kept, so far as possible, up to date.
The manner and time of payments is a matter to be considered in this connection, as it will permit the contractor to take advantage of cash discounts, which often make a great difference in the cost of certain materials.
Profit. To the actual price of labor and materials must be added the profit and this will need careful consideration. A common method is to add a lump sum to the estimated cost of labor and materials, varying with locality and customer, with the probable sharpness of competition and the circumstances of the contractor. This is a careless method, as it leaves no means for future comparison and no certain knowledge of just what the profits of a given job are.
Percentage. A better way is to base the profits upon a percentage of the estimated cost. This will vary, in ordinary cases, from ten to fifteen per cent, ten per cent being the least that should be expected on any work, and this is not enough for small contracts of two or three thousand dollars; but for large work, where there is a great duplication of parts and processes, it will be enough in most cases. Some contractors, whose workmen are required to perform especially skilful labor, figure fifteen per cent on all labor and ten per cent on materials.
Duplicate Parts. The matter of duplication is an important factor in estimating, as a considerable saving is often made if large quantities of material, either worked or unworked, are required; this is especially true in manufactured parts, such as doors and windows, columns, balustrades, etc. Modern machines are capable of duplication with astonishing rapidity, and workmen can put together similar parts more quickly and cheaply than variable members.
Transportation. The distance of the work from the shop of the contractor, or from centers of manufacture, will affect the cost to a marked degree, as much time is consumed in teaming and especially in handling material a number of times.
If communication between the works and the building site can be established by water, it will usually save considerable expense for freight and handling, with perhaps less risk of damage, and consequently less expense for crating and boxing. A careful study should be made of the means of transportation to each different building site from the shop, the office, and the mill, and the data kept for future reference, subject to varying rates and conditions, to change of seasons, and amounts to be transported.
These are some of the more important matters which require preliminary consideration as affecting all estimates, and are only a small part of the real questions involved, as different localities and customs require different treatment, and numerous questions will arise to confront the contractor, all of which may be successfully met, as we have seen, by the exercise of care and judgment.
Methods. Estimates are formed by many and varying methods, depending upon the degree of accuracy required, the capability of the contractor, and the character of the building. A broad division may be made between approximate estimates and accurate detailed estimates, only the latter of which should be considered when it is the intention to actually carry out the work under a definite contract.