The book, Modern Plumbing Illustrated by R. M. Starbuck provides suggestions for estimating plumbing construction in detail. Estimators require great precision in their estimating of labor and material. The plumber requires to keep a close account of these things and should know when the work will be complete. It is essential to include items like gasoline, screws, putty, freight, cartage, etc. to ensure the accuracy of the estimate.
Successful plumbing firms follow an organized system of estimating, and keep a close account of all stock and labor used on each contract, thus being able to figure exactly the amount of profit or loss on any completed piece of work. There are various other firms that, while estimating accurately and safely on stock and labor items, do not figure any percentage into their contracts to cover inside expenses, like rent, office expenses, telephone, etc.
The expense of conducting business is a matter which must be figured largely by looking into those expenses of the past, and from the comparison of this amount with the gross amount of business done, the percentage that must be allowed for the conducting of business may be arrived at. Thus, if it costs a firm $500 to carry on a yearly business of $10,000, the percentage that must be allowed for this item of expense is 5%.
The amount of profit can be charged on contract work is another important matter. Many contracts are taken at as low a percentage of profit as 5%. To obtain a contract a firm can take it at this low figure, usually without adding any percentage for the expense of conducting business or for extras that may be overlooked in estimating, it is clear that the greater the number of such contracts taken by the firm, the sooner they must go into bankruptcy. As per the author, a profit of 25% on contract work is not great, though on large work a safe profit of a less amount can be satisfactory. Thus, if a firm aspires to conduct a business successfully, in an honest way, it is important that living profits should be secured, and that to secure them no legitimate business expense can be neglected in making estimates of cost.
To estimate work, a complete and reliable form of estimate is required. It is very important to use them, as it is not always possible to remember the scores of items that should enter a plumbing estimate. The low bidder on contract work often forgets to figure on some important item. The use of a correct estimate sheet avoids these troubles. In connection with this subject there is shown an estimate sheet which is very satisfactory. It is a difficult matter to develop an estimate sheet that will satisfy everyone as great differences exist in the methods and materials employed. Hence an estimate sheet that satisfies one part of the country may not fulfill the purpose of some other section. If obtaining a satisfactory published form of estimate is not possible, one arranged to suit individual tastes can be printed at small cost.