In the erection of the average house many trades take part. If it is a simple wooden cottage in the country, the local carpenter and handy man is usually competent to do the entire work, with the assistance now and then of a plumber or a mason from a neighboring village. Trade unions, hours of labor, and even the exact compliance with the contract and the drawings count for but little under these circumstances.

In metropolitan districts the situation is much more complicated in that each trade is highly organized and jealous of its prerogatives, specialized labor and machinery are available, and all agreements must be carefully drawn and scrupulously observed.

It is customary to employ one contractor for the general construction, and allow him to select the more important subcontractors for the heating, plumbing, and wiring, and his minor subcontractors for the masonry, roofing, plastering, and painting. Thus the coordination of the work is under one head and yet the responsibility for its completion is ensured both by the general and subcontractors. Owing to the added responsibility for the general contractor, it is customary for him to include as part of his profit, which is distributed through his bid, a commission on the bids of the subcontractors; but where there is competition for the main contract, he will cut his profit to a very small percentage.

If the owner employs the subcontractors directly for a few of the larger items, the responsibility for their cooperation is largely shifted to the architect, and his fee is correspondingly increased, since he is taking over part of the general contractor's work. Often a better choice of mechanics may be made in this way, and there is no danger of the builder "shopping out" the subcontracts to undesirable firms. For small residences this method is not advisable.

A successful combination of these methods may be economically employed in projects of $20,000 or over, by the architect taking separate bids on the heating, plumbing, and electric wiring and then allowing the general contractor to take over these figures as an allowance to be included in his estimate, with the understanding that the firms nominated by the owner shall be employed to execute their parts of the work. This involves no extra fee to the architect, and, if the general contractor submitted his bid in competition, his commission or profit on the subcontractor's work would be reduced to a minimum, as he knows that reputable firms will be employed, and that he cannot pad his own figures if he wants to get the job.