It is a simple enough matter to take off quantities from a set of drawings which are full and complete and are accompanied by detail drawings; but, when the drawings only show the locations of the various fixtures, as most plans of the present time do, an entirely different problem is presented.

To carefully estimate large operations when there are no plumbing plans, the only safe way is for the contractor to prepare a complete set for his own use. All he needs to do is to get a set of blue prints from the architect, tack over the floor plans pieces of tracing cloth and draw an outline of the various floors, showing the various partitions, toilet rooms and the location of the various fixtures. With this for a groundwork the various risers and vertical stacks of soil, water, vent and supply pipes should be marked on the several floors, and detail made showing the method of roughing-in the various toilet rooms. In short, he should make as full and complete a set of drawings as the architect would make, although they need not be so good. Having made a set of drawings, the quantities can be taken off in the same manner as when the finished drawings are furnished by the architect.

To the resourceful estimator the incomplete plans are most welcome, as they give him an opportunity to lay out his own work economically without his competitor having the advantage of as economical a layout. It is a case where the best designer should win, but is not so satisfactory or economical a method for the owner.

It is only large, complicated and important operations that need be laid out in full by the estimator. In small work a piece of white chalk and single lines marked on the blue print will enable the skillful estimator to scale the drawings and take off his quantities, while the chalk mark can be erased subsequently so competitors cannot benefit by the laying out of the system. Sometimes a pencil is used for this purpose by an estimator, and all who use the plans after him know on just what runs he figured, and whether or not the design was economical, while those who are incompetent to lay out their own work benefit by the pencil marks left on the drawings.

Every plumber's office should be provided with a draughting board, instruments and materials, and those who wish to follow the business of estimator or become contractors should learn mechanical drawing, so they can lay out their own work on paper. The drawings being for their own use need not be finished productions, so long as they show clearly the work to be performed.

Instead of using tracing cloth and inking in the lines, the experienced estimator can use tracing paper and lay out his work thereon in pencil lines. Even more, he can lay out the work in single lines provided he is going to take off the quantities himself. If, however, one man in an office who is skilled in economical design is to lay out the work and another man take off the quantities from the drawings so prepared, the better plan is to make full and complete working details, then there is no possibility of the assistant going astray in taking off the items. If there is a handy boy in the office, the work of making plumbing plans and details will not be found burdensome, for the boy can do all of the drawing of walls, partitions, toilet rooms and other parts of the building which only require tracing, and all the chief estimator or designer will have to do is to lay in his pipes and make his details.

Sometimes plans which are turned out by an architect's office as full and complete are so complicated that an estimator sees where he can, by redrawing them and laying out the work, according to his own ideas, so simplify them that much money can be saved. When such is the case, he should receive permission from the architect to do so before going ahead with his estimate, for some architects absolutely refuse to permit any changes to be made from their layout, even though the work would be bettered thereby.

When permission is given an estimator to prepare his own layout of the plumbing work, when the architect's layout is unsatisfactory, whether to estimate on the original layout, and rearrange if the contract is secured, or estimate on the new layout, will depend, of course, on whether all the competitors are estimating on the original drawings, or likewise have had permission to arrange to suit themselves.