summary of the PAY-ROLL DISTRIBUTION (shown on page 463), which must total to the complete pay-roll for that period.

COSTS.

4. Material-Classifications. For the purpose of obtaining UNIT MATERIALCOSTS, all materials are divided into certain classifications. Under these headings in a MATERIAL DISTRIBUTION ACCOUNT are entered the quantities and prices of the different items, from which information are developed the UNIT MATERIALThis procedure is necessary to provide a means for obtaining the AVERAGE COST of materials rather than the quotation upon any chance invoice. It also determines a correct distribution to their proper classification of all the minor INCIDENTAL MATERIALS, which often total to large expenditures. By this method all transportation-charges, demurrage, etc., are entered with the materials to which they apply; and, in general, all expenses incurred in connection with any material of any certain class is charged to that classification. If this principle is constantly borne in mind, and the COST OF MATERIAL considered to cover all expense up to the POINT OF DELIVERY UPON THE JOB, there will be no question or doubt as to the proper classification. In this connection it should be noted that the item TRUCKING, when appearing in the pay-roll, must be transferred to the MATERIAL-ACCOUNT and entered under the material involved. It should also be noted that when any item, such as Delivery, is included in a subcontract, it is omitted from the MATERIALCLASSIFICATIONS and entered under the appropriate heading in the subcontract

account.

5. List of Material-Classifications.

(1) Form-Lumber. All lumber and other materials used in constructing forms. This includes moldings, coves, wedges, etc. Also, under a separate subdivision, nails, bolts, oil, and grease are to be included.

Unit: One thousand feet, board-measure (M. ft B.M.) of form lumber.

(2) Cement. All cement, including transportation to the job and the return transportation of empty bags, and the testing of cement.

Unit: Barrel of cement.

Note. The bag-credits are entered in this account and deducted from the gross cost to give the net cost of cement. The account should be arranged to show the BAG-LOSS, which is a valuable check on efficiency in the handling of bags. White cement, non-staining cement, etc., are entered under Special Materials, Classification (20). At the close of the job all cement included in this account and not used for concrete-work is deducted and proportioned under the classifications of work for which it was used, such as brickwork, etc., by use of the daily construction reports and MATERIAL FACTORS developed for those items. (3) Sand. All sand, including transportation. Unit: Cubic yard.

Note. Deductions for the amount used in work other than concrete are made, as in the case of cement. White sand is entered under Special Materials,

Classification (20).

(4) Stone (Crushed). All crushed stone, including transporation. Unit: Cubic yard.

Note. Deductions for the amount used in work other than concrete-work are made as in the case of cement.

(5) Gravel or Mixture. All gravel, or mixed sand and gravel including transportation.

Unit: Cubic yard.

Note. Deductions for the amount used in work other than concrete-work are made as in the case of cement.

(6) Reinforcement. All materials and their transportation including tools used in fabricating or placing the reinforcement, except power-machines, which are classed under Plant, Classification (18).

Unit: One hundred pounds.

(7) Cinders. All cinders, including transportation. Unit: Cubic yard.

Note. Deductions for the amount used in work other than cinder concretework are made as in the case of cement.

(8) Terra-Cotta. All terra-cotta, including partitions, furring, flue-lining, coping, etc. Include, also, ingredients of mortar and strips of tar paper, if used between courses. Subdivisions are made for different classes of work. Unit: Square foot of block, linear foot of flue-lining or coping.

(9) Brick. All materials used in brickwork, including the ingredients of the mortar, acid for washing down, horses, scaffolds, etc. Subdivisions are made for face-brick and common brick.

Unit: One thousand bricks (M. of brick).

(10) Plaster. All materials used in plastering, including horses, mortarboxes, scaffolds, etc. Subdivisions are made for Portland-cement plaster, patent plasters, and lime plaster.

Unit: One hundred pounds.

(11) Light Iron. All frames (except for windows), sills, guards, lintels, rails, or other light ironwork. Subdivisions are made for structural sections, piperails, and safety-treads.

Unit: One hundred pounds.

Note. Cast-iron bases, sleeves for columns, beam-rod-separators, etc., are entered under Classification (6).

(12) Metal Windows. Windows, frames, sashes, glass, hardware, putty, etc., and metal trim when used. The materials used in grouting metal sash are also included.

Unit: Square foot of masonry-opening.

(13) Interior and Exterior Trim. All finish-millwork, except for doors and wooden windows. Subdivisions are made when the importance of this item justifies its further analysis.

Unit: Linear foot of members.

(14) Fire-Doors. All fire-doors, including trim and hardware of all kinds. Unit: Square foot of opening.

(15) Wooden Doors. All wooden doors, including rough backs, jambs, thresholds, trim, and hardware of all kinds.

Unit: Square foot of opening.

(16) Excavation. All materials used in work of excavation, such as lumber for runs, barriers, etc.

Unit: Cubic yard of excavation, measured in place.

(17) Power. All cost of electric current, supplies for and repairs to motors. In the case of steam-driven equipment, include coal, engine-oil, etc.; likewise gasoline or kerosene, when used for power.

Unit: Reduction to a cost per cubic yard of concrete placed.

(18) Plant. Rental-charges for mixers, engines, hoists, towers, concreteconveyances, or other material-conveyances, power-saws, etc., with full operating-equipment.

Unit: Reduction to a cost per cubic yard of concrete placed.

(19) Water. All cost of metered water or the laying of temporary lines; likewise water-barrels, valves, hose, etc.

Unit: Reduction to a cost per cubic yard of concrete placed.

Note. Pipe-lines and fittings used for the heating of materials or for other purposes in connection with cold-weather operations, are classified under (23).

(20) Special Materials. This classification is used to include such materials as are only occasionally used, and for which carefully analyzed costs are unnecessary, such as white cement, white sand, etc. If, however, upon any particular job it is desired to segregate such items, an extra number should be added rather than any subdivisions of the standard classifications.

Unit depends upon type of work.

(21) Pointing and Cleaning. All materials used in pointing or correcting defective work, cleaning up, removing rubbish, etc.

Unit: Reduction to a percentage of the TOTAL CONCRETE-COST.

Note. This classification usually includes trucking-charges, transferred from the pay-rolls.

(22) General Expense. This classification includes all incidental items usually encountered in a typical job, such as permits, traveling-expenses for steady-pay men, postage, stationery, etc.

Unit: Reduction to a percentage of the TOTAL CONCRETE-COST.

(23) Cold-Weather-Protection. All materials used in protection and heating, such as steam-pipe coils, salamanders, canvas covers, coke consumed, etc. Unit: Reduction to a percentage of the TOTAL CONCRETE-COST.

(24) Office-Expense. The cost of shop drawings, purchasing materials, accounting, and the other items of the contractor's overhead charges.

Unit: Reduction to a percentage of the TOTAL CONCRETE-COST.

Note. The items of this classification should be determined by including all office-expense which, either through individual practice or contract-agreement, can be considered as cOST OF THE WORK.

(25) Telephone. Cost of telephone service chargeable against the job. Unit: Reduction to a percentage of the TOTAL CONCRETE-COST.

(26) Tools and Supplies. All small tools, not included under Plant, and miscellaneous supplies, such as shovels, drills, bolt-cutters, hickeys, concreterammers, etc.

Unit: Reduction to a percentage of the TOTAL CONCRETE-COST.

(27) Installation. All cost of lumber and other supplies used in housing the plant, building temporary offices, cement-sheds, tool-houses, etc. Also, trucking of the plant, to and from the job, is included.

Unit: Reduction to a percentage of the TOTAL CONCRETE-COST.

Note.

The chief reason for separating this item from the plant-charges, as given under Classification (18), is that the latter are often limited by contractconsiderations. (See Chapter XV, page 404.)

(28) Accident and Fire Insurance. These two classes of insurance should be divided, and each computed as a percentage of the TOTAL CONCRETE-COST. 6. Supplementary Material-Classifications. As in the case of the distribution of labor, it is usually necessary to add additional classification-numbers to meet the requirements of any particular job. This is done as outlined in Supplementary Labor-Classifications, including an extra classification for materials used on EXTRA-WORK-REPORTS chargeable to the owner, and the full list is forwarded to the material-clerk at the start of operations. The MATERIALDISTRIBUTION-ACCOUNT, based on these classifications, should be kept on the job and promptly posted as soon as materials are received and checked.

2. COMPUTING UNIT COSTS

1. General Procedure.

Having at hand the timekeeper's DISTRIBUTION OF LABOR for a given period and the MATERIAL-DISTRIBUTION, with average

prices worked out for all materials received to that date, the next step is to determine the QUANTITIES OF WORK accomplished during the periods covered by the corresponding labor-expenditures, and, when practicable, the AMOUNTS OF MATERIALS used.

After the job is completed it is a comparatively easy matter to compute the quantities from the drawings representing the work as constructed; but while the operations are still in progress it requires great care to obtain accurate quantities from which to develop the CURRENT UNITS. As an aid in this work the cost-accountant should be supplied with copies of the QUANTITY AND PRICE SHEETS for both the original estimate and subsequent estimates of EXTRA WORK, but those should be used only as a guide, and each element of the work should be again computed. Although the JOB-PROGRESS can be reported by the superintendent, it is much more satisfactory to have the cost-accountant personally visit the work on the last day of each cost-period, as a great deal of information is needed to supplement the drawings.

As it is valuable, in order to check the efficiency of the job, to develop both the average labor-units to date and the labor-units for the last, biweekly, period, it is necessary to obtain both these sets of quantities. This is done by computing the total quantities completed, which are used in determining the average units, and then deducting therefrom the quantities of all periods except the last. For example, let it be assumed that (13), Concrete, in the List of Labor-Classifications, on the present PAY-ROLL DISTRIBUTION SUMMARY-SHEET, shows an expenditure of $800, and that the total expenditure based upon this classification, prior to this last period, was $2 000, which represented the labor-cost of mixing, transporting, and depositing 1 000 cu yd of concrete, and gave a labor-unit of $2 000/1 000 = $2 per cu yd. Upon inspection of the job it is found that the total concrete placed at the termination of the present report is 1 425 cu yd. The AVERAGE LABOR-COST is then ($2 000 + $800)/1 425 = $1.96 per cu yd, and the CURRENT LABOR-COST, for the last period, is 800/(1 425- 1 000) = $1.88 per cu yd. It should be noted that in general ALL QUANTITIES, WHETHER COMPUTED FROM THE DRAWINGS OR FROM THE ACTUAL CONSTRUCTION, MUST BE EXPRESSED IN THE SAME UNITS AS THOSE USED IN MAKING THE

ESTIMATE; and these are the units given under their respective headings in the lists of LABOR-CLASSIFICATIONS and MATERIAL-CLASSIFICATIONS. However, for the sake of convenience the concrete-volume is often expressed in cubic yards.

The determination of quantities for the purpose of obtaining UNIT-COSTS, although in principle extremely simple, usually entails, under job-conditions, a considerable amount of careful, painstaking work. As this is, after all, the only really difficult part, provided the labor and material have been properly classified, the following paragraphs are devoted to a detailed analysis of procedure. The subdivisions, numbers in parentheses, in the following paragraphs, refer to the List of Labor-Classifications.

2. Making Forms. (See (1), Labor-Classifications.) The quantity desired is the actual number of feet, board-measure, of the lumber made up into forms at the termination of the period covered by the latest cost-report. From the