FORM-LUMBER CLASSIFICATION of the MATERIAL-DISTRIBUTION ACCOUNT is obtained the total amount of lumber received for use in forms, and by deducting the amount still piled, a close approximation can be made of the amount used. Then, assuming that the net amount made up into forms is 75 000 ft, boardmeasure, and that Classification (1) on the PAY-ROLL DISTRIBUTION-SHEET shows $1 500, the AVERAGE LABOR-UNIT (1) $1500/75 $20 per 1 000 ft, board-measure. The CURRENT-COST UNIT for the last period can then be found as noted above.

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3. Placing Forms. (See (2) to (5), Labor-Classifications.) The quantities desired for these classifications, square feet of area, etc., are determined by actual job-measurements, or from the drawings by scaling the completed portions of the work. For example, let it be assumed that the forms for four-fifths of the first self-supporting floor of a building have been erected at the termination of the latest cost-period, at which time the entire labor-expenditure for this classification (4)-1, was $1 200. From the drawings or from the actual buildingdimensions, in case the former do not represent the work as constructed, the area of four-fifths of the first floor is found to be 12 500 sq ft. Then, by division, the Average Labor-Unit (4)-1, is $1 200/12 500 $0.096 per sq ft.

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4. Receiving Materials. (See (6) to (9), Labor-Classifications.) The quantities desired for these classifications, thousand feet of lumber, cubic yards of sand, etc., are the amounts of material received, and are taken from the record of job receipts.

5. Reinforcement. (See (10) to (12), Labor-Classifications.) The quantities desired are the weights of steel fabricated and placed, expressed in hundreds of pounds. The first is found for both (10) and (11) by deducting the amount still in the stock piles from the total received. The quantity placed is determined by computation from the steel-lists or from the drawings. The same method used for the other classifications is then applied, except that a considerable amount of detail-work is required in arriving at the WEIGHT OF THE REINFORCEMENT. In order that this weight shall be correct and include the percentages of waste and laps, T irons, etc., which were approximated in the original estimate, the computed amounts should be checked as far as possible, on the invoice-totals.

6. Concrete. (See (13), Labor-Classifications.) By inspection of the job or from the superintendent's report, a record is obtained of the portions of concrete poured. The volume in cubic feet of each item is then computed by the same method as that described for the corresponding elements in the original estimate. (See Chapter XIV, pages 356 to 380.)

7. Stairs, Sills, Mullions, Copings, Curbs, and Ornamentation.

(See (14)

to (19), Labor-Classifications.) These quantities are obtained from the drawings, after inspection of the job or upon information received from the superintendent. It should be remembered that they include no concrete or steel, as each of these is covered by its respective classification.

8. Surface-Finishes. (See (20) to (23), Labor-Classifications.) Having at hand a list of the items completed, the square feet of surface are scaled from the drawings.

9. Cinder Concrete. (See (24), Labor-Classifications.) The cubic feet are computed as in the case of stone or gravel concrete. (See (6), Concrete.) 10. Tile Partitions. (See (25), Labor-Classifications.) The number of square feet of partition-area is determined from the drawings, and on a record of the job-accomplishment.

11. Brick. (See (26) and (27), Labor-Classifications.) By inspection of the job or by report, a record of the wall-areas of different thicknesses is obtained, and the quantities computed from the drawings in thousands of bricks, using the same factors as in the original estimate; and toward the close of the job, or as soon as practical, checking upon the total quantity of brick received on the job.

12. Plastering. (See (28), Labor-Classifications.) The number of square feet of plastered area is determined from the drawings and on a record of job-accomplishment.

13. Ironwork. (See (29), Labor-Classifications.) The quantity desired is the weight of iron installed, expressed in hundreds of pounds. Having at hand a record of the units placed, the weight is computed directly from the invoices.

14. Windows, Trim, and Doors. (See (30) to (32), Labor-Classifications.) The quantities desired for these classifications are determined from the drawings after inspection of the job, or upon information received from the superintendent.

15. Excavation and Pumping. (See (34) and (35), Labor-Classifications.) To obtain the cubic yardage of excavation completed at a certain date, it is necessary to measure the work and even, in some cases, to run a series of crosssections. The proportionate size of this item in relation to the whole job should determine how much work is warranted in getting accurate results.

16. Overhead Expense. (See (36) to (40), Labor-Classifications.) All of these items are computed for cost-analysis purposes as percentages of the TOTAL CONCRETE-COST, and no quantity is required. It is to be noted that certain other items, such as POWER and WATER, appearing in the list of MATERIALCLASSIFICATIONS, require the total concrete yardage, to be used as a quantity in computing the unit cost.

17. Unit Material-Costs. By reference to the invoices and the MATERIALDISTRIBUTION ACCOUNT, the average unit material-costs can be computed for each of the material-classifications. But, although authentic information is thus obtained on the cost of a barrel of cement and a thousand bricks, etc., the actual cost of a cubic foot of concrete or brick masonry cannot yet be computed. The next step is to find the AMOUNTS of material entering into the estimate-units.

18. Material Factors. These amounts can best be expressed as FACTORS. For example, the theoretical CEMENT-FACTOR for a cubic yard of concrete is, for a 124 mix, about 1.50, representing the average number of barrels of cement required for 1 cu yd of concrete measured in place; including grouting, etc., the actual cement-factor may be 1.60 barrels per cu yd. The computation of this factor should be made each time that the concrete-volume

is figured, by dividing the number of yards into the number of barrels of cement used in the concrete-work represented. The object is not only to gain the purely moral satisfaction of knowing that the right amount of cement is going into the job, but also to insure against waste as, in extensive work, with cement costing about $3 a barrel delivered, a very small variation proves extremely costly. For sand and gravel and the other aggregates the FACTOR is not so important during the progress of the work, but should be computed for the entire job at the close of the concrete-operations.

In the case of forms, both making and placing, if it is desired to check the lumber used in the different portions of the work, the only practical method is to take typical sections of the structure and make an actual count of the stock used, allowing for the loss in cutting, etc. The writer has experimented with a number of systems designed to segregate the lumber used in the different classes of work, and has found them all most difficult of application. For standard construction, as detailed in Chapter XVIII, the FACTORS used in making the estimate (see Chapter XIV, page 383) will be found very nearly correct, and it is not considered necessary to include a check upon these amounts in the current reports.

The checking of the actual quantity of steel reinforcement used, against the weight called for on the drawings, is not usually necessary during the progress of the work, except as noted in 5. Reinforcement. After the job is completed, however, any OVERRUN should be proportioned as a percentage of all parts of the structure, except those for which definite schedules were ordered.

For terra-cotta walls and partitions the number of tiles required should be compared to the wall-area laid up, so that the tiles needed for 100 sq ft of surface, including breakage and waste in cutting, can be determined. Furthermore, the MATERIAL-DISTRIBUTION ACCOUNT gives the totals of cement, sand, and lime used for this classification, and these FACTORS can be obtained as soon as the work is completed.

Brick, as in the case of terra-cotta, should be computed, per square foot of walls, for different thicknesses. The object is not to prove the well-known theoretical quantities, but to discover breakage or waste and to check the mortar-ingredients used in the different classes of work.

Plaster is subject to more variation from the theoretical quantities required than almost any other material. This is principally due to carelessness in laying the block, excessive thickness of jambs or grounds, or the use of warped blocks. The quantities of different materials received can be taken from the MATERIAL-DISTRIBUTION ACCOUNT, the unused bags or barrels deducted, and the amounts divided directly by the areas plastered.

It should always be borne in mind that the determination of MATERIALFACTORS during the progress of a job is at best only a close approximation, but after the work is finished it is a comparatively easy matter to get accurate figures if the classifications have been intelligently made. At that time all minor discrepancies between theoretical quantities as computed, and actual amounts of any material used, should be divided into percentages over the different portions of the work, using in each case that particular kind of material.

This, however, should be done with judgment, as noted in the case of steel reinforcement, so as not to increase any item, the actual amount of which is accurately known.

As the UNIT LABOR-COSTS are developed they are entered on the COST-SHEET, as shown below. The UNIT MATERIAL-COSTS are entered only on the out

COME-SHEET, where both labor-units and material-units are compared with the original estimate.

3. ESTIMATE-ANALYSIS

1. Purpose and General Method. In order to make a comparison, item by item, between the original estimate and the actual costs developed on the job, it is necessary to ANALYZE the former into its component parts of labor and material. Furthermore, the easiest way to check the efficiency of the different classes of labor employed upon the various portions of the work, is to reduce the labor allowances for each classification to man-hours and then, by reference to the speed schedule, to determine the size of the gang required to accomplish each item of work at the estimated cost and in the allotted period. With due allowances for foremen's time, and incidental expenses, such information gives the job superintendent a most valuable check upon the conduct of his work.

The PROCESS OF ANALYZING an estimate is substantially that of ESTIMATING REVERSED. For example, in the case of wall forms, a price of 0.22 per square foot of wall-area is used in the estimate, and in order then to compare with our current labor units for making and placing forms, it is necessary to divide this

figure into the different materials and the three labor classifications which it

covers.

In all cases the information is taken from the PRICE-SHEETS of the original and subsequent estimates.

For purposes of illustration, in the following paragraph the data of the estimate in Chapter XIV are used.

2. Forms. From the PRICE-SHEET, page 383, are copied the following

This tabulation gives the component parts of the figure from which the priceunits for CONSTRUCTING the different classes of forms were developed; and it merely remains to sum up all the estimated allowances representing this part of the work (including the waste-allowance but not including erection), and to divide the total in the same proportion as the total $84 was divided in the estimate.

Again, referring to the ESTIMATE SHEETS for the quantities and to the PRICESHEETS, for the prices, the following items are picked out, as representing all the ESTIMATE-ALLOWANCES for making forms.