steam or plumbing risers and floor arches of steel frame buildings, or between plaster ceilings and cement or marble floors, resort must be had to local custom, and the adaptability of the tradesmen involved to that procedure which would seem the most economical in time and money. Other things being about equal, that method resulting in the least total time expended on the structure should always receive the decision.

4. The date on which all field work should be completed; a delay here may or may not be so vital, dependent on whether succeeding trades are held up thereby in the completion of their work.

A slow or faltering trade is always a detriment to any building enterprise, and it is for the quick detection and prompt cure of such symptoms that the time schedule serves its most important purpose.

16. Stages of Building Operations.-The facility and practicability with which a time schedule may be prepared is dependent quite largely on the experience and general knowledge of trade sequences possessed by the compiler. For an initial try-out it is well to conceive the building as divided into the three periods or stages of construction into which it quite naturally groups itself. They are as follows:

(1) Foundations and walls to grade.

(2) Superstructure without finishing trades.

(3) Finishing trades.

First Stage. For the first stage, conditions will be found to vary so with each different structure that set rules do not readily apply. Preparation of site, with possibly a wrecking operation, excavation, foundations, sheet piling, shoring, piling, caissons, steel grillage, and walls to grade may all be involved. In ascribing time values to this class of operations, only an intimate knowledge and study of local conditions can be relied upon. Each individual operation should be analyzed separately, and that starting date established which will result in the greatest harmony to the whole. It should be borne in mind that at this stage the working space is greatly restricted, and the surrounding conditions for the receipt and storage of materials are apt to be at the worst. In order to compensate for unforeseen contingencies, as much slack as the total time allowed for the building will permit should be allotted to this stage of the operation; even at the expense of a sensible tightening up on the schedule for the balance of the work. A rough-and-ready check found useful by the writer is an allowance of 2 ft. per week, the figured distance being the depth to which the footings project below grade. Such a check is not accurate on very deep foundations, such as are met with in Chicago practice with caissons extending 90 or 100 ft. below grade, but more directly applies to rock work and foundations of medium depth as found in the East and elsewhere.

Second Stage.-The second stage, that of the superstructure, is controlled in time values by the three basic trades involved:

1. The supporting steel skeleton, or, if wall bearing construction, the exterior walls themselves. 2. The arches or floor construction.

3. Dividing walls or interior partitions.

All other roughing trades are collateral with or dependent upon one or the other of the aforementioned principal lines.

In the further discussion of the time schedule and its preparation, reference will be had to the steel frame or strictly fireproof type of building as generally found embodied in the modern hotel or office structure. Being more complex in the number and variety of trades involved, it will serve as the best illustration. Schedules for other types of construction can be evolved by similar methods, simply eliminating those trades which do not pertain. On this type of construction 4 to 5 days per story of height is the usual time allowance for erection of the steel frame. It is to be noted that on the above basis the area of the building bears no direct function to the progress desired. It has an effect, however, on the type of equipment to be chosen, which will be referred to later. As an illustration, a 12-story hotel or office building would be allotted from 48 to 60 days in which to carry the steel work from grade to completion, which includes the time required by the steel erector in getting his forces and equipment away from the building. The collateral trades dependent on the steel work should be started concurrently with it or at intervals of a few days-due caution as to the safety of the workmen involved, and the proper sequence to prevent the covering up of uncompleted work by other trades being observed.

The second controlling trade embraces the floor construction, or arches. A safe rule is to set this down to start from 25 to 40 days after the start of the steel; and the third controlling trade, or interior partitions, the same period after the start of the floor arches. In each instance the dependent trades will be assigned their places in manner similar to that described for those following the steel.

Third Stage. For the finishing trades, or third stage of the building, conservative practice permits an allotment of from 90 to 120 days after completion of steel, indicating about 40 days after completion of interior partitions. 1c. Total Time Involved.-Reverting again to a 12-story structure, and assuming that the foundations extend 20 ft. below grade with basement included, the time schedule will now have reached somewhat the following values:

1d. Specimen Time Schedule.-A specimen time schedule as completed and used in actual practice is shown on p. 805. The dates shown in the two right-hand columns are those worked out first by methods just described; those in left-hand columns, the purpose of which has already been referred to, are then deduced from the starting dates. The accuracy with which they may be established depends almost wholly on the exact knowledge possessed by the compiler of modern shop practice, and, to a lesser degree, on his acquaintance with the local customs prevailing in the locality at which the different branches of the work are being fabricated.

le. Time Schedule as a Plan of Operation.-The time schedule after completion should be freely circulated among all interested departments. To the designing engineer or architect, it indicates the precise sequence and the latest date at which all information including approvals must be available; to the contract department it indicates the latest dates on which subcontracts may be safely let; and it also supplies the starting and completion dates to be incorporated therein. It furnishes the purchasing department with exact information on which to base future deliveries of stock materials; to the expediting and traffic departments it is indispensable in following up the preparation, shipment, and delivery of fabricated materials from distant shops and factories; to the building superintendent it should be his daily guide and reference for the coordinating of all field activities.

2. The Working Estimate.-Second only to the time schedule as a controlling feature is the "working estimate." Some authorities will be found who give it preference on certain operations, believing that where time is not specifically mentioned as the essence of the contract, and strict economy only the end to be gained, that a time schedule implying speed will have excessive costs attached thereto. A little thought, however, will dispel such a theory when it is recognized that a properly prepared time schedule does not make for speed at the expense of economy, but rather holds its strength through its requirement for orderliness-in itself one of the fundamentals of economics. Through its harmonizing influence, many a valuable day will be retrieved to the owner to become a revenue producer, and at a lesser cost to the operation as a whole than if the work was carried on without its beneficial guidance.

2a. Basis of Working Estimate.-The working estimate may be based upon data already secured through preliminary cost estimates of the work, but is more generally the result of a careful re-check on all quantities, taken direct from the plans after the award of a contract.

For those lines of work on which the builder's own forces will be employed, the quantities of material or labor involved will be set down in conventional terms against which the selected price units will be applied and the whole extended into dollars and cents. This is carried out trade by trade, the greatest amount of detail being observed to insure to the fullest extent the elimination of all possible errors, and holding those that might occur to the minimum value.

If it is deemed desirable to have a complete schedule equalling the total allowance for the building operation, there will be added to the above figures the various sub-allowances for those lines of work which are to be purchased in their entirety, commonly called subletting.

26. Standard Manual For Cost Data.-In order to standardize the work and insure a more accurate and systematic collection of the cost data by field material and time clerks, it has become common practice for the builder to prepare a standard or manual, covering all possible subdivisions of work on which costs will be required, each branch and subdivision of same being indicated by a code letter or combination of letters and figures. The characters of this abbreviated index are then used to indicate disposition on all team tickets or other material receipts as well as subdivisions of time on daily time books, payrolls, etc.

The working estimate can be of value only to the extent of the intelligence with which it is utilized. To check same against actual results obtained on an operation after the work in question has been installed and completed can be productive of no value except possibly in relation to future work of similar character. To secure the full possibilities, some comprehensive system of cost recording is essential; data as to progress made, materials used, time involved, etc., should be collected daily by the field clerical forces with the results tabulated in weekly or semi-weekly reports. Where the volume of work in any particular line is large and fairly constant in its character, weekly reports will probably fulfill every requirement, but where the volume is small or the conditions under which it is proceeding are constantly changing, the semi-weekly or even daily reports should be prepared. The comparison of these reports with the working estimate and the interpretation of the disclosures therefrom by the

building superintendent, or whoever may be making the comparison, can be beneficial only to the extent of his thorough understanding of the factors with which he is dealing. He should never fail to realize that the working estimate treats of averages only and that to draw a true comparison, the particular parcel of work under scrutiny if greatly at variance from the average, should be modified correspondingly by proper allowances before judgment is rendered.

A type of estimate more logical in its application, and at the same time slightly less difficult in preparation, is one in which the allowances are expressed in hours of labor rather than in terms of value. It recognizes the theory that the rate of wages applying to any particular locality is generally on a more or less established basis and beyond the province of the organization to change or alter. By limiting the unit of measure to the expected output per hour or day of laborer or mechanic, the field organization forces may be held accountable only for those factors over which they have admitted control. Another advantage lies in the far greater readiness with which such terms are accepted and made use of by foremen and other employees. An allowance of 80 brick per hour on a certain piece of masonry would be understood by all and is easily checked against by the simple operation of dividing the number of brick laid during any selected period by the number of mason hours employed; whereas the same allowance expressed in terms of $12 per thousand, is to the average individual quite a complex problem to check against except to those who have had previous estimating or cost-preparing experience.

3. Daily Reports and Diaries.—A third instrument essential to every building operation, but of lesser importance as a controlling feature, is the daily report or diary. This is prepared in the field and written up for each and every day, Sundays and holidays included. Each report should be numbered consecutively from start to finish of the operation so that the latest number will always indicate the duration of the job in days up to that point. Outside of certain essentials such as weather conditions prevailing, the total number of employees, classified by trades, mention of any unusual mishap or accident, and the visitation of important personages -the scope of the diary may be varied by the responsible head to suit the particular work engaged upon. The best results will be obtained if these reports are personally prepared by the superintendent in charge, the assurance being thus gained that he is actually in touch at all times with every feature and detail of the operation. If, due to the scope of the work, this is found to be impracticable, he at least should sign the reports and see that they are transmitted to the main or home office at the end of each day.

PREPARATION OF SITE

BY A. G. MOULTON

It can be assumed that certain essential information, locating the proposed structure both horizontally and vertically with relation to known references, will be clearly indicated on the plans and sections previously prepared by the designing engineer. Horizontal distances given in feet and inches between opposing lot or building lines, the angles formed at their intersection and the elevation of the first floor with reference to existing grade or some assumed datum comprise the information commonly given. In addition to this, the structure as a whole will generally be tied up by a figured dimension or dimensions to some established line or point. This may be an adjoining building, a party line, a street intersection or simply a stake or hub, should the site be an isolated one.

4. Location of Reference Points.-The first step by the field engineer should be to locate the reference points, consulting with such municipal departments as may be interested to inform himself as to the system of local grades, and any existing ordinances that would call for formal permits, such as street obstructions, vault excavations, sidewalks, etc. Offset stakes or batter boards will be established for all corners or changes in direction of the building lines, care being exercised to so locate them that they will not be readily disturbed during the excavation period. One or more bench marks will be set up at convenient points against which all future building levels will be checked. The careful engineer will find time to re-check at frequent intervals all batter boards and benches until foundation operations have reached a point where there is no further danger of ground movement or other disturbance, and he will in particular make a re-check of all lines and corners before permitting any masonry work of foundations to proceed.

If the foundations are to project to some depth below the street or normal ground level, or in moving ground or apt to be of a hazardous nature, he will establish a series of benches on one or more piers of each of the adjacent buildings; also on all surrounding street curbs, street crowns, car tracks, or other points in the immediate vicinity that might be disturbed during the foundation construction. This disturbance or settlement may be expected through caving banks, yielding of street piling, borrowing of ground water or running sand. Freedom against same can best be assured by tight sheeting, properly braced and carried well in advance at all times of the excavation. Having established the aforementioned benches, periodic reading on same will be taken and a careful record of the results preserved. Unless startling conditions manifest themselves through cracks in the walls or pavements, weekly readings will probably be sufficient until such time as foundations have reached grade level, after which they may be discontinued. If the new structure is to be annexed to an existing building, with communication thereto at one or more levels, the engineer will take check readings on all floors of the old buildings to detect any departure of same from the assumed levels. If the information is not otherwise available, it will be well at this time to cross-section the site as then found, for the purpose of checking excavation quantities later on.

5. Photographs.-An extremely valuable supplement to the engineer's records can be obtained through the medium of photographs taken of the site before building operations are started. Such photographs should be identified by name, number and date scratched on the negative, or, better still, by a transparent label pasted thereon. A series of such photos taken at weekly or 10-day intervals throughout the entire construction period form an extremely instructive and invaluable record of the operations. If possible, photos should be taken from the same viewpoints so as to better illustrate the progress during succeeding intervals.

6. Removal of Pipes, Wires, etc.-Service pipes, hydrants, lamp posts, mail boxes, poles, and wires which encroach on the site should be noted, identified for ownership, and the owners notified to remove or properly protect same.

7. Wrecking. Before wrecking existing buildings, suitable precaution should be taken for protecting the public traffic and pedestrians. The size and location of the operation will determine the method to be adopted. A tight fence, 6 ft. high, at the curb line, turning the sidewalk traffic on to temporary walk laid in the gutter, may be sufficient. In more populated districts, and where the operation is to be of some length, it may be required to erect a shelter shed over the sidewalk, permitting the public to retain the use of same. Building ordinances of most municipalities cover this point and they should be consulted to provide against possible violations. If sidewalk vaults are to be incorporated in the new building, the walk way can be elevated above the normal grade a sufficient distance to facilitate the passing of materials beneath and into the lot as excavation proceeds. By erecting the shelter in this manner, it can in many instances be retained to serve throughout the entire construction of the new building. The supporting sills will be carried on temporary wooden bents until retaining or street walls are up and permanent sidewalk beams are in place.

The wrecking of frame structures presents no features requiring special preparations. Brick, steel, and concrete, however, cannot be successfully handled without a well studied program and more or less of an equipment plant, depending on the type of structure, ground area, and height. If more than three stories, brick and rubbish chutes will be found to be indispensable. Their erection should be such as to make easy delivery to wagons or trucks at the lower end. Except in cases of shallow buildings, the chutes should be located near the center of the building, thus equalizing the wheeling or handling on the working floor above. Temporary planked driveways may be provided for bringing the trucks or wagons to the bottom of the chutes.

7a. Disposal of Waste.-Driveways should be laid out so traffic is continuous in one direction. To accomplish this, enlarged openings may have to be provided through external walls of the ground story with consequent shoring, but the effort will be worth while, for speed on a wrecking operation is almost wholly dependent on ability to promptly move the resulting material and rubbish away from the site. Rubbish chutes are commonly built of 2 or 21⁄2-in. plank, 30 to 36 in. square, erected vertically, in story lengths, with the splices directly above the successive floor lines. No bin is required and control at outlet is secured through a floating false bottom, full area of the chute, attached to long wooden lever. Brick chutes are composed of open troughs 30 in. wide and with 12-in. sides set at an angle of 45 deg. but reversed through each story to provide a zigzag path in the usual method.

76. General Equipment for Wrecking. For lowering steel members, pipe, and other heavy pieces of equipment that may be encountered, a pole or light derrick may be found necessary on the working floor. Materials are lowered through a court-way, if one is available,