63U.7 M58r no. 9 cop. 2 Ik i 0 This book has been DIGITIZED and IS availabie ONLINE. UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN AGRICULTURE Digitized by the Internet Archive in 2014 https://archive.org/details/methodsanalysisi9196radc CiRCULATIfiQ copy AGRICULTURE LIBRARY DNIVERSITY OF ILLINOIS BGR/CULTURE LIBRARM REPORT F FROM THE MICHIGAN STATE UNIVERSITY I AGRICULTURAL EXPERIMENT STATION EAST LANSING BUSINESS Methods Analysis in Residential Construction By Byron M. Radcliffe, Aubrey E. Wylie, and Thomas H. Halberg Department of Forest Products INTRODUCTION AND BASIC CONCEPTS Background of Industrial Engineering IN THE CONSTRUCTION of houscs, there are infinite variations possible in the materials used and work methods employed. The differences in practices of builders today reflect their widely varying opinions re- garding the relative effectiveness and efficiency of construction techniques. Some builders are more efficient in their overall operations and within certain segments of work than others. There exist many wide- ly varying circumstances and conditions in the build- ing industry that support these individual opinions and practices, at least in part. However, little has been done to test the opinions in a realistic way. Among construction workers there are great differ- ences in performance, a large part of which is due to methods rather than native ability. It is not appropriate to continue to follow the prac- tice of simply comparing times required for methods used by builders in order to find answers to questions relating to economy in construction. The only logical approach calls for systematic analysis of methods within an organization, leading to the rational selec- tion of alternatives ( of the best methods ) for the con- ditions and circumstances that exist at a given time and place. This is the basic tenet of industrial engi- neering. It has been widely assumed that industrial engineer- ing principles and techniques were not applicable to house construction because of the unique nature of the building process regarding on-site erection. There is no factual basis for such a contention. Some of the techniques of observation, measurement, and analysis which have been refined to a high degree in mass production operations of the metals industries do not suit the problems in building exactly. With, some innovations, however, most of these can be profitably apphed. Systematic analysis of construction methods requires the extensive use of techniques of data collection and analysis. Development of these techniques over many years by industrial engineers has followed the pioneer- ing works of Gilbreth and Taylor in time and motion study, Gantt in work programming, Shewart, Fisher, and others in statistical sampling methods, work sampling studies by Tippett, and others since the turn of the century. The application of industrial engineering principles in many industries has brought about the revolution of efficient mass production and quality control. De- spite the overwhelming evidence of its effectiveness, direct application of industrial engineering in the con- struction field has been negligible until the past two or three years. The most significant effort to date has been project TAMAP (Time and Motion Analysis Project), a joint project of the National Association of Home Builders and the Stanley Tool Works, Inc., undertaken in 1961 through 1962. Working with Robert F. Schmitt in Berea, Ohio, TAMAP proved that very significant cost savings in construction could be made through the application of industrial engineering even to progressive and efficient builders such as Schmitt. The TAMAP engineers showed that techniques could be made to suit the unique problems of each con- struction. They also indicated many areas where further refinements were needed. Some important problems must be worked out. It has become apparent that the average industrial engi- neer is not well enough acquainted with building tech- nology, practices, and the myriad of code and trade restrictions. At present it appears that the building industry is not prepared to take full advantage of the results that can be achieved by industrial engineering applications. Builders must realize the importance of detailed systematic investigations necessary in methods analysis before industrial engineering can be applied properly. Besides the research needed to develop methods analysis for residential construction, there is need for a broad educational program as well among builders. It is necessary that the builder thoroughly understand the function of industrial engineering within his organization. General Scope and Objectives of Project MARC A continuing research project, Methods Analysis in Residential Construction (MARC), was established in the Forest Products Department at Michigan State University two years ago as a part of the research and instructional program in Residential Construction. The major purposes set forth in MARC are: ( 1 ) To study and evaluate the effectiveness of the principles and techniques of industrial engi- neering as applied to work measurement and methods analysis in residential construction. Integration of modular design is an important part of methods analysis. (2) To adapt existing techniques and develop new ones where necessary to those phases of study which are unique to construction. (3) To conduct extensive industrial engineering studies of commonly accepted construction methods and practices in cooperative research projects with builders who have demonstrated particularly efficient construction methods. This research involves formulation and analysis of problem areas, search for and evaluation of alternatives, specification of preferred solu- tions, and the restudy of their effectiveness in application. (4) To accumulate standard time data and develop criteria for comparative analysis of alternative methods. (5) To organize and develop research findings into suitable form for use in courses of instruction within the Residential Construction Curricu- lum at Michigan State University and also publish findings for dissemination to the build- ing industry. Actually, the scope of project MARC could be called work study or methods engineering rather than industrial engineering. The latter term has become very broad and somewhat vague as to subject matter included. A breakdown of the areas of study within project MARC may be outlined as follows: ( 1 ) Methods Analysis (a) Areas of study (1) Product design (2) Work Methods (3) Manufacture ( fabrication, erec- tion, finishing, etc. with comparison of shop vs. field where applicable) (4) Materials handling (b) Typical techniques used (1) Layout diagrams (2) Multiple activity and work pro- gramming charts (3) Flow charts for processes and oper- ations ( 4 ) Detailed construction drawings and specifications (modular coordina- tion) 2 % NOTE: Methods analysis, except for modular design, is not demonstrated in the example house study of this report. More detailed applica- tion of methods engineering is a part of the overall research of MARC to be reported in a subsequent paper. (2) Work measurement (a) Areas of investigation ( 1 ) Stop and continuous watch study (2) Memo-motion (time-lapse photog- raphy ) (3) Micromotion film analysis (4) Work sampling Methods and Techniques Used in a Study of the Framing of a Typical Project House The study of a typical project house of wood frame construction will be used for illustration. The general fundamentals of industrial engineering and modular design used in the analysis are covered here; the description of the house and details of construction are discussed later. Time Measurement Methods Three methods of collecting time data were used in the study of the framing of the project house: con- tinuous watch, memo-motion, and work sampling. Continuous Watch Method. A stop watch with a sweep hand measuring 1/100 minute increments was used for this method of time study. A smaller dial on the face of the watch indicated the elapsed time in minutes. The hour of day was recorded separately by the engineer from a wrist watch. In some industrial engineering work, the snap-back method is used. In this method, the time study analyst stops the watch at the end of an observed element and reads the elapsed time. However, such a technique is generally used in cases where observations are inter- mittent. In a continuous manufacturing process, such as the construction of a house, elements are timed successive- ly. A stop watch is started at the beginning of the work period and runs continuously. The time analyst reads the time at the end of each element observation. The element time can then be found by subtracting from this the end time for the previous element. Notes and time recordings are kept on a data sheet indicating the activity observed, the rate at which the work was accomplished, the termination time, and any additional information necessary in later analysis of data. Thus the time analyst has a rather busy job in the continuous watch method, particularly when elapsed times are short. It is necessary to have every- thing systematized, as will be discussed under the headings of time breakdown and rating below. There is a limit to the refinement of time elements for a continuous watch study. Elements requiring less than 0.10 minutes, which occur in prolonged succes- sion, are difficult to time, rate, and describe accurate- ly. When more detailed information (as in motion economy study) is needed, motion pictures offer a better method of observation. In very detailed study, slow motion may be used. A continuous watch study requires a time study man for every workman involved. The analyst must note every activity of the workman during the work period studied. It is important that the workmen be thoroughly indoctrinated, or considerable misunder- standing and chaos may result. Prior to making a time study, the person in charge should hold a briefing session with the supervisors and foremen involved and completely explain the purposes and procedures of the proposed study. These men in charge of construction may then inform their workmen. This psychological aspect cannot be minimized. The workmen observed must be sympathetic and coopera- tive if the results of the study are to be valid. Also, it is important that the workmen become used to the presence of time study men so tliat they perform in a natural way at their accustomed pace. However, the constant presence of an observer exerts a mild form of supervision on the workers that is probably never eliminated. Memo-Motion — Time-Lapse Photography. A spe- cial motion picture camera device was built for this method of data collection. This apparatus takes a single picture frame every 1/lOOth minute. The elec- tric driving mechanism is accurately timed. The equip- ment is shown in Figure 8. The camera is situated to photograph the entire area under study. Occasionally the vantage point may have to be changed. It is not generally feasible to keep all workers in view at all times and still be close enough to film the detail required for analysis. For instance, workers frequently walked from the house to the lumber pile. So additional notes, keyed to time, are required to supplement data. The resulting film is subsequently viewed in a manually operated device equipped with a frame counter. The number of frames for the completion of a work element corresponds to elapsed time in 1/lOOths minutes. Another application of memo-motion film is in over- all operation or process analysis. By running the film at the usual 16 f.p.s. an accelerated "Keystone Kops" version of the work may be studied. Many pertinent 3 facts can be observed wliich would not be so obvious at regular work rates. Memo-motion has the most important advantage of being a permanent detailed record, particularly on material handling. The film may be re-analyzed with different element breakdowns for any type of subse- quent information desired. In MARC, work is presently in progress to refine memo-motion techniques. Both the usual 16 mm film and 8 mm are being used. One development has been to include a continuous running watch in the field of view. A detailed report on memo-motion techniques wdll be published at a later date. Work Sampling. This technique for analyzing work is based upon the theory of probability. Rather than observe and record all the time required to per- form a job, as in the stop watch method, a relatively large number of observations are taken at random. The method provides information about the relative percentage distribution of work elements rapidly and at far less cost than by the more laborious method. The sample size may be computed mathematically for any arbitrarily acceptable percent of accuracy selected. This applies for the case of a specific ele- ment to be examined. A percentage occurence for the remaining elements will also be found from such a study, but the reliability will vary. The sample size may be found from the equation: A A N = M. a~ Where: N = number of observations; P = estimated percentage occurrence for the element studied; and a = standard deviation of the percentage. The standard deviation of the percentage can be preset to any confidence level desired, usually 95 per- cent. P must be estimated. This can be done on the basis of past records, or a preliminary sampling may be conducted to form a reasonable estimate. Once N has been determined, the sampling time schedule should be made using a table of random numbers to completely randomize the schedule. ^ It should be stressed that properly used, work sampling is an excellent method of determining ele- mental occurrence percentage. But is is also sub- ject to considerable misunderstanding by those not well schooled in the mathematical theory of statistics involved. In subsequent MARC investigations, this method will be used and developed for application to construction. 'For more detail on work sampling theory, WorJc Sampling, (1957), by R. Barnes, published by John Wiley and Sons, New York, is recom- mended. Comparison of Relative Merits Between Continuous Time Studies and the Work Sampling Method. Two methods of continuous time study (continuous watch and memo-motion) were used in this research. Both methods can be used to produce the same data. The motion picture technique has the advantage of being a permanent record for reviewing if a diflFerent set of elements is chosen or for additional information. The continuous watch method does not require the rather expensive memo-motion equipment, but, on the other hand, requires more qualified time study men. Memo-motion is presently being used more extensively in a current MARC project to further evaluate its effectiveness and cost. It is often the case that work sampling could be used instead of either method of continuous time study. A work sampling study can be designed to yield any reasonable degree of reliability by statistical calcula- tion of the proper sample size and a carefully devised random sampling schedule. To use work sampling, the engineer must be well versed in the theory of probability. Several salient advantages and disadvantages of work sampling compared to continuous time study may be itemized as follows: (1) Work sampling is less costly and results may be obtained more quickly. Not only is the number of observers less, but processing the data is far simpler. One time study man can observe several workers in a sampling study. (2) Observations in a work sampling study may be spread over a longer span of time if there is a chance of the work activity being cyclic. (3) Unless rating factors are to be applied, a time study man does not need to be as highly trained as a man on conMnuous watch work. (4) In the time between randomly dispersed observations, the work sampling man can make note of other information. (5) Continuous watch observation is very de- manding of attention and fatiguing. Fatigue can increase human error. A work sampling study can be interrupted if necessary and re- sults will not be affected. (6) Work sampling does not affect the workers psychologically as does the continuous pres- ence of time study men with watch and data sheet. This latter has a significant influence on behavior. (7) Work sampling is not easily applied to work of short cycle duration. Also, in any study, more detailed information and finer break- down is possible by continuous watch study. 4 (8) The results of a work sampling study are diffi- cult to sell to management or labor if they do not understand the basic statistical theory upon which it is based. (9) The most serious danger of work sampling is that the technique can be improperly applied by unqualified people and erroneous results used for hypotheses. Work Breakdown - A breakdown of work, productive and non- productive, into appropriate categories is necessary in order to make any rational evaluation of the effective- ness of an operation or process. Usually the major breakdown in a construction job will be obvious by the trades involved, materials used, function of the part of the structure, and other factors. In this report, such major parts are referred to as work phases. Within phases there will be larger subdivisions which have natural and easily defined limits or boundaries. Thus, in a house, the structural wood floor system would constitute a phase. Placing and nailing sub- floor would be a subphase in this example. The final refinement in work breakdown is called a work element. The information desired determines the elements used. The degree of refinement depends upon the use to be made of the data collected. If, for example, total time spent nailing sheathing was one of the important things to be determined, the element would be simply "nail." If more were to be discovered, this could be subdivided so that time getting nail from apron, positioning, and driving could be found. If elements are too short in duration, then time recording becomes difficult or impossible. An element is the basic unit for observation. Thus it must be clearly defined as to points of beginning and end, so that observing elapsed time will have mini- mum error. The following suggestions for work element break- down have been evolved in project MARC and are quite universal in application to almost any type of construction work. This method recognizes four levels of activity: (1) trade or job, (2) operation performed, (3) work division, and (4) work element. Levels 1 and 2 are dependent upon the type of building, geographic location, and formal restrictions associated with con- struction. Work division and work element are more standard in definition and application. If the pur- pose of an investigation is for a preliminary study, the first two levels are recorded as they are found to be in use. This is the case in this study of a frame house. 2 A proposed work measurement system. Rex P. Huguelet, an un- published report. Dept. of Forest Products, Mich. State University, E. Lansing, Mich., 1963. If, however, improvement is sought, methods engi- neering would be applied first to improve the job or process before a time study is conducted. Organization of the first two levels is determined before a study is made. Trades must be kept separate and operations should also be kept separate. If they are intermixed, they must be recorded at the time data are taken in the field. Work division and work elements are also recorded as the data are being taken. This method, as presented, is intended for the analysis of excellent quality memo-motion film or short duration stop watch study. It will also find appli- cation in work sampling studies. For less than excellent quality memo-motion film or long duration stop watch study a number of elements must be combined to fit within the limitations of the analyst. It appears that the use of four levels of work activity will greatly facilitate locating problem areas in man- power utilization, material handling, etc. This system should also provide a base for standard data when methods have been corrected. Provisions for tools or equipment that are used infrequently have been made by the element "use tool". Work Division Breakdown: 1. Get material 2. Get tools 3. Assemble 4. Plan and inspect 5. Delays 6. Remanufacture 7. Unaccountable Divisions Defined: Get Material — any travel for or with material with distance traveled of four feet or more. Travel of less than four feet is included in the element performed rather than as "Get material." Get Tool — same as "get material" except object is tools or equipment. Assemble — all physical productive and non- productive work not involving material handling of four feet or greater and excluding inspections, delays, and remanufacture time. Disassemble is included in this division. Plan and Inspect — any productive mental action or inspection. Delay — any non-productive non-working time further divided into avoidable and unavoidable delays. Remanufacture — the correction of defective work. 5 Unaccountable — time breakdown cannot be de- termined because of lost watch time or worker outside range of view of camera. Elemental Breakdown: I. Get material 1. travel empty 2A. search 2B, select 2C. fill 3. prepare for use 4. travel loaded 5. pre-position II. Get tools 1. travel empty 2A. search 2B. select 3. maintenance 4. travel loaded 5. pre-position 6. set up 7. use III. Assemble 1. measure and/or mark 2. cut material 3. position 4A. clamp or temporary brace 4B. hold 5. pre-position 6A. nail 6B. drill and bolt or screw 60. place clips 6D. tie steel reinforcing 7. remove waste 8 A. excavate 8B. backfiU SC. grade or level IV. Plan and inspect 1. consult drawings and confer 2A. plan operation 2B. inspection 3. level, plumb, or square V. Delays A. Unavoidable 1. change location 2A. scheduled break 2B. gone from location 3A. idle due to limiting operation per- formed by others 3B. idle, wait for material, tools, or assistance 4. rest to overcome fatigue B. Avoidable 1. walking 2A. unscheduled break or self-induced delay 2B. gone from location VI. Remanufacture 1. remove 2. replace or repair VII. Unaccountable The system outlined permits any degree of refine- ment or, in an opposite sense, combination of activities. For a detailed element breakdown a shorthand giving number and letter designation can be used. In the analysis presented in this paper, the element break- down is detailed. Rating Rating is a technique in which an adjustment factor is applied to an observed time measurement in order to correct it to a corresponding normal time. Normal time is defined as the average length of time required to perform a task by a worker having average ability and adequate experience, working at a rate that can be maintained without undue fatigue. Thus a rating factor is used to level out the variability in productive performance of individual workers doing the same task. Before a rating factor can be applied, it is necessary that the time study man have a valid concept of what constitutes "normal" rate and also that he be able to consistently recognize this normal rate of produc- tivity when observing any qualified workman. This requires training and practice. Further, the observer must be able to judge devi- ation from normal quantitatively so that he may apply a numerical correction factor or rating factor. There is good reason why effort rating is highly controversial. Even assuming a rating system with a clear definition of normal rate and a mathematically defensible means of measuring deviation from the mean, there is still the questionable factor of the analyst's personal judgment. There is no universially accepted method of per- formance rating. However, there are certain con- cepts of "normal" rate of performance that are gener- ally accepted. Walking at a rate of 3 miles per hour and dealing 52 cards into four equal piles in 0.45 minutes are instances of classic rules for average rate of performance. Many companies have their own standards, usually recorded on motion picture film, of normal rate for common activities involved in their plants. Mundle and others have demonstrated that: 6 (a) a concept of normal based on some such criteria is quite readily learned by time study men and (b) a concept of normal using one good "benchmark" can be transferred to another activity without too much difficulty.^ In the MARC research, time study men were familiar with the generally used benchmarks for normal. Since, in the framing studied, nailing and walking were predominate activities, the research workers studied these to agree on a normal rate. For normal rate of performance in this study, the rating factor is 100 percent. The ability of an observer to detect accurately the exact decimal deviation from normal is not as easily attained as is that for recog- nizing normal. Thus, practice of rating motion pictures of activity for which the actual rates have been pre- determined is necessary. It is also a general practice to check periodically the rater's ability with films. There are many factors which cause the rate of any worker to be different from normal. Some involve the individual from both physical and psychological aspects. There are other circumstances such as physical and mental requirements of the task, con- ditions of the work place, and other factors which influence performance and output. Much has been written about the difference between skill acquired by training and that due to natural aptitude. Many students of this subject point out the subtle integration of method as it affects performances. It is understandable, then, why so many rating systems have been developed. The more complex (and perhaps exact) are called "performance" rating systems. An example of this are the "Westinghouse" systems. These more complicated methods are usually referred to as "leveling" since they are applied to a group of observations. Regardless of the detail and complexity of any recognized rating systems, the greatest emphasis is always upon speed or pace. In the simplest system (pace rating), this is the sole criteria. For work of the type presented here, a system must be extremely straightforward and easy to apply quickly (since every observation has a rating factor). Thus, in MARC, pace rating essentially was used. Actually, since the analysts were all very famihar with carpentry work, subconscious qualifications are made based on apparent skill. In order for pace or speed rating to be applied, it must be assumed that every worker is adequately trained and naturally qualified to do the work. This, in a sense, establishes a "normal workman" concept. The rating factor, then, is the analyst's opinion of 'Mundle, M.E. (1960). Motion and Time Study. Prentice-Hall, New York. effort applied productively by any workman at the time of observation. Some industrial engineers express the view that the use of rating should be avoided if possible. If a measure of average, normal, or standard time is to result in such a case, this would mean: (1) only average workers working at a normal pace or (2) a large number of workers doing the same job would be observed. It is assumed that a rating system can be applied to advantage providing the frailties of the system are stressed where "normal" times are presented as re- sults. Modular Design in Lumber Framing Although this study was primarily intended as an example of work measurement, this part of methods analysis is so important it is treated in some detail here. Sound modular design can result in substantial savings without in any way detracting from the struc- tural soundness or the architectural design. There has been a gradual shift toward modular design of both structural and non-structural components. The designer and builder should survey the market for available component parts. General Concept. Modular design is the method of designing a house framework, sheathing, and finish covering to minimize on-site rework of materials and reduce work. This is done by dimensioning the structure to conform to the sizes and shapes of materials, such as lumber and plywood, etc., as they are manufactured. Modular coordination has a secondary connotation which puts responsibility on the manufacturer to manufacture materials to sizes which best fit the needs of the designer and builder. The manufacturer is responsible to some degree for a major module of 4 feet as a result of the decision to produce sheet materials such as plasterboard, plywood, fiber board in this dimension. However, the industrv has been slow to adopt window, door, and other units to modular dimensions. Thus confusion still remains. Modular design must be carried out in three dimen- sions if it is to result in maximum efficiency and cost savings. The present modules were set by exterior wall construction. Most codes require 2x4 studs to be placed 16 inches on center. Thus we have the most common modular system as follows: Major Module = 4'0" Minor Module = 1'4" Sub Module = 4" 7 Where codes will permit 2 foot spacing of studs, we have an alternate system. Major Module = 4'0" . Minor Module =: 2'0" Sub Module = 4" Sometimes it will be advantageous to use the first module system for wall fraxning and floor joist framing and the second for roof framing if trusses are used 2 feet on center. Most designers and builders have found that the exterior dimensions (from outside to outside of rough framing) yield the most economic results. Thus house widths and lengths in multiples of the major module of 4 feet are used. As may be seen, such a method will result in non-modular interior dimensions by mul- tiple of wall thickness. Floor Planning (Wood Joist Floors). It must be as- sumed here that the basement or crawl space has been accurately poured or laid up to an out-to-out multiple of major modules if joists are spaced on centers. This will be the case most generally en- countered. First, there are some general considerations which should be studied. A square house will enclose more area economically than a rectangle. Of course, a square would pose aesthetic problems. However, a 28 or 32 foot width will yield more house per dollar than a 24 foot width. These widths will allow better floor planning for room size and arrangement as well. Since joists run perpendicularly to the longest house dimension and generally rest on a central beam, the outside width can be changed by minor modules of two foot increments. No problem in floor framing or subflooring arises in this case. The effect on the ceiling and roof framing is not costly, especially where trusses and drywall are used. The only cost increase would be in the exterior wall framing, which is more than compensated for. The length of the floor, however, should be confined to out-to-out major modules because the joists will be 16 inches on center, as will the studs, but the trusses will be 2 feet on center. So the common major module makes possible the most compatible use of both 16 inch and 2 foot minor modules in the same system. A grid of 16 inch squares to proper scale should be used as an underlay. The exterior perimeter of the floor is then drawn and joists indicated 16 inches on center. Joists should be butted rather than lapped at the center to provide modular spacing for plywood subfloor. It should be pointed out that recent research shows bridging is unnecessary. The position of the stairwell should be studied so as to minimize disturbance of the modular joist system. The interior walls, plumbing, etc. will be shown on the floor plan. It is well to floor-plan with the same grid underlay so that the floor structure may be upset as little as possible. Where walls must fall over joists or where additional joist doubling is required, this will be more easily seen, and proper decisions may be made as to partition location. It must be strongly emphasized that a good floor plan should not be sac- rificed to save a floor joist, but often a slight, insigni- ficant change can result in a saving. With clear span truss construction, interior wall partitions are non-load bearing which reduces the requirement of the floor joist below. Interior Wall Framing. In the house studied, the 16 inch minor module applied because of local codes. As with the joist floor system, the vertical wall layouts are made with studs 16 inches on center. Generally a double 2x4 top plate is used. In some systems, a continuous lintel of two 2 x 6's on edge around the entire wall may be used and headers for doors and window openings up to 4'6" done away with. The first consideration of interrupting the modular layout is the placement of windows and doors. Many modular pre-built window and door units are avail- able which minimize the problem. If the window or door opening is not modular, an attempt should be made at least to position it so that one side coincides with a modularly placed stud. Cripples are not necessary over windows. If a double 2x6 header ( continuous ) is inadequate, or the double 2x4 plate is used, the header should fit tightly beneath the plate. Then only a 2 x 4 horizontal nailer is needed for window or door units. Corners may be simplified to 3—2 x 4 studs in several ways. If sheet (4' x 8') sheathing of proper thickness is used, diagonal bracing may be eliminated. Roof Framing. In low cost houses, complicated roofs are an unnecessary luxury. A straight rectangle is most' economical. L shapes are not too expensive, but too many ridges, valleys, hips, and dormers run the cost up rapidly. Timber trusses 2 feet on center are recommended. Valleys can be fabricated on site conventionally. Thought must be given in floor planning as to just how things such as chimneys will fit into the truss spacing. Cold air return ducts and plumbing must also be properly located so as not to require moving trusses or adding framing. Overhangs, rake overhangs, etc. can be fabricated on the deck separately or as part of the wall. 8 STUDY OF THE FRAMING OF A TYPICAL LOW-COST PROJECT HOUSE Definition of Study Problem Description of Study House and Limit of Study THE TIME STUDY was conductcd for the rough framing and sheathing stages of construction of a one-story wood-frame house on a basement. As may be seen from the simpHfied floor plan and eleva- tion plans (Figure 1), this was a small (864 square foot area) three-bedroom ranch-style house very typi- cal of low-cost project houses built over the country. Many models of this particular house, with slight modifications, were scheduled for construction in a subdivision by the same builder. Very similar houses had been built in the same area the previous year. Thus there was an ideal situation for reviewing past plans, specifications, schedules, and other information prior to making a detailed time study. Also, since almost identical houses were being constructed in sequence, it was possible to conduct preliminary studies to establish data collection schedules - and details. The rough-framing stages studied were done by a framing subcontractor with well-trained crews of car- penters and a progressive attitude. Relations between the industrial engineering research group and this contractor were excellent. It should be mentioned that, in this case, the subcontractor did not have con- L£FT SIDE ELEVATION FRONT ELEVATION £□ CD m RIGHT SIDE ELEVATION REAR ELEVATION Fig. 1. Floor plan and elevations of the MARC study house. trol of material specification or delivery and handling. This restricted the efi^iciency of his work considerably as will be shown. Also there were restrictions placed on him by FHA, code regulations, local trade prac- tices, and some dictates of the general contractor. However, these things are quite typical of the general procedures in home construction. A first decision was made not to change anything regarding methods, design, or any aspect of the house for the time study. Thus, the study was a completely objective scrutiny of the process as it existed. In an ordinary application of time and methods study, changes in methods, processes, design, and equip- ment would be suggested after preliminary analysis. Rough-in construction included the lumber framing of the floor, exterior walls, interior partitions, and roof. The sheathing of the exterior walls, nailing of board subfloor, and nailing in of roof plywood sheathing were included. In this house, the rough-in included setting the steel beam for the floor, installing windows and door jambs, and building the cornice on the ex- terior at the roof and wall juncture. Work commenced after the basement walls had been completed and back-filled to rough grade. The lumber, plywood, and sheathing were delivered in a single steel strapped package, but not precut in any way. Roof trusses, with metal plate fasteners, and gable end frames were delivered prefabricated to the site. These were stacked loose. The nail-on aluminum windows and door jambs were placed on site separate- ly as were miscellaneous materials such as sill sealer, nails, and metal hangers. All material placement was done at the sole discretion of the suppliers' truck drivers. As well, the arrangement of material in the bound package was not specified by the framing contractor. Before framing commenced, the steel I-beam was set on the foundation and supported by three steel posts in the basement. However, this was included as a part of floor construction. This contractor used a precutting table and saw setup shown in Figure 5. The setup was placed as advantageously as possible between the lumber pile and the house basement. As much precutting of lum- ber as possible was done on site with this jig table setup. Other than electric hand saws, all fabrication work was manual, including material handling. A power drop for electricity for the saws was made from a pole every two or three lots. This house was of conventional wood frame con- struction except for the roof trusses. The design was typical of most code and FHA specifications. Wood joists were spaced 16 inches on center, lapped at the 9 center over the steel I-beam, and nailed to solid boxing (or bond) around the perimeter. One devia- tion from most situations was that the joists and bond rested directly on the concrete wall rather than a wood plate. The usual requirements for headers and double joisting at walls were followed. Diagonal wood bridging and blocking was installed. The subfloor was of diagonal 1x6 boards which were hand nailed with 8d common nails. Site pre- assembled landings and stairs were positioned after the flooring. The exterior walls were 2x4 construction with studs spaced 16 inches on center, and a double 2x4 plate around the top and a single 2x4 sill plate. Window and door openings were spanned with head- ers and cripples as is common in this type of con- struction. Rack braces of let-in 1x6 boards were used in the exterior walls. One-half inch fiber board sheathing was hand nailed with galvanized sheathing nails in accordance with FHA nail spacing specifications. The four exterior walls were framed and sheathed horizontally on the subfloor and then tipped up in place, plumbed, and nailed at the base and corners. Windows were tacked on and portions of the eave cornice were pre-built and secured to the walls before tilt-up. Interior partitions were of similar 2x4 stud con- struction but not dry-walled or sheathed. Roof trusses were carried and positioned one at a time. They were plumbed, laced, and secured. Ply- wood roof sheathing was hand nailed with 6d nails after being carried, lifted, and positioned by hand. The final rake cornice was installed. Briefly, this was the scope of framing work to be studied by time measurement. A few steps are shown in Figures 2 to 7. Preliminary Study for Work Measurement The principal means of work measurement for this study was by stop watch. Considerable use was made of time-lapse motion picture photography to evaluate merits of these two techniques. A work sampling study was also conducted. Regardless of the method used in a time study, certain preliminary work must be done in order to plan the measurement work. The type of work done must be thoroughly understood so that proper work elements can be defined for observation. The se- quence of work, crew size, worker movement about the job, and other such facts must be established. As mentioned, previous plans, specifications, and schedules were available from past work. The ana- Fig. 2. Typical site for study house ready lor floor framing. lysts were familiar with carpentry work in general and the conventionally accepted type of construction described above. For this framing job, the contractor used three separate crews, one each day for three days. The first day, after several men from nearby crews helped set the I-beam, a two man crew con- structed the floor system and laid the subfloor. One of these men did all of the precutting for this and other stages at the jig table and cutoff saw and helped the second man on floor framing when needed. The second crew of three men came on the second day and worked on the exterior walls. One of these worked a portion of his time on the cutoff saw. A final three man crew worked the third day on interior partitions and the trussed roof construction. Thus the work of rough-in framing seemed to be clearly divided into four major divisions, referred to here as phases; namely, floor, exterior walls, interior partitions, and roof. Fig. 3. Package of lumber and sheathing for a typical MARC study house. 10 Some overlapping of crew activity within phases occurred. For instance, the saw man of the first crew precut material for all phases. Thus exactly what he was cutting had to be carefully noted so that the time could be properly allocated. Several other such in- stances occurred. Also, in operations such as tipping up walls, men from nearby houses would help for brief periods. When a worker left the site, then, his activity and whereabouts were carefully noted. A valuable aid in summarizing work by time of day, phase, and activity is the multiple activity chart. This information can also be used in further analysis to investigate required crew size, relative efficiency of crews, amount of direct supervision, effectiveness of mechanization, etc. The type of multiple activity chart used in this study is illustrated below. This is an actual portion of the chart for the last half of the first day of framing. One time analyst was used to compile a multiple activity chart for a typical house. As was mentioned before, several houses of the same type were under construction continuously so it was possible to follow one through completely. The time study man made entries of sufficiently explanatory notes keyed to the time of day and the individual workman. During this preliminary study, the engineer also MULTIPLE ACTIVITY CHART FOR PROJECT MARC STUDY HOUSE TIME No. MAN 1 No. MAN 2 11:30 — 12:30 — 1:30 — 2:30 — 3:30 — install bridging and blocking saw int. studs saw stair treads install joist hangers position, tack and saw 1x6 subfloor install blocking position and tack subfloor assemble landing frames install basement window sofBt nail deck hang landing hang landings and install basement window soffit nail deck columns clean up clean up r Fig. 4. Manner in which pre-assembled trusses were delivered to site. made complete notes concerning tools used, tech- niques and skills necessary, methods, and other perti- nent information. After all of the preliminary observations and studies were completed it was possible to make a chrono- logical breakdown of the job into work phases and subphases as follows: I. Floor System 1. Set steel I-beams and basement posts 2. Place sill sealer around foundation 3. Construct the beam, joist, and header framework 4. Install joist spacer blocks at beam 5. Floor joist bridging 6. Position subfloor sheathing (includes some hand nailing to tack) 7. Nail subfloor 8. Install soffits above basement windows 9. Basement stairs 10. Drop landings at exterior doors II. Exterior Wall Framing Rough-In 1. Layout from plans 2. Frame (sills, plates, studs, headers, and cripples) 3. Install let-in 1x6 diagonal bracing 4. Sheath 5. Cornice construction 6. Install aluminum "plant-on" windows 7. Door jambs 8. Tip up walls and secure III. Interior Partitions Rough-In 1. Layout from plans 2. Frame 3. Erect, plumb, and brace 4. Install ceiling backing where needed 11 IV. Roof 1. Erect prefab trusses 2. Plumb, aline, and lace trusses 3. Aline cornices 4. Sheath roof deck In subsequent analysis, it was desired to determine the work content (man minutes) devoted to each phase and subphase so that a study for improvement could be made. For this reason, time must be divided into more fundamental and meaningful pieces associated with work elements. Definition of work elements was also necessary for data collection so that a length of time could be associated with a definite occurrence whether productive or not. A detailed analysis was made of all types of work and activity for all workers throughout the phases Fig. 6. Time study analyst recording data for a sub- assembly. Fig. 5. On-site precutting setup. and subphases. As described in Part I, a limited num- ber of work elements can be defined which will com- pletely describe all work. Several cardinal rules were applied in listing work elements as follows: (a) The degree of refinement of elements was determined by the use to be made of these arbitrary divisions in analysis. Smaller elements can always be combined if need be, whereas subsequent division of large element observations is possible only when data are on motion picture film, (b) Elements should not be smaller than necessary because this introduces unnecessary addi- tional work in observation. In fact, where a stop watch is used, very short elements (less than 0.10 minute) are difficult to record accurately, particularly when a succession of like elements takes place, (c) An element must be clearly discernible as to exact start and finish points, (d) Elements clued to use of certain tools or materials or specific body movements are easy to observe. For the rather broad type of analysis in this study, eleven work elements were sufficient. These were described as follows: (1) Pfon — reading plans, instruction or consulta- tion, inspection. ( 2 ) Get Tool — travel to and from location of tool, select or put away, perform adjustment or maintenance, power hookup. (3) Get Material — travel, selection and carry ma- terial, or take scrap away. (4) Change Location — continue same operation but change position or place to continue ( such as walk across floor in nailing subfloor). (5) Position Material — place material or subas- sembly in final position before securing in place. ( 6 ) Measure — measure and mark with rule, tape, or square for size to cut, layout, nailing line, etc. Fig. 7. Workmen framing exterior walls of study liouse on the subfloor. 12 (7) Cut Material — select, position on table, and cut for table saw or saw with hand, power, or manual saw. (8) Nail (9) Delay — any loss of time waiting for material, labor, help, instruction, or personal indecision. Any delay but rest. (10) Res? — personal delay to relieve fatigue (pur- pose clear). (11) Rework — any activity to correct mistakes. This element noted with explanation as to what was being done. The basis of effort ratings applied by the Analysts in this study was described earlier in the general discussion of rating. Time Studies — Data Collection Continuous Watch Study A time analyst was assigned to every workman to follow his activities continuously for the entire time he was on the job. One study man was unassign- ed and free to observe overall activity. This man was responsible for taking 35 mm slides of pertinent pro- cesses, material handling, and so forth. He also made supplementary notes on observations relative to the operation. When additional workers from other crews were used for tip-up operations, this man noted their time spent on the study house. All time study men were thoroughly familiar with the job from the preliminary study data and informa- tion. Also, all had been instructed on the system of effort rating to be used. At the start of each half day, at 7:00 a.m. and 11:30 a.m., all watches were synchronized so that all notes would be properly time oriented. The watches ran continuously, and readings were taken in hours, min- utes, and hundredths of minutes. A special form of data sheet was developed for this type of field operation, and a standard clipboard was modified with center rings for use in recording obser- vations. It was found that usual paper data sheets were not adapted to the windy conditions. Those used were printed on a heavy manila paper. The usual clip was also found unwieldy under outdoor conditions and was replaced with a loose-ring arrange- ment. It might be pointed out that pencils should be used in case of rain. A sample portion of a data sheet is shown below. Pertinent information relative to the time period span is recorded in the upper portion. Only the first data sheet for each phase was thus headed. The upper portion is self-explanatory. The body of the data sheet has columns for neces- sary time data. Usually a shorthand notation is devel- oped by the analyst which makes possible the record- ing of information needed even when elements are of short duration. Under "element" a code number or letter notation is used. When further information is deemed necessary, this may be noted under "descrip- tion". TIME DATA— PROJECT MARC Page 4 of 23 Observer Radcliffe Date July 9 Study Start...7 A.M Finish 11 :30 A.M. Operator Smith (No. 2) Trade Carp Operation Frame Floor Tools Hammer, Power Saw Material Lumber REMARKS....Notes Start End Coffee Break 9:02.15 Element Description R T RTG NOR End Coffee Break 2-2-15 P 2 X 8's 40 25 110 GM 2 X 8's (select) 80 40 115 GM Walk 3-21 41 115 CP Walk Empty 26 05 110 GM 2 X 8's 92 66 115 P 2 X 8's 4-10 18 115 The column "R" is for watch reading. At the end of each observation, the time in hundredths of a min- ute is recorded. Sometime during the element occur- rence, the estimated rating factor is placed under column "RTG". Subsequent subtractions of readings yield element times and these are recorded under time. These times are in 1/lOOths of a minute. As will be pointed out later, the normal times (under column "NOR") are derived by multiplying "T" x "RTG" = "NOR". 13 Memo-Motion Time-lapse photography with 16 mm film was used for certain parts of this study to check the accuracy of stop watch data and to discover the problems in- volved when using memo-motion under field con- struction conditions. Proper placement of the camera was difficult be- cause of the rather wide area of activity. Even with a wide angle lens, it was necessary to change positions occasionally. Another difficulty in this technique was finding proper vantage points so that an oblique view resulted. The best solution was to mount the camera and equipment on the back of a pickup truck. Fig. 8. Automatic time-lapse camera setup. The memo drive mechanism was set for 100 frames per minute. It was found necessary to have a photo- grapher in constant attendance at the equipment to change exposure settings, viewing direction, and so forth. The reflex camera was found very suitable for constant check of the field of view. Time cards and title cards were photographed intermittently as this information was needed. The analyst assigned to the memo-motion equip- ment was also responsible for taking such supplement- ary notes as necessary. He noted rating factors from time to time for the workmen in view. This then was an average "level" factor. Color film was used entirely. It was found from previous work that identification of men and analysis in general was greatly enhanced using color film. In some later observations, patches of colored cloth were pinned to workers' shirts to make identification easier. An additional camera was used for intermittent close-ups of particular functions or processes for more detailed information. These motion pictures were also 16 mm color at 16 frames per second. Work Sampling A more complete work sampling study such as de- scribed in Part I was not applied in this study. Rather, a rough sampling was done with 200 obser- vation periods per work day for all three days. Each man was observed during the observation period. The times for observation were random. It was the pur- pose of the work sampling merely to be a check on the time study by watch. More detailed work sampling studies were con- ducted on other projects, but the results do not apply here. A relative comparison between watch and sampling studies is given in Part I. Results and Discussion of Time Study of House Framing It should be stressed at the outset of this discussion that the following analysis is for the purpose of illus- tration of how an industrial engineering study may be used to evaluate a job. The data are limited to the specific case studied. Although, as has been pointed out, this construction was quite typical of many build- ing operations; no definite conclusions may be drawn which can be universally applied. In fact, a methods and time study analysis should be applied only within a company, and results should be interpreted in light of current and internal considera- tions. Also, industrial engineering is a continuing function, and no study should be considered final since conditions and economics of manufacture are always in a state of flux. Processing Data It was the purpose of the time measurement study to determine the distribution of man hours between the work phases and also to break this down into sub- phase work content. The elements previously defined were selected in light of how the results were to be examined. Thus, it was to be determined just how time was expended, productively and non-productive- ly, so that some hypotheses for improvement of the processes and operations could be made. Thus for the data from continuous watch, memo- motion, and work sampling, the times observed were accumulated by element designation and grouped into phases and subphases for organization into tables and bar charts. The principal work measurement technique used was the stop watch method. A complete detailed set of data was taken for the entire framing process. Every observation of elapsed time was identified as to element, phase, and subphase and, further, was 14 given a rating factor. The first step was to "normalize" all observed times as follows: Normal Time = Observed Time x Rating Factor All time data were gathered and summarized in the tables that follow. It will be noted that the tables present normal man minute quantities and also per- centages. The latter are often more appropriate for specific comparison. The sequences of memo-motion film were analyzed, frame by frame, in a viewer-counter. Since each frame constitutes 0.01 minutes of elapsed time, essentially the same information was found as that in the stop watch study. In fact, more detailed breakdown would be possible if so desired. This is one decided ad- vantage of memo-motion. From notes taken to accompany the memo-motion, a more general application of rating adjustment was made. Only periodic "average level" rating factors were noted. It was the primary purpose of this research to inves- tigate the feasibility of memo-motion (practically and economically) and to compare the results with those from stop watch data. The results, not given here, were found to be in extremely close agreement with stop watch results. EXISTING FRONT WALL FRAMING MODULAR FRONT WALL FRAMING EXISTING REAR WALL FRAMING MODULAR REAR WALL FRAMING Fig. 9. Examples of modular redesign applied to front and rear exterior walls of MARC study house. Variations between the two methods were in the order of 1 to 2 percent. A much more detailed application of memo-motion is being currently applied in MARC research in pro- gress, and these findings will be published at a later date. The preliminary type of work sampling applied to the entire framing sequence, but the number of obser- vations was somewhat less than would theoretically be calculated for more reliable accuracy. However, the results, as will be shown, were extremely good. Work sampling results are always in percentage of occur- rence and represent observed time since no rating fac- tor was applied. Presentation of the Data Except for the bar chart comparing the results of stop watch and work sampling methods, all data pre- sented below are from the stop watch time observa- tions corrected to normal. Table la to 4b (pages 19-21) give the work break- down by elements within phases and sub phases. All tables designated (a) contain time quantities in normal man minutes. Tables denoted by (b) show correspond- ing percentage breakdowns within subphases (hori- zontal lines adding up to 100 percent for total sub- phase time). At the lower right hand corner for all tables (a) the total time is given as both the sum of element totals and totals in subphases— or the total time in the phase. Added to this is the time for "prepare to work". This time was kept separately because of the manner in which it occurs at the start and end of each work day. The sum total for each phase contains its proportionate part of "prepare to work". The breakdown of the time for the precutting oper- ation on the special jig table is presented by minutes in Table 5a and by percentages within groups of similar materials in Table 5b. This time also is appropriately included in the previous tables accord- ing to where the precut material was used. Since the precutting is a very distinct operation in itself, it was important to analyze the time breakdown specifically. Bar charts are very useful to present results graphi- cally. The overall major results are so presented in Figures 10 to 12. For Figures 10 and 11 the charts are in terms of man minutes. This was purposely done so that relative comparisons were possible between charts. In the case of Figure 12, percent of occurrence is used as the ordinate since this is the only value which can be drawn directly from the results of the work sampling data. Conclusions About the House When a thorough and systematic methods and time study of a construction job is made, man)- factors come 15 into sharp focus which are generally completely over- looked in the casual type of surveillance builders generally keep on their operations. Only in this exact manner can the relative productivity of activity be quantitatively analyzed. In their first brush with an industrial engineer's viewpoint of their operation, most builders are upset to find how much waste time can be attributed to such things as inadequacies in design and planning, supervision, materials handling, tools, and methods which they believed to be quite good. Usually many changes can be suggested prior to a complete time study from the findings of a meth- ods analysis. The time study that follows can then test the effectiveness of the alternative suggested and lead to further refinements in more economical use of men, machines, materials, and minutes. ill il J .Li EMTEHIOH WALLS Fig. 11. Time distribution among phases of rough-in work by subphases. WORK PHASES Fig. 10. Time breakdown of total rough-in construc- tion by work phases. In order to suggest an alternative, the industrial engineer must know in detail the present process or operation in question. He must be thoroughly familiar with the latest tools, methods, materials, etc. which could be applied in a substitution. Mechanization is not always an economical step forward without inves- tigating overhead costs. Almost any change in a pro- cess will have secondary influences on other facets of the manufacture. These must be foreseen. Construc- tion work is particularly restricted by codes, craft skills, union restrictions, and buyer prejudices. Many practical and beneficial technical changes often create far more serious problems than they save in this re- gard. Changes should be gradual enough so as to "phase in" to the production and not cause chaos. Often ma- terial, tools, jigs, or other existing items must be used up or disposed of in as profitable a way as possible. These and many other considerations must be borne in mind. The actual analysis of the status quo should be objective and critical. But a proposal to make a change should be carefully weighed in light of all possible ramifications. The following rather broad conclusions are drawn from this study: (1) The working drawings for this house were inadequate. Most of the framing detail was left to the imagination of the layout man. The fram- ing was not modular, and resulted in waste from scrap or redundant members. 1 - ^ STOP WATCH ~D SAMPLING WORK ELEMENTS Fig. 12. Comparison of results from work sampling and stop watch. 16 Outdated construction practices, such as using bridging in the floor system, resulted in signifi- cant waste in material and labor. Some quanti- tative measure of this may be found in the tables and bar charts. A considerable reduction in time would be realized by using plywood for subfloor instead of 1 X 6 boards. This would increase material costs so that the time savings would have to offset this. If a thicker fiberboard sheathing were used, the let-in rack bracing could be omitted. The material handling problem on this house needs much study. A few suggestions should be tried and checked out. (a) The large single material package was usually not placed near enough to the house. (b) Material in the package was not stacked in order used. (c) Material for the cutoff saw should be packaged separately and delivered to the saw table vicinity. (d) The aluminum frame windows were deliv- ered loose and were quite often damaged on site. Windows should have protective packaging. (e) Trusses were placed too far from the house. (f) In a subdivision operation such as this, the use of a lift fork truck should be investi- gated for material handling during con- struction. (g) Although the jig for precutting on site appeared to be quite efficient, the com- parative cost of such standard items as precut studs delivered should be investi- gated. (h) Cost-in-place of drop landings should be thoroughly checked to see if these actually result in a savings. (i) The obvious labor cost of the cornice in a house of this price class does not appear justified. (j) There appeared to be no reason for chang- ing the crew after phase II. The same crew could do the partitions and roof. (k) Many of the methods used were excellent. The exterior wall tip-up construction was well executed. There was very little re-do work on the job. (1) The delay time was very low. Also the average performance rate was high. The men appeared well trained and qualified. The above mentioned problem areas were the more obvious ones in this study. From a comprehensive study of the data, presented in the graphs and tables, many other items would suggest more detailed study. As an example of this, it was noted that a large amount of time was spent nailing subfloor, wall, and roof sheathing. Use of a pneumatic stapler might prove more economical. It should be stressed that, once any change is made, a subsequent time study must be conducted to evalu- ate the effectiveness of the change. Modular Design The plans used for this house were completely lacking as to any joist, wall stud, roof truss, or other framing layout. This is, unfortunately, the general case for house construction. In order to study the effect of modular control, it was necessary first to determine the arrangement and spacing of framing members by actual measurement of an existing house. It was found that the layout man had attempted to keep to a 16 inch submodule; but the placement of doors, windows, and interior partitions, as indicated in his working drawings, prevented optimum modular control. A new set of detailed framing layout drawings was made. Windows, doors, and partitions were moved slightly to fall into modular spacing. No changes were significant enough to change the function of the floor plan or upset the apearance of the elevations. The comparisons of existing and proposed framing are shown in Figure 9. The saving in redundant lumber is evident. CONCLUSIONS AND RECOMMENDATIONS General Observations MANY iNDUSTRi.\L engineers in metal working industries, where methods and time study are widely applied, have pointed out that analysts must be very familiar with the processes they observe. This also applies to construction. The time study man need not be a skilled construction worker; however, he must be able to recognize skill and familiaritity with tools and materials demonstrated by the workman observed in order to rate his effort, or judge the effectiveness of a tool or operation. On the other hand, a builder would not be qualified to apply techniques of industrial engineering without 17 adequate training. Some misuse of so-called industrial engineering in construction by untrained people was noted. In order to apply alternate methods suggested by a time and methods study, it must be known whether or not a method change would be acceptable. Often an industrial engineer will be aware of a change which needs to be made to optimize a process or operation. However, there may be code, trade union, or other restrictions which preclude the change. Introducing a new tool or material could cross trade jurisdiction rules. An obviously needed mechanical innovation could violate a union contract. On the subject of mechanization, a careful study should be made to ascertain whether the piece of equipment will be kept busy enough to pay its way. Often a single piece of equipment can serve many functions so its cost can be amortized and an economic advantage realized by its use. New materials and especially "prefabricated" prod- ucts must be carefully studied from an in-place cost. A component, such as a ready hung door, may appear expensive as an item of purchase, but the savings in installation may possibly be a more important con- sideration. However, only an actual cost breakdown study in detail, using both alternatives, will produce the facts. This constant questioning and attention to detailed examination in a systematic study is the basis of industrial engineering. Very few builders have accurate cost-in-place data which are reliable and standard enough to applv from one job to the next. Most estimating is done from past records of similar jobs, but generally the breakdown is too coarse. The knowledge and judgment of a good estimator is not to be under-rated. But such people are far too rare and their "art" is not easily taught. A far better approach to estimating construction costs should be based on well established standards of time, material cost, and overhead. The divisions must be relatively small and well defined. Thus one product of continued industrial engi- neering studies in construction should be such standard data. With enough valid information, syn- thetic time and cost predictions are possible. As has been pointed out before, a good and simple effort rating system is necesary in most time studies. The modified pace rating used in the analysis of the house in this study was satisfactory for the purpose. More work is needed along these lines, however. Every company should set its own standards, develop training techniques, and constantly examine the re- liability of the system used. Major Problem Areas of Home Building Companies The following list of problem areas applies not only to the builder observed in this study, but quite gener- ally throughout the industry. Industrial engineering is critically needed in resi- dential and light construction. In the past two or three years many building companies have become interested. Where methods and time studies have been applied, the following major areas needing work have been evident: (1) A building company should have a clear-cut organizational structure. A published organi- zation chart and set of operating procedures should be made available to all employees. Lines of authority and response should be defined. (2) Direct supervision at the production level is necessary. A constant check of the effective- ness of the foremen should be made to insure proper scope of authority (i.e., crew size). The duties of a foreman should be reviewed. Often such men are burdened with too many actual working functions. (3) Poor material handling practices result in significant unncessary cost. A building com- pany should constantly study this problem in light of alternatives possible within the scope of the operation. Where mechanization is contemplated, a thorough study of overhead cost must be made. (4) Modular coordination in design must be stressed. Use of component parts should al- ways be investigated. However, the degree of prefabrication is a singular economic con- sideration for every company. (5) Scheduling of men and materials is needed. (6) Some continuing industrial engineering func- tion should be maintained. Qualified person- nel should be retained in a staff function in this regard. 18 APPENDIX TABLES TABLE la — Work breakdown (normal man minutes) for Phase I-Deck by subphases and elements Subpbase Plan Meas- Get Posi- Get Cut NaU Change Delay Rest Re- Total in ure material tion tool material location work subphases I-beams and columns . . 2.10 7.52 12.85 34.33 4.22 1.33 1.31 6.89 1.95 1.80 1.20 75.50 Sill seal 0 0 0.52 6.65 0 0 0 0.91 0 0 0 8.08 6.25 27.77 56.34 34.39 7.23 7.62 94.83 7.22 11.00 10.73 0 263.38 0.18 0.29 3.06 3.17 0.64 14.79 0 0 0 0 0 22.13 0.53 5.89 16.15 10.20 2.23 25.83 52.01 0.59 0.70 0.23 4.82 119.18 1.94 0.38 33.30 39.22 7.38 29.78 64.58 1.57 17.32 0.26 1.13 196.86 0 0 4.62 0 0 0 116.47 0 0 0.80 0 121.89 0 4.42 1.17 0 1.69 10.01 2.66 1.20 2.30 0.70 0 24.15 1.65 1.87 9.06 24.48 2.62 13.38 13.10 3.78 0 0.80 3.64 74.38 0.30 2.11 3.92 19.25 1.23 23.03 21.92 1.36 0.25 0 0.32 73.69 12.95 50.25 140.99 171.69 27.24 125.77 366.88 23.52 33.52 15.32 11.11 979.24 Prepare to Work 23 . 27 Total 1,002.51 TABLE lb — Percentage time breakdown for Phase I — Deck within subphases Subpbase Plan Meas- Get Posi- Get Cut NaU Change Delay Rest Rework ure material tion tool material location 2.8 10.0 17.0 45.4 5.6 1.8 1.7 9.1 2.6 2.4 1.6 Sill seal 0 0 6.4 82.3 0 0 0 11.3 0 0 0 2.4 10.5 21.4 13.0 2.8 2.9 36.0 2.7 4.2 4.1 0 0.8 1.3 13.8 14.3 2.9 66.8 0 0 0 0 0 0.4 4.9 13.6 8.6 1.9 21.7 43.6 0.5 0.6 0.2 4.0 1.0 0.2 16.9 19.9 3.7 15.1 32.8 0.8 8.8 0.1 0.6 0 0 3.8 0 0 0 95.6 0 0 0.7 0 0 13.3 4.8 0 7.0 41.4 11.0 5.0 9.5 2.8 0 2.2 2.5 12.2 32.9 3.5 18.0 17.6 5.1 0 1.1 5.0 0.4 2.9 5.3 26.1 1.7 31.3 29.7 1.8 0.3 0 0.4 TABLE 2a — Work breakdown (normal man minutes) for Phase II — Exterior walls by subphases and elements Subpbase Plan Meas- Get Posi- Get Cut NaU Change Delay Rest Re- Total in ure material tion tool material location work subphases 4.79 27.69 1.72 3.81 2.43 3.70 1.48 1.72 0 0,23 0 47.57 2.10 5.28 69.04 61.90 17.05 126.19 156.22 4.41 40.73 13.46 1.12 497.50 0.15 11.00 5.97 6.38 7.62 43.47 11.24 0.60 0.80 1,43 0.77 89.43 6.27 13.86 38.20 29.17 6.56 40.00 164.06 1,70 35.50 8.20 8.82 352.34 10.31 17.60 33.17 59.98 37.24 36.69 91.54 4.89 8.09 9,02 12.96 321.49 2.07 0 7.15 13.67 0.32 3.04 11.65 2,97 0.96 0,11 0 41.94 3.73 6.56 4.21 16.23 4.12 8.19 7.98 0 0 12.82 3.01 66.85 0.58 0 1.38 34.61 1.35 0 37.91 1.08 0,63 1.26 0 78.80 30.00 81.99 160.84 225,75 76.69 261.28 482.08 17.37 86.71 46.53 26.68 1,495.92 Prepare to Work 19.12 Total 1,515.04 19 TABLE 2b — Percentage time breakdown for Phase II — Exterior walls within subphases Subphase Plan Meas- Get Posi- Get Cut Nail Change Delay Rest Rework ure material tion tool material location 10. 1 52.8 3.6 8.0 5.1 7.8 3.1 3.6 0 0.5 0 0.4 I.l 13.9 12.4 3.4 25.4 31.4 0.9 8.2 2.7 0.2 0.2 12.3 6.7 7.1 8.5 48.6 12.6 0.7 0.9 1.6 0.9 1.8 3.9 10.8 8.3 1.9 11.4 46.6 0.5 10.1 2.3 2.5 3.2 5.5 10.3 18.7 11.6 11.4 28.5 1.5 2.5 2.8 4.0 4.9 0 17.0 32.6 0.8 7.2 27.8 7.1 2.3 0.3 0 5.6 9.8 6.2 24.3 6.2 12.3 11.9 0 0 19.2 4.5 0.7 0 1.8 43.9 1.7 0 48.1 1.4 0.8 1.6 0 TABLE 3a — Work breakdown (normal man minutes) for Phase III — Interior partitions by subphases and elements Subphase Plan Meas- Get Posi- Get Cut Nail Change Delay Rest Re- Total in ure material tion tool material location work subphases 4.55 28.80 5.79 1.76 1.42 7.12 1.16 0 0 1.15 .0 49.75 11.39 44.02 74.49 70.59 12.67 82.01 159.92 10.90 8.33 15.48 10.32 500.02 7.39 9.16 8.94 58.14 6.55 0.65 14.32 4.00 0.75 1.45 2.93 114.26 1.23 1.21 6.56 2.33 7.63 2.10 9.70 1.51 1.85 1.66 0 35.78 24.56 81.19 95.78 132.82 28.27 91.88 185.00 16.41 10.93 19.74 13.25 699.83 Prepare to Work 15.18 Total 715.01 TABLE 3b — Percentage time breakdown for Phase III — Interior partitions within subphases Subphase Plan Meas- ure Get material Posi- tion Get tool Cut material NaU Change location Delay Rest Rework 9.1 53.9 11.6 3.5 2.9 14.3 2.3 0 0 2.3 0 2.3 8.8 14.9 14.1 2.5 16.4 32.0 2.2 1.7 3.1 2.1 6.5 8.0 7.8 50.9 5.7 0.6 12.5 3.5 0.7 1.3 2.6 3.4 3.4 18.3 6.5 21.3 5.9 27.1 4.2 5.2 4.6 0 20 TABLE 4a — Work breakdown (normal man minutes) for Phase IV — Roof by subphases and elements Subphase Plan Meas- Get Posi- Get Cut Nail Change Delay Rest Re- Total in ure material tion tool material location work subphases 0.55 1.06 32.09 19.66 2.42 1.38 9.16 3.24 7.62 0 0 78.67 Plumb, aline, brace .... 7.81 17.54 7.78 33.45 1.72 1.38 18.79 22.00 10.84 0 0.32 130.49 0.30 3.02 8.08 13.94 3.08 1.07 5.07 12.36 7.86 0 0 55.63 13.82 14.81 54.82 50.37 18.38 16.33 110.71 11.22 12.71 0 3.60 315.59 22.48 36.43 102.77 117.42 25.60 20.16 143.73 48.82 39.03 0 3.92 580.38 Prepare to Work 15,18 Total 595.56 TABLE 4b — Percentage time breakdown for Phase IV — Roof within subphases Subphase Plan Meas- Get Posi- Get Cut Nail Change Delay Rest Rework ure material tion tool material location 0.7 1.3 40.8 25.0 3.1 1.8 11.6 4.1 9.7 1.9 0 6.0 13.4 6.0 25.6 1.3 1.1 14.4 16.9 8.3 6.8 0.2 0.5 5.4 14.5 25.1 5.5 1.9 9.1 22.2 14.1 1.5 0 4.4 4.7 17.4 16.0 5.8 5.2 35.1 3.6 4.0 2.8 1.1 TABLE 5a — Time distribution (normal man minutes) of work for On-Site Precutting Operation — All phases of rough construction Description item Plan Meas- Get Posi- Get Cut Nail Change Delay Rest Re- Total by ure material tion tool material location work subphases 0 0.72 0.25 1.70 0.98 7.22 0 0.20 0 0 0.29 11.36 0 1.43 2.95 0.69 0.19 15.92 0.29 0 0 0 0 21.47 2.25 1.58 2.96 0.84 4.17 4.49 0 0 4.69 0 0.13 21.11 Headers and cripples . . 3.60 6.45 18.20 6.56 8.47 27.58 0 0.15 0 0 0.15 71.16 Exterior wall studs. . . . 0 1.43 12.10 0 2.08 20.39 0 0.32 0.20 0.18 0 36.70 0.20 3.11 18.45 0 3.05 28.26 0 0 0 0 0 53.07 2.05 1.18 1.76 0 0.64 1.79 0 0 4.45 O.ll 0 11.98 Totals by Elements 8.10 15.90 56.67 9.79 19.58 105.65 0 0.67 9.34 0.29 0.57 226.85 21 TABLE 5b — Percentage time breakdown for On-Site Precutting Operation for item produced Description item Plan Meas- Get Posi- Get Cut Nail Change Delay Rest Rework ure material tion tool material location 0 6.3 2.2 15.0 8.6 63.5 0 1.8 0 0 2.5 0 6.7 13.7 3.2 0.9 74.1 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John Wiley & Sons, New York. Stocker, Harry E. (1951). Materials Handling. 2nd Ed. Prentice-Hall, New York. 23 This publication is part of a new series called Research Reports. The publications are aimed at audiences such as Farmers, home owners, industry people, etc. They will be designated by subgroupings under the following audience classifications: (1) Farm Science, (2) Home and Family Living, (3) Business, (4) Natural Resources, (5) Development and Public Affairs and (6) Recreation and Tourism. UNIVERSITY OF ILLINOIS-URBANA 630.7M5eR C002 RESEARCH REPORT EAST LANSING 9 1964 3 0112 019634317