Masonry Magazine May 2001 Page. 10
FIELD FACTORS AND
PRODUCTIVITY LOS
IN MASONRY WORK
Jeff Buczkiewicz, MCAA Director of Marketing, Calin Popescu, PhD., PE, and Nuntapong Ovararin
Many research studies have proven that productivity loss is a result of several causes including excessive change orders, long periods of overtime, poor field management and severe weather [1, 4, 8, 9]. In fact, these factors typically generate several additional field factors or disruptions affecting masonry productivity that are beyond the direct control of a mason contractor, and result in productivity loss or additional man-hours required to perform the masonry work. Unfortunately, estimators have difficulty in quantifying the impact of productivity loss, and current construction contracts do not usually include sufficient language to identify compensation for masonry productivity loss due to field factors. In addition, in a construction claim, the period of normal productivity without an impact of field factors, and the detailed cost accounting records generally are not available for determination of the additional costs [2]. The quantitative evaluation of productivity loss due to field factors in masonry construction is therefore needed.
A recent research study conducted by the consortium of MCAA and the University of Texas at Austin has proposed a quantitative evaluation of productivity loss due to field factors based on a national survey. The objective of this study is to quantify productivity loss caused by field factors based on standard field conditions. More than 850 questionnaires were randomly distributed to mason contractors, and 152 questionnaires were collected in the year 2000. mason contractors can employ the results of this survey to determine additional man-hours needed to perform the masonry work in field conditions that differ from original expectations. Moreover, if field factors are present, the contractors can determine an increase in the required masonry labor. This study will produce a more defined and accurate estimate to improve construction estimating, planning and scheduling, and construction claims. This study will also enable general contractors to be aware of field condition levels that might produce significant loss in masonry productivity.
DEFINITIONS AND SCOPE
This research study has defined masonry productivity as a measure of input (man-hours) per unit of output (area of masonry work). Productivity loss is then described as the lost man-hours per unit of area of masonry work, and the percentage of productivity loss (%PL) is the expected percentage of lost man-hours per unit of area of masonry work. This study has focused on field factors that significantly affect masonry productivity in building construction that are beyond the direct control of a mason contractor. These field factors can result from various circumstances involving excessive change orders, long periods of overtime, poor field management, negative surrounding work activities, and extreme weather and environment.
SURVEY RESULTS
According to the study analysis, Figure 1 presents the average, minimum, and maximum percentage of productivity loss due to field conditions based on standard field conditions shown in Figure 2. A total of 16 field factors were explored [5], with each factor given 3 standard field conditions: minor, moderate and severe conditions. There is an assumption that the expected percentage of productivity loss of any factor is derived from the effect of that specific factor with no effects of other factors involved. This study is intended to serve as a reference only, and the factor descriptions may not contain the comprehensive details involved. The results provided may be too high or too low for some mason contractors. Therefore, the results should be modified accordingly based on the individual contractor, the crew, and the job.
Field factors beyond the control of the masonry contractor, such as congestion, can initate productivity loss resulting in an increase in required man-hours.
HOW TO USE THE SURVEY RESULTS IN PRACTICE
The study results provided in Figure 1 shows %PL, which can be utilized and modified to better estimate the required man-hours needed to perform certain work in field conditions that differ from original expectations. The estimators can also determine the increase in the required masonry man-hours, if field factors that are beyond the control of the mason contractor are present. The following samples are presented to propose a better understanding of how to apply the results, and a cumulative approach is adopted to determine additional man-hours due to field factors. Sample 1 below shows that if the expected number of man-hours lost due to anticipated field factors 1 and 3 is 250 hours, then the total estimated man-hours required to perform the masonry work is 1,250 hours. Sample 2 shows that the total lost man-hours is 500 hours (from C) including 2 components: 1) 300 hours of lost man-hours due to the differing field conditions that are beyond the control of