EMPIRICAL DETERMINATION OF LABOUR OUTPUT FORFLOOR SCREED AND TILE FINISHES FOR CONSTRUCTIONWORK IN ABUJA

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

The source of labour output used for estimation of construction cost has been a point of discourse and contention. This is because this involves the quantitative estimation of the labour rates while market survey research for materials prices are the basis for the material cost estimation (Ashworth, 2002). The high degree of inaccuracy found in BOQ estimates is mostly attributed to the uncertainty of the accuracy of the labour constants used in pricing labour costs. Ajia (2002) concluded that while most of the outputs used by estimators are the British originated constants, some contractors adopt outputs gotten from their experience and hence non-uniform outputs are widely in use.

The common method of generating cost estimates for construction projects involves the multiplication of unit rate by the measured quantities in the bill of quantities (Ashworth, 2002). The unit rate is a component of labour rate (obtain from the multiplication of labour constant by all-in rate) plus cost of material and percentage allowance for profit and overhead, while the measured quantities are obtained from drawings and specifications for the works rules specified by Building and Engineering Standard Methods of Measurement (BESMM). The inconsistency in application of a defined output constant for construction estimates has posed a serious challenge to the accuracy of estimates computed by quantity surveyors.

Labour being one of the important components of the construction industry productivity represents a considerable proportion of the final cost usually accounting for between 40 to 60% of building cost (Abdullahi et al., 2010 and Butchan et al., 1993). The assessment of labour rate used for preparation of unit rate for Bill of Quantities requires high level of reliability and accuracy. Essentially, the preparation of Bill of Quantities requires collating cost information on materials, assessing labour and plant outputs and evaluating project overheads. It is important, that cost estimates have clear indications of the level of information reliability and not subsequent explanation of inaccuracy (Morledge, 2006). According to Abdulrazaq et al. (2010) the output constants currently used for preparation of construction estimates are remnants of British colonial heritage or derived from experience of the estimators. Olomolaiye and Ogunlana (1989) reported that firms based their outputs for estimating and planning purposes on experience which at best are educated guesses. Without adequate knowledge of operatives output, it is impossible to draw a reliable construction programmes or make accurate cost estimates for tendering purposes. According to Talhouni (1990), the British Research Establishment (BRE) studies only reported the overall labour variability for house building, but no attempt was made to quantify or explain the performance variability with regard to possible causes or factors that will affect the output of labour on the site and therefore the database used in the previous studies are questionable and are primarily based on activities sampling or data reported by tradesmen However, Yates and Swagata (1993) argued that the productivity of workers is being influenced by factors which vary according to geographical locations. Therefore, if these factors vary acutely with location then how feasible, realistic and accurate are the currently adopted British originated outputs within the Nigerian context? Hence, this research work intends to employ work study approach to empirically establish labour outputs of some selected trades with the view of improving the accuracy of construction cost estimates.

1.2 Statement of the Problem The Nigerian institute of Quantity Surveyors in an attempt to incorporate certain basic features apparent in designs, geographical location and various incursions in construction industry produced the Building and Engineering Standard Method of Measurement (BESMM) to be used for Nigerian construction industry. It is expected that outputs for trade in the Nigerian construction industry conform to work items of the BESMM. The output constants being used for preparation of construction work estimates in Nigeria are not in conformity with the work items in BESMM rather remnants of British colonial heritage or output derived from experience of the estimators are being used. Previous researches carried out on empirical determination of labour output for surface finishes (floor and tiles) did not consider the work items as outlined in the BESMM3

1.3 Aim and Objectives

1.3.1 Aims

The aim of this study is to empirically determine the output for floor screed and tile finishes in the Nigerian construction industry with a view to improving the accuracy of the construction cost estimates.

1.3.2 Objectives

The specific objectives were:

i. To identify factors and operations affecting floor and tile finishes

ii. To analyze the effect of productivity factors on labour output.

iii. To empirically determine the labour outputs of five selected floor and tile finishes work items.

1.4 Justification of the Study

The floor and tile finishes are of various forms, components and thicknesses which influence distinct work items as stated in BESMM and operational in construction site. It also implies that the outputs of the operatives relate to the work items and there are no reliable reference handbooks and manuals of output constants specifically to Nigerian building industry to estimate the required resources and time to control projects. It is also emphasized that an estimator will price work quicker if constant labour rates are used for several months (Brook, 2010). In this research, due to the importance of determining a reliable labour output constants in building industry, labour productivity for floor and tile finishes and factors influencing their reliability in the building construction in Nigeria has to be investigated. The operative output constants can be used by construction estimators and planners for planning, estimating, and controlling the project activities and also be used for management functions (Yates and Swagata, 1993).

1.5 Research Hypotheses

In order to achieve some of the objectives of this research, inferential test was conducted to determine the influence of the labour productivity factors on the labour outputs established. Hence, the following null hypotheses are posited in terms of workers output and productivity factors:

H01: There is no difference in outputs among the various age groups of workers observed on site.

H02: Levels of education does not have impact on outputs of workers observed on site.

H03: The mode of employment has no impact on outputs of workers observed on site.

H04: There is no difference in outputs among years of experience groups of workers observed on site.

H05: There is no significant difference in outputs between changes in period of observation on site.

1.6 Scope and Limitation

i. This research focused on empirical determination of labour output for floor and tile finishes.

ii. The study focused on the following work items; 44mm and 25mm thick floor screed finishes and 600 x 300mm, 400 x 400mm and 300 x 300mm size floor tile finishes as identified in the BESMM.

iii. The study focused on time study aimed at establishing the time for a qualified worker/operative to carry out a task.

1.6. Limitation of the Study

i. The difficulty in assessing whether a worker is operating in full and natural capacity or not during the period of observations might affect the outcome of the findings

ii. The thicknesses of floor screed are not uniformly conformed to the studied thickness which might affect the outcome of the findings

1.7 Basic Assumptions

i. The backgrounds of floor finishes are the same.

ii. The different mixes have no effect on the outcome.

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