CHAPTER ONE
INTRODUCTION
Construction industry in Nigeria had been a major source of employment for 70% of labour force in the country, thus it controls the capital flow, as well as labour resources, which has cost implications. Adequate management of these resources is considered an important aspect of   project works; it determines to a large extent   the overall success of project works. So also if the resources are adequately harnessed, issues that pertains to cost overrun would not arise which could result to variations and claims. Some firms rely on claim as a result of variation incurred during the course of the project execution and afterward evaluate their profit after incurring necessary and unnecessary cost on a project. This however has tendency of positioning such in a disadvantageous profit position. An effective cost management strategy is therefore necessary, this could be achieved  through putting in place a proactive cost management strategy. (Love et al, 2005; Ogunsemi and Jagboro, 2005; Ferry et al, 1998).
They described cost management system as a process that should be carried out throughout the life cycle of a project, from the inception to final completion and final payment to the contractor. In the light of this, the timeliness and cost effectiveness of various operation and decision carried out will determine to an extent the magnitude of cost that could be saved on the project. ( Kerzner, 2005; Ogunsemi and Jagboro, 2005).
However Dissanayaka and Kumaraswamy,(1999) opined that Time, Cost, Quality target as well  as project satisfaction tend to be most important key to measure the overall performance of a project work. Furthermore, various research works have also indicated that most project records cost or time overrun during their tenure of execution.( Odusami and Olusanya, 2000).  (Mbachu and Olaoye, 1989; Madewsley, et al, 2004); opined that 51percent of average delay were experienced yearly which culminates in cost overrun, certain factors are responsible for this, to this end however this study attempts at investigating such factors and proffer solution to the pandemic.  The scope of this research work shall be limited to building construction sites within the selected area in Nigeria, Ogun state, Lagos state and Northern part of Nigeria. This is attributable to unique project environment they possess. The aim and objectives of the research are as follows: The research work is to determine the various factors that interplay in impacting project cost performance, investigating the order of severity of the factors, and recommending ways of curtailing the effects. Field survey was carried out with 100 questionnaire distributed  and 67 were used for analysis of response from construction practitioners selected randomly from population of construction firms, The primary data were collected with the aid of structured questionnaire designed on Likert Scale of 1to 4 rating scale.  Mean item score, Simple percentages and severity index were used as analytical tool of the generated data. SPSS (Statistical Packages for Social Science Students) was used in determining pattern of relationship among the cost determinants and variables.