Cost Management Practice of Construction Firms and Its Influencing Factors: Lessons from Southwestern Nigeria Olabosipo, FAGBENLE 1 , Opeyemi, JOSHUA 1 , Adedeji, AFOLABI 1 , Rapheal, OJELABI 1 , Oluseyi, FAGBENLE 2 , Ayoola, FAGBENLE 3 , Maryam, AKOMOLAFE 4 1 Covenant University, Km 10 Idiroko Road, Canaanland, Ota, Ogun State;email:olabosipo.fagbenle@covenantuniversity.edu.ng;ope.joshua@covenantuniversity.edu. ng;adedeji.afolabi@covenantuniversity.edu.ng;rapheal.ojelabi@covenantuniversity.edu.ng 2 DEVTEK Partnership, Plot 15, Lekki_Epe Expressway, Lekki, Lagos, Nigeria 3 Department of General Studies, Osun State College of Technology, Esa-Oke, Nigeria 4 Department of Building Technology, Osun State Polytechnic, Iree, Nigeria ABSTRACT The growing need at maintaining steady cost projection of construction projects has been an issue of serious concern to both the clients and the construction practitioners on sites. Also, cost deviation from initial cost plan and cost budget has been prevalent on construction sites and no concerted efforts have been made at addressing this phenomenon. This study therefore examined the factors that are considered to be affecting the cost management practice of construction firms in the southwestern Nigeria and also proffered possible ways of ameliorating the factors. Using survey approach, one hundred copies each of structured questionnaires were distributed to clients, contractors and consultants on construction sites in the study area while 72, 77 and 78 copies were duly filled and returned by the respondents respectively. Relative Importance Index (RII) technique was used for the analysis. The results revealed that poor leadership and inappropriate management, inefficient deployment of resources, excessive wastage of materials on sites, complex payment mechanisms, theft of materials on sites and variation during construction works are the prevailing factors affecting construction cost management practice in the study area. It was concluded that extra focus should be placed on the identified factors with a view to reducing cost of construction, enhancing construction performance and building confidence within the construction industry in the study area. KEYWORDS: Construction firms; cost management; influencing factors; practice; southwestern Nigeria. INTRODUCTION The growing need for construction of all types coupled with tight monetary supply has provided the construction industry with a big challenge in cost management. Client needs are generally in terms of time, cost and quality and indeed the project success radiates on these terms (Fagbenle & Owolabi, 2012). It is a complex task undertaken by construction firms/project managers in practice which involves constantly measuring progress, evaluating plans and taking corrective Construction Research Congress 2018 692 © ASCE