Over the past 10 years, there has been a dramatic increase in the costs of building materials in Nigeria, and this development threatens the performance of the construction industry. The objective of the study was to assess the implications of the rising cost of building materials in Lagos State Nigeria. The data pertaining to factors affecting and the implication of rising cost of building materials were sourced from the main contractors, builders' merchants and consultants who are registered with government bodies through questionnaire survey. The data on the prices of building materials were obtained from the archives of the The Nation Newspaper, Lagos QS News Letter, and field survey of builders' merchants in 2012. The averages of the prices were used in the calculations of price indices and rates of inflation on building materials. The three most rated factors responsible for the rising cost of building materials are the exchange rate of the Nigeria Naira with a Mean Rated Average (MRA) = 4.4; cost of fuel and power supply, MRA = 4.3; and changes in government policies and legislation, MRA = 4.2, while fluctuations in the construction cost with MRA = 2.8; reduced volume of construction output, MRA = 2.52; and risk of project abandonment, MRA = 2.51, were the three most rated implications. The study concluded that the implications could result in a downward effect on the gross domestic product (GDP) in the nation's economy.
