Forecasting Labour Cost of Construction Trades for Two-Storey Houses: A Single Rate-Based Approach

Abstract

With the labour cost contribution of 30%-50% to the total construction cost of a typical building, construction is recognized as a labour-intensive industry. The extant literature evidenced that there exists labour scarcity in many construction trades, which has caused several negative effects. Hence, the assessment of labour requirements prior to the commencement of the building construction would help to mitigate the effects due to labour shortages at the organization and project level. This research aimed to assess the labour requirements for the cost significant trades of two-storey houses in Sri Lanka. The study involved a survey of thirty-eight (38) two-storey houses to collect the required data. The required data were extracted from the Bill of Quantities (BoQs) of those 38 buildings and assessed based on the norms available in the building schedule of rates (BSRs) practised by the key construction companies. The analysis identified that the finishes, in situ concrete works, doors and windows, services, masonry works, and roof works are the significant trades, respectively in the descending order of their contribution to the total cost. However, in the descending order of their labour requirements, finishing works, masonry works, concrete works, reinforcement, formwork and roofing work are more labour-based activities, require 0.274 skilled labour days and 0.228 unskilled labour days, on average for the construction of per unit (sq.ft) of gross floor area (GFA) of a two-storey house in Sri Lanka. Further, in the case of two-storey houses, cost significant trades contribute to around 19% of its total cost. This would enable estimating the labour cost for a proposed project and thereby implement appropriate strategies to manage the labour shortages in projects and the construction industry as a whole.