A decision support tool for optimising the use of offsite technologies in housebuilding
In recent years the industry has been exhorted to increase its use of offsite technologies, or 'Modem Methods of Construction', in order to address the under-supply and poor build quality of housing. Despite the well-rehearsed benefits of such technologies, the take-up within the industry has been slow. Many studies have attempted to scrutinise the barriers and seek solutions, but the perspectives and practices of housebuilders of using offsite remain unclear. This is significant given that housebuilders contribute nearly 90% to the housing unit completions by the industry overall. This thesis aims to provide a strategy for optimising the use of offsite in housebuilding by investigating UK housebuilders' views on, and utilisations of, such technologies. This has been achieved through a combination of a survey of the top 100 firms, a one and-half-year case study of a large housebuilding organisation, and a series of validation interviews and group exercises, within the existing theoretical framework. The thesis reveals that the current low level of offsite usage in large housebuilders was likely to increase given the pressures to improve quality, time, cost, productivity and health & safety. However, a wider take-up was inhibited by perceived higher capital costs, interfacing problems, long lead-in time, delayed planning process and current manufacturing capacity. For addressing this a framework of strategies is presented, surrounding changing the industry's perceptions, improving procurement, providing better cost data, tackling planning and regulations, encouraging political levers, and providing guidance on decision-making and offsite integration. The thesis then contextualises these findings into the organisational and project contexts, examining the historical and current offsite practices within the general housebuilding business. It reveals that housebuilders primarily aspired to improve business efficiency and mitigate financial risks through the use of offsite despite a complicated agenda for such usage. For using offsite housebuilders developed strategies centred on process, procurement, learning & benchmarking, and training. However, the current heuristic approach to decision-making, coupled with the lack of knowledge of build system selection (BSS) for housebuilding, prevents the benefits from offsite being fully realised. A robust, structured and transparent decision support tool for BSS is developed, transferring knowledge in operational and construction management research to the housebuilding context. It provides an improved decision-making process and databases for system selection. Both the process and data were validated within the wider industry and academic domain, by which the tool was claimed as an effective mechanism for optimising the use of offsite and enhancing organisational learning. The thesis contributes to a better theoretical understanding of offsite and provides strategies for its increased take-up in housebuilding. This helps housebuilding organisations to achieve long-term profitability, but also contributes to addressing the current under-supply of housing. The thesis also contributes to knowledge of decisionmaking and construction management research. This has an implication for wider organisational and decision theory.