Despite the efforts of governments and firms, the construction industry is trailing other industries in labour productivity. Construction companies are interested in increasing their labour productivity, particularly when demand grows and construction firms cope with labour shortages. Off-site construction has proved to be a favourable policy to increase labour productivity. However, a complete understanding of the factors affecting construction labour productivity is lacking, and it is unclear which factors are influenced by off-site construction. This study developed a conceptual model describing how 15 factors influence the construction process and make a difference in labour productivity between off-site and on-site construction. The conceptual model shows that all 15 factors affect labour productivity in three ways: through direct effects, indirect effects and causal loops. The model is a starting point for further research to determine the impact of off-site construction on labour productivity.

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Refurbishment projects notably for social housing are special kinds of project for many reasons, including inflexible existing stock, low available budgets, involvement of residents staying in their homes during construction. Lean tools could be helpful not only during construction, but also in the preparation of projects including requirements definition, budgeting, design, engineering and planning. The preparation phase also has typical peculiarities including political and social aspects, and is often time and cost consuming. Much lean research has focussed on improving the construction of new built and private sector projects. In contrast this paper aims to demonstrate the merits of lean tooling in the preparation phase of social housing refurbishments. The research reported examined lean tooling applications and their effects on project success in selected case studies of social housing refurbishments in the Netherlands. The research was a design based action research shaping a preselected catalogue of tools i.e. lean toolbox. Next tools were selected together with practitioners, for application in the case projects. After those interventions interviews were held to registers effects on critical success factors in the projects. Most of the tool applications from the lean toolbox approach appeared to be effective in harnessing critical success factors in the projects.@en