Generation of construction wastes constitutes the major impact to the environment. Studies have been directed towards reducing wastes at the various construction processes. However, contractors in Hong Kong are rather conservative and lack motivation in developing new technology for waste minimization. This paper examines the benefits of using prefabrication in reducing material wastage levels for some traditional in-situ trades such as concreting, rebar fixing, bricklaying, drywall, plastering, screeding and tiling in Hong Kong. From the measurement of the thirty construction projects, it is found that waste levels of all major construction trades can be effectively reduced, which is particularly significant in the trade of plastering where 100% saving is achieved after adopting prefabrication. The standardized design of the building can also be useful in the adoption of prefabrication for the private housing projects.