PurposeConstruction industrialization is emerging in the construction industry, as a result, buildings with prefabricated assemblies are gaining more and more ground. In most situations, the prefabricated building assemblies are installed by labor crews manually. If some assemblies are ill-designed, clashes between labor crews’ workspaces and them may occur, which will have bad effect on workers’ productivity and even incur hazard. The purpose of this paper is to provide a 4D building information modeling (BIM) based approach to find potential workspace conflicts during the installation process of prefabricated building assemblies in the detailed design process so as to eliminate them in advance.Design/methodology/approachFirst, a workspace modeling method is provided; second, three kinds of workspace conflicts are analyzed; third, a 4D-BIM-based approach is established; fourth, a prototype tool based on the approach is developed; and finally, a case study is conducted to test the tool.FindingsThe result shows that the proposed tool can detect or precaution workspace conflicts and visualize them in a series of views; in doing so, valuable information can be obtained for improving the design quality of prefabricated assemblies.Research limitations/implicationsThe proposed approach and tool only concern the congestions caused by ill-designed prefabricated components; the tool needed to be further optimized for speed; the tests on the tool are limited to a single case study; and more tests are needed to verify its effectiveness.Originality/valueThis research provides a 4D-BIM-based approach and a prototype tool for installation workspace analysis. It can be used to provide support for design optimization of prefabricated building assemblies.