High quality modular construction is one of the solutions for the fast growing need for affordable high quality housing in Europe, which can not be solved by conventional building technology. The software environment for automatic modular construction AUTMOD3 has been developed, by University Carlos III de Madrid, in the frame of the European Union project FutureHome. The environment integrated in the Computer Integrated Construction (CIC) concept is composed by several tools: design, planning and simulation, which are linked and able to interchange their data. The tools have been integrated in a well known CAD system and the their work has been tested on an automatic crane for the assembly of pre-fabricated modules on the construction site. This paper describes the AUTMOD3 planning tool.