As part of an on-going research project on the hybrid precast lattice girder floor system, a series of six specimens were physically tested in the laboratory to investigate the behaviour of the floor at construction stage. The purpose of the experimental tests was to improve the understanding of the floor system at construction stage and examine the key parameters which influence its behaviour at both serviceability and ultimate limit states. The results suggest that there is scope for further optimisation of the lattice girder floor system and that the current design methods may be overly conservative.The lack of comprehensive test data on this floor system limits the development of accurate models which can predict the behaviour of the floor during construction. In this paper, the developments of strain in the various components of the floor system (lattice girder, concrete plank and reinforcement) are measured for a range of lattice girder planks. The use of the transformed area method and Eurocode 3 to predict the behaviour of the plank are investigated in this paper. The analytical model developed is shown to be relatively accurate for predicting the initial stiffness and deflection of planks with tall girders but is not appropriate for planks with low height girders. Areas requiring further research are recommended in this paper to allow formulation of a generic model which would predict the behaviour of the floor system accurately at construction stage.