A Computational Fluid Dynamics (CFD)-based fire field model utilizing Large Eddy Simulation (LES) approach was applied to a reduced-scale compartment buoyant fire. The complex fire phenomena and fluid motions were simulated utilising coupled subgrid-scale (SGS) turbulence, combustion, radiation and soot models. The detailed chemistry reaction scheme and the multi- tep mechanisms were applied in the strained laminar flamelet model in order to include additional chemical reactions with significant intermediate products. The inclusion of additional reaction steps improved the model replication of the flame structure and the temperature field predictions. An alternative SGS turbulence model other than the classical Smagorinsky-Lilly model, namely the Wall-Adapting Local Eddy-viscosity (WALE) was adopted in this study. It has been shown that the prediction of the ceiling-jet combustion flame was highly dependent on the scalar dissipation rate and turbulent mixing. The modelling of the combustion region was enhanced by the detailed chemistry scheme since it describe the fuel oxidation process more accurately. It was found that the temperature comparison with the experimental data was improved by the detailed chemistry scheme over the multi-step mechanisms.