The firebreak problem is studied by adopting a multiphase model based on a continuum formulation of the conservation equations for each of the gas and the N solid phases composing the heterogeneous combustible medium. The strong coupling between the gas and each solid phase is rendered through exchange terms of mass, momentum, and energy. Sub-models for turbulence, soot formation and radiation are incorporated. along with first-order kinetics to describe drying, pyrolysis, and combustion of the organic matter. The model is applied to predict the firebreak efficiency for various conditions of wind and terrain slope. It is found that radiation is responsible for the fire crossing the firebreak. The effects of other parameters investigated and reported include the drag and heat transfer coefficients, the initial fuel volume fraction, and the fuel moisture content.