© 2018 Combustion Institute. All Rights Reserved. Flashover is a major mechanism of fire propagation in compartments. Several models have been proposed to describe this phenomenon using dynamical model approach. The present paper develops a model of this type for a particular case of fire development in a tightly closed compartment. The novelty of the study is in the obtained new approximate analytical solution for the smoke filling problem. This is an essential part of the flashover model. The types of fuels (solid materials) for which the model is particularly suitable are identified. Major outcome of the study is prediction of flashover times as a function of key physical parameters, such as fire heat release rate.