Closed-space fires often occur in Hungary, so it is necessary to examine the effects of fires on building structures, taking into account Hungarian architectural features. Fires inside the buildings are characterized by intense heat development and smoke generation that can cause permanent damage to the building structures. Heat and smoke extraction during fire extinguishing is based usually on natural ventilation. Not only being a non-effective process also makes it more difficult to accomplish firefighting tasks. Experiments in this research have been conducted with mobile positive pressure ventilation (PPV) in order to increase the efficiency of the firefighting process and to reduce the adverse effects of fires. The tests have been carried out in unused buildings, providing real conditions. Practical application has been examined in order to reduce the harmful effects of closed-space fires and to provide guidance for professional use. This research based on observations and experiments contributes to enhancing fire safety.