Buildings in modern society tend to gradually expand in size due to technological development and overcrowding, which increases the risk of fire. Therefore, continuous efforts are being made to ensure the evacuation safety of occupants by installing firefighting facilities and using flame retardant building finishing materials. This study aims to present a fire performance evaluation plan for building finishing materials using simulations and identify risks that arise from not using flame retardant building finishing materials in medical facilities with vulnerable occupants. A control group for fire performance evaluation was selected using polyurethane foam, while two types of cellulose-based building finishing materials with different flame retardants were chosen for analysis. The cellulose-based finishing materials included expanded graphite, magnesium hydroxide, montmorillonite, and ammonium polyphosphate. Fire performance was evaluated using FDS and path detector simulations based on NES 713 and ISO 5660-1. The results of the study showed that there was a difference of three people in the prediction of the number of deaths depending on the scope of analysis, and it was confirmed that the toxic gas detected was different depending on the added flame retardant. Additionally, construction finishing materials with flame retardant performance increased ASET by at least 130 s compared to polyurethane foam, and the evacuation safety exceeded 1, confirming the effectiveness of securing evacuation stability for occupants.