The training and learning activities for students are primarily conducted in closed environments. The symptoms resulting from living environments in occupied buildings are referred to as "sick building syndrome (SBS)." The aim of this study is to evaluate the SBS associated with the age of a school building. In this research, grounded research design, which is a type of mixed-method approach, was preferred because qualitative and quantitative methods were used to support each other. Four different schools were selected based on the ages of the school buildings by criterion sampling method. These schools were identified to be 1-, 5-, 10-, and 40-year old buildings. Thus, the research sample comprised a total of 423 students. The students were provided with a questionnaire and the data obtained were analyzed with IBM SPSS 25 software. At the end of the research, it was observed that 329 students experience symptoms in the school, and the most commonly experienced physical symptoms are headache (188 students), physical and mental fatigue (175 students), and concentration disorder (142 students). Moreover, a significant relationship was observed between the symptoms experienced by the students during their time in the school and the symptoms they experienced after school. It was revealed that the most uncomfortable places are corridors and washrooms. In general, it can be concluded that the SBS symptoms are observed in four different buildings, and they vary depending on comfort conditions such as hygiene, ventilation, and heating instead of the age of the school building. Furthermore, it was noted that school principals responsible for the administration of school buildings have an important role in the improving or deteriorating of SBS symptoms.