An installation for treating material having a treatment chamber equipped with an envelope which separates a controlled atmosphere which is present in its interior from an atmosphere which is present outside the envelope and a housing which delimits the treatment chamber. At least one supporting roller for conveying the material is arranged at least partly inside the treatment chamber. One or more mounting apparatuses for mounting at least one supporting roller are arranged outside the housing. A flexible compensating element is provided between at least one mounting apparatus and a wall, which is associated with the latter, of the housing, there being provided a sealing arrangement which is connected to said compensating element and which separates the at least one mounting apparatus from the atmosphere which is present inside the envelope.