Vertical thermal stratification will be produced by buoyant plumes in a naturally ventilated enclosure. The buoyant plume located near the wall or corner of a ventilated enclosure will be restricted by the wall or corner during the rising process. Theoretical models are deduced and validated to quantitatively predict the thermal stratification height of an enclosure containing a buoyant plume restricted by a wall or corner. The theoretical models can describe the relationship between the thermal stratification height and the height difference between the top and bottom openings of the enclosure, the effective area of the top and bottom openings of the enclosure and the distance between the plume and the wall or the corner. Thresholds for the distance between the plume and the side boundary are defined to determine whether the plume is restricted by the side boundary. Simultaneous equations containing the enclosure dimensions are proposed to predict the thresholds. These results could be used as a reference on natural ventilation design for buildings containing restricted heat sources to make full use of the effect of thermal plumes and create a suitable indoor environment. (C) 2018 Elsevier B.V. All rights reserved.