Hollow bricks are widely used to build facades because of their light weight and high thermal resistance. The air-filled voids within the brick configuration elevates the block’s resistance to heat penetration. Suppressing the natural convection inside the voids increases the blocks thermal resistance. This paper presents a new approach to suppress the convection currents inside brick’s cavities by inserting cell dividers. A numerical study on the effect of inserting a folded sheet inside the cavities of the hollow buildings brick is presented. The folded sheet divides the cavity into several triangles producing a string of small convection cells. The mass, momentum and energy equations are solved for a section of a masonry brick represented by a partitioned squared cavity. The inclined partitions are conductive and are in perfect contact with the walls of the cavity. The two outer vertical sides of the brick section are assumed to be isothermal and the two horizontal sides are insulated. Air, the fluid filling the voids, is modeled as a Newtonian fluid with density defined based on Boussinesq approximation. The heat flux transported across the partitioned voids depends on the number of partitions used and their thermal conductivity. The heat flux through the cavity decreases as the number of partitions increases. Moreover, the convection is nearly diminished when the number partitions becomes six. One day simulation for a typical summer conditions shows that inclined partitions can reduce the heat flux by 37–42% depending on the number of partitions and their material.